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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Hansen%2C+A&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Hansen%2C+A&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Hansen%2C+A&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.13826">arXiv:2402.13826</a> <span> [<a href="https://arxiv.org/pdf/2402.13826">pdf</a>, <a href="https://arxiv.org/ps/2402.13826">ps</a>, <a href="https://arxiv.org/format/2402.13826">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Linearity of the co-moving velocity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.13826v2-abstract-short" style="display: inline;"> The co-moving velocity is a new variable in the description of immiscible two-phase flow in porous media. It is the saturation-weighted average over the derivatives of the seepage velocities of the two immiscible fluids with respect to saturation. Based on analysis of relative permeability data and computational modeling, it has been proposed that the co-moving velocity is linear when plotted agai… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.13826v2-abstract-full').style.display = 'inline'; document.getElementById('2402.13826v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.13826v2-abstract-full" style="display: none;"> The co-moving velocity is a new variable in the description of immiscible two-phase flow in porous media. It is the saturation-weighted average over the derivatives of the seepage velocities of the two immiscible fluids with respect to saturation. Based on analysis of relative permeability data and computational modeling, it has been proposed that the co-moving velocity is linear when plotted against the derivative of the average seepage velocity with respect to the saturation, the flow derivative. I show here that it is enough to demand that the co-moving velocity is characterized by an additive parameter in addition to the flow derivative to be linear. This has profound consequences for relative permeability theory as it leads to a differential equation relating the two relative permeabilities describing the flow. I present this equation together with two solutions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.13826v2-abstract-full').style.display = 'none'; document.getElementById('2402.13826v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 0 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.16639">arXiv:2312.16639</a> <span> [<a href="https://arxiv.org/pdf/2312.16639">pdf</a>, <a href="https://arxiv.org/format/2312.16639">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Soft Condensed Matter">cond-mat.soft</span> </div> </div> <p class="title is-5 mathjax"> Influence of the imposed flow rate boundary condition on the flow of Bingham fluid in porous media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Talon%2C+L">Laurent Talon</a>, <a href="/search/physics?searchtype=author&query=Hennig%2C+A+A">Andreas Andersen Hennig</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Rosso%2C+A">Alberto Rosso</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.16639v2-abstract-short" style="display: inline;"> The flow of yield stress fluids in porous media presents interesting complexity due to the interplay between the non-linear rheology and the heterogeneity of the medium. A remarkable consequence is that the number of flow paths increases with the applied pressure difference and is responsible for a non-linear Darcy law. Previous studies have focused on the protocol where the pressure difference is… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.16639v2-abstract-full').style.display = 'inline'; document.getElementById('2312.16639v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.16639v2-abstract-full" style="display: none;"> The flow of yield stress fluids in porous media presents interesting complexity due to the interplay between the non-linear rheology and the heterogeneity of the medium. A remarkable consequence is that the number of flow paths increases with the applied pressure difference and is responsible for a non-linear Darcy law. Previous studies have focused on the protocol where the pressure difference is imposed. Here we consider instead the case of imposed flow rate, $Q$. In contrast to Newtonian fluids, the two types of boundary conditions have an important influence on the flow field. Using a two-dimensional pore network model we observe a boundary layer of merging flow paths of size $\ell(Q) \sim Q^{-渭/未}$ where $渭= 0.42 \pm 0.02$ and $未\simeq 0.63 \pm 0.05$. Beyond this layer the density of the flow paths is homogeneous and grows as $Q^渭$. Using a mapping to the directed polymer model we identify $未$ with the roughness exponent of the polymer. We also characterize the statistics of non-flowing surfaces in terms of avalanches pulled at one end. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.16639v2-abstract-full').style.display = 'none'; document.getElementById('2312.16639v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.14799">arXiv:2312.14799</a> <span> [<a href="https://arxiv.org/pdf/2312.14799">pdf</a>, <a href="https://arxiv.org/format/2312.14799">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Disorder-induced non-linear growth of viscously-unstable immiscible two-phase flow fingers in porous media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=M%C3%A9heust%2C+Y">Yves M茅heust</a>, <a href="/search/physics?searchtype=author&query=Fyhn%2C+H">Hursanay Fyhn</a>, <a href="/search/physics?searchtype=author&query=Roy%2C+S">Subhadeep Roy</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.14799v1-abstract-short" style="display: inline;"> The immiscible displacement of a fluid by another one inside a porous medium produces different types of patterns depending on the capillary number Ca and viscosity ratio M. At high Ca, viscous fingers resulting from the viscous instability between fluid-fluid interfaces are believed to exhibit the same Laplacian growth behavior as viscously-unstable fingers observed in Hele-Shaw cells by Saffman… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.14799v1-abstract-full').style.display = 'inline'; document.getElementById('2312.14799v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.14799v1-abstract-full" style="display: none;"> The immiscible displacement of a fluid by another one inside a porous medium produces different types of patterns depending on the capillary number Ca and viscosity ratio M. At high Ca, viscous fingers resulting from the viscous instability between fluid-fluid interfaces are believed to exhibit the same Laplacian growth behavior as viscously-unstable fingers observed in Hele-Shaw cells by Saffman and Taylor [1], or as diffusion limited aggregates (DLA) [2]. I.e., the interface velocity depends linearly on the local gradient of the physical field that drives the growth process (for two-phase flow, the pressure field). However, steady-state two-phase flow in porous media is known to exhibit a regime for which the flow rate depends as a non-linear power law on the global pressure drop, due to the disorder in the capillary barriers at pore throats. A similar nonlinear growth regime was also evidenced experimentally for viscously-unstable drainage in two-dimensional porous media 20 years ago [3]. Here we revisit this flow regime using dynamic pore-network modeling, and explore the non-linearity in the growth properties. We characterize the previously-unstudied dependencies of the statistical finger width and nonlinear growth law's exponent on Ca, and discuss quantitatively, based on theoretical arguments, how disorder in the capillary barriers controls the growth process' non-linearity, and why the flow regime crosses over to Laplacian growth at sufficiently high Ca. In addition, the statistical properties of the fingering patterns are compared to those of Saffman-Taylor fingers, DLA growth patterns, and the results from the aforementioned previous experimental study. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.14799v1-abstract-full').style.display = 'none'; document.getElementById('2312.14799v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">18 pages, 13 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.00362">arXiv:2309.00362</a> <span> [<a href="https://arxiv.org/pdf/2309.00362">pdf</a>, <a href="https://arxiv.org/format/2309.00362">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> The impact of wettability on the co-moving velocity of two-fluid flow in porous media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Alzubaidi%2C+F">Fatimah Alzubaidi</a>, <a href="/search/physics?searchtype=author&query=McClure%2C+J+E">James E. McClure</a>, <a href="/search/physics?searchtype=author&query=Pedersen%2C+H">H氓kon Pedersen</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Berg%2C+C+F">Carl Fredrik Berg</a>, <a href="/search/physics?searchtype=author&query=Mostaghimi%2C+P">Peyman Mostaghimi</a>, <a href="/search/physics?searchtype=author&query=Armstrong%2C+R+T">Ryan T. Armstrong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2309.00362v1-abstract-short" style="display: inline;"> The impact of wettability on the co-moving velocity of two-fluid flow in porous media is analyzed herein. The co-moving velocity, developed by Roy et al. (2022), is a novel representation of the flow behavior of two fluids through porous media. Our study aims to better understand the behavior of the co-moving velocity by analyzing simulation data under various wetting conditions. The simulations w… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.00362v1-abstract-full').style.display = 'inline'; document.getElementById('2309.00362v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.00362v1-abstract-full" style="display: none;"> The impact of wettability on the co-moving velocity of two-fluid flow in porous media is analyzed herein. The co-moving velocity, developed by Roy et al. (2022), is a novel representation of the flow behavior of two fluids through porous media. Our study aims to better understand the behavior of the co-moving velocity by analyzing simulation data under various wetting conditions. The simulations were conducted using the Lattice-Boltzmann color-fluid model and evaluated the relative permeability for different wetting conditions on the same rock. The analysis of the simulation data followed the methodology proposed by Roy et al. (2022) to reconstruct a constitutive equation for the co-moving velocity. Surprisingly, it was found that the coefficients of the constitutive equation were nearly the same for all wetting conditions. Based on these results, a simple approach was proposed to reconstruct the oil phase relative permeability using only the co-moving velocity relationship and water phase relative permeability. This proposed method provides new insights into the dependency of relative permeability curves, which has implications for the history matching of production data and solving the associated inverse problem. The research findings contribute to a better understanding of the impact of wettability on fluid flow in porous media and provide a practical approach for estimating relative permeability based on the co-moving velocity relationship, which has never been shown before. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.00362v1-abstract-full').style.display = 'none'; document.getElementById('2309.00362v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.13451">arXiv:2307.13451</a> <span> [<a href="https://arxiv.org/pdf/2307.13451">pdf</a>, <a href="https://arxiv.org/format/2307.13451">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Soft Condensed Matter">cond-mat.soft</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Transition from viscous fingers to foam during drainage in heterogeneous porous media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Lanza%2C+F">Federico Lanza</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Rosso%2C+A">Alberto Rosso</a>, <a href="/search/physics?searchtype=author&query=Talon%2C+L">Laurent Talon</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2307.13451v1-abstract-short" style="display: inline;"> We investigate the behavior of drainage displacements in heterogeneous porous media finding a transition from viscous fingering to foam-like region. A pore network model incorporating the formation of blobs is adopted to study this phenomenon. By imposing a pressure difference between the inlet and outlet, we observe that the displacement pattern undergoes a significant transition from a continuou… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.13451v1-abstract-full').style.display = 'inline'; document.getElementById('2307.13451v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.13451v1-abstract-full" style="display: none;"> We investigate the behavior of drainage displacements in heterogeneous porous media finding a transition from viscous fingering to foam-like region. A pore network model incorporating the formation of blobs is adopted to study this phenomenon. By imposing a pressure difference between the inlet and outlet, we observe that the displacement pattern undergoes a significant transition from a continuous front of growing viscous fingers to the emergence of foam, which develops and propagates until breakthrough. This transition occurs at a specific distance from the inlet, which we measure and analyze as a function of the viscosity ratio and the capillary number, demonstrating that it follows a non-trivial power-law decay with both the parameters. Moreover, we discuss the relationship between the evolution of the total flow rate and the local pressure drop, showing that the foam developed reduces global mobility. We observe that foam is formed from the fragmentation of viscous fingers beneath the front, and this instability mechanism is connected with fluctuations of the local flow rate, which we analyze both in the viscous fingering region and in the foam region. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.13451v1-abstract-full').style.display = 'none'; document.getElementById('2307.13451v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Main text: 14 pages, 11 Figures. Supplementary Material: 3 pages, 5 Figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.14079">arXiv:2302.14079</a> <span> [<a href="https://arxiv.org/pdf/2302.14079">pdf</a>, <a href="https://arxiv.org/format/2302.14079">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Soft Condensed Matter">cond-mat.soft</span> </div> </div> <p class="title is-5 mathjax"> Effective rheology of immiscible two-phase flow in porous media consisting of random mixtures of grains having two types of wetting properties </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Fyhn%2C+H">Hursanay Fyhn</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2302.14079v2-abstract-short" style="display: inline;"> We consider the effective rheology of immiscible two-phase flow in porous media with random mixtures of two types of grains with different wetting properties using a dynamic pore network model under steady-state. Two immiscible fluids A and B flow through the pores between these two types of grains denoted "+" and "-". Fluid A is fully wetting and B is fully non-wetting with respect to "+" grains… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.14079v2-abstract-full').style.display = 'inline'; document.getElementById('2302.14079v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.14079v2-abstract-full" style="display: none;"> We consider the effective rheology of immiscible two-phase flow in porous media with random mixtures of two types of grains with different wetting properties using a dynamic pore network model under steady-state. Two immiscible fluids A and B flow through the pores between these two types of grains denoted "+" and "-". Fluid A is fully wetting and B is fully non-wetting with respect to "+" grains and opposite with "-" grains. The direction of the capillary forces in the links between two "+" grains is therefore opposite compared to that between two "-" grains, whereas the capillary forces in the links between two opposite types of grains average to zero. For a window of grain occupation probabilities, a percolating regime appears where there is a high probability of having connected paths with zero capillary forces. Due to these paths, no minimum threshold pressure is required to start a flow in this regime. While varying the pressure drop across the porous medium from low to high in this regime, the relation between the volumetric flow rate and the pressure drop goes from being linear to a power law with exponent 2.56 to linear again. Outside the percolation regime, there is a threshold pressure. No linear regime is observed for low pressure drops. When the pressure drop is high enough for there to be flow, we find that the flow rate depends on the excess pressure drop to an exponents around 2.2-2.3. At even higher pressure drops, the relation is linear. We see no change in exponent for the intermediate regime at the percolation critical points where the zero-capillary force paths disappear. We measure the mobility at the percolation threshold at low pressure drops so that the flow rate versus pressure drop is linear. Assuming a power law, the mobility is proportional to the difference between the occupation probability and the critical occupation probability to a power of around 5.7. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.14079v2-abstract-full').style.display = 'none'; document.getElementById('2302.14079v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.07285">arXiv:2212.07285</a> <span> [<a href="https://arxiv.org/pdf/2212.07285">pdf</a>, <a href="https://arxiv.org/ps/2212.07285">ps</a>, <a href="https://arxiv.org/format/2212.07285">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Parameterizations of Immiscible Two-Phase Flow in Porous Media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Pedersen%2C+H">H氓kon Pedersen</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.07285v1-abstract-short" style="display: inline;"> A fundamental variable characterizing immiscible two-phase flow in porous media is the wetting saturation, which is the ratio between the pore volume filled with wetting fluid and the total pore volume. More generally, this variable comes from a specific choice of coordinates on some underlying space, the domain of variables that can be used to express the volumetric flow rate. The underlying math… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.07285v1-abstract-full').style.display = 'inline'; document.getElementById('2212.07285v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.07285v1-abstract-full" style="display: none;"> A fundamental variable characterizing immiscible two-phase flow in porous media is the wetting saturation, which is the ratio between the pore volume filled with wetting fluid and the total pore volume. More generally, this variable comes from a specific choice of coordinates on some underlying space, the domain of variables that can be used to express the volumetric flow rate. The underlying mathematical structure allows for the introduction of other variables containing the same information, but which are more convenient from a theoretical point of view. We introduce along these lines polar coordinates on this underlying space, where the angle plays a role similar to the wetting saturation. We derive relations between these new variables based on the Euler homogeneity theorem. We formulate these relations in a coordinate-free fashion using differential forms. Lastly, we discuss and interpret the co-moving velocity in terms of this coordinate-free representation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.07285v1-abstract-full').style.display = 'none'; document.getElementById('2212.07285v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.00030">arXiv:2209.00030</a> <span> [<a href="https://arxiv.org/pdf/2209.00030">pdf</a>, <a href="https://arxiv.org/format/2209.00030">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.physa.2023.128626">10.1016/j.physa.2023.128626 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Local Statistics of Immiscible and Incompressible Two-Phase Flow in Porous Media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Fyhn%2C+H">Hursanay Fyhn</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.00030v2-abstract-short" style="display: inline;"> We consider immiscible and incompressible two-phase flow in porous media under steady-state conditions using a dynamic pore network model. We focus on the fluctuations in a Representative Elementary Area (REA), with the aim to demonstrate that the statistical distributions of the volumetric flow rate and the saturation within the REA become independent of the size of the entire model when the mode… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.00030v2-abstract-full').style.display = 'inline'; document.getElementById('2209.00030v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.00030v2-abstract-full" style="display: none;"> We consider immiscible and incompressible two-phase flow in porous media under steady-state conditions using a dynamic pore network model. We focus on the fluctuations in a Representative Elementary Area (REA), with the aim to demonstrate that the statistical distributions of the volumetric flow rate and the saturation within the REA become independent of the size of the entire model when the model is large enough. This independence is a necessary condition for developing a local statistical theory for the flow, which in turn opens for the possibility to formulate a description at scales large enough for the typical pore size to be negligible using differential equations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.00030v2-abstract-full').style.display = 'none'; document.getElementById('2209.00030v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.10503">arXiv:2207.10503</a> <span> [<a href="https://arxiv.org/pdf/2207.10503">pdf</a>, <a href="https://arxiv.org/format/2207.10503">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Steady-state two-phase flow of compressible and incompressible fluids in a capillary tube of varying radius </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Cheon%2C+H+L">Hyejeong L. Cheon</a>, <a href="/search/physics?searchtype=author&query=Fyhn%2C+H">Hursanay Fyhn</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Wilhelmsen%2C+%C3%98">脴ivind Wilhelmsen</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2207.10503v1-abstract-short" style="display: inline;"> We study immiscible two-phase flow of a compressible and an incompressible fluid inside a capillary tube of varying radius under steady-state conditions. The incompressible fluid is Newtonian and the compressible fluid is an inviscid ideal gas. The surface tension associated with the interfaces between the two fluids introduces capillary forces that vary along the tube due to the variation in the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.10503v1-abstract-full').style.display = 'inline'; document.getElementById('2207.10503v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.10503v1-abstract-full" style="display: none;"> We study immiscible two-phase flow of a compressible and an incompressible fluid inside a capillary tube of varying radius under steady-state conditions. The incompressible fluid is Newtonian and the compressible fluid is an inviscid ideal gas. The surface tension associated with the interfaces between the two fluids introduces capillary forces that vary along the tube due to the variation in the tube radius. The interplay between effects due to the capillary forces and the compressibility results in a set of properties that are different from incompressible two-phase flow. As the fluids move towards the outlet, the bubbles of the compressible fluid grow in volume due to the decrease in pressure. The volumetric growth of the compressible bubbles makes the volumetric flow rate at the outlet higher than at the inlet. The growth is not only a function of the pressure drop across the tube, but also of the ambient pressure. Furthermore, the capillary forces create an effective threshold below which there is no flow. Above the threshold, the system shows a weak non-linearity between the flow rates and the effective pressure drop, where the non-linearity also depends on the absolute pressures across the tube. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.10503v1-abstract-full').style.display = 'none'; document.getElementById('2207.10503v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2205.13791">arXiv:2205.13791</a> <span> [<a href="https://arxiv.org/pdf/2205.13791">pdf</a>, <a href="https://arxiv.org/format/2205.13791">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.advwatres.2022.104336">10.1016/j.advwatres.2022.104336 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A statistical mechanics for immiscible and incompressible two-phase flow in porous media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Flekk%C3%B8y%2C+E+G">Eirik G. Flekk酶y</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Slotte%2C+P+A">Per Arne Slotte</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2205.13791v1-abstract-short" style="display: inline;"> We construct a statistical mechanics for immiscible and incompressible two-phase flow in porous media under local steady-state conditions based on the Jaynes maximum entropy principle. A cluster entropy is assigned to our lack of knowledge of, and control over, the fluid and flow configurations in the pore space. As a consequence, two new variables describing the flow emerge: The agiture, that des… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.13791v1-abstract-full').style.display = 'inline'; document.getElementById('2205.13791v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2205.13791v1-abstract-full" style="display: none;"> We construct a statistical mechanics for immiscible and incompressible two-phase flow in porous media under local steady-state conditions based on the Jaynes maximum entropy principle. A cluster entropy is assigned to our lack of knowledge of, and control over, the fluid and flow configurations in the pore space. As a consequence, two new variables describing the flow emerge: The agiture, that describes the level of agitation of the two fluids, and the flow derivative which is conjugate to the saturation. Agiture and flow derivative are the analogs of temperature and chemical potential in standard (thermal) statistical mechanics. The associated thermodynamics-like formalism reveals a number of hitherto unknown relations between the variables that describe the flow, including fluctuations. The formalism opens for new approaches to characterize porous media with respect to multi-phase flow for practical applications, replacing the simplistic relative permeability theory while still keeping the number of variables tractable. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.13791v1-abstract-full').style.display = 'none'; document.getElementById('2205.13791v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 May, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.09206">arXiv:2110.09206</a> <span> [<a href="https://arxiv.org/pdf/2110.09206">pdf</a>, <a href="https://arxiv.org/format/2110.09206">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Soft Condensed Matter">cond-mat.soft</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> </div> <p class="title is-5 mathjax"> Burst dynamics, up-scaling and dissipation of slow drainage in porous media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=M%C3%A5l%C3%B8y%2C+K+J">Knut J酶rgen M氓l酶y</a>, <a href="/search/physics?searchtype=author&query=Moura%2C+M">Marcel Moura</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Flekk%C3%B8y%2C+E+G">Eirik Grude Flekk酶y</a>, <a href="/search/physics?searchtype=author&query=Toussaint%2C+R">Renaud Toussaint</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2110.09206v3-abstract-short" style="display: inline;"> We present a theoretical and experimental investigation of drainage in porous media. The study is limited to stabilized fluid fronts at moderate injection rates, but it takes into account capillary, viscous, and gravitational forces. In this theory the work applied on the system, the energy dissipation, the final saturation and the width of the stabilized fluid front can all be calculated if we kn… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.09206v3-abstract-full').style.display = 'inline'; document.getElementById('2110.09206v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.09206v3-abstract-full" style="display: none;"> We present a theoretical and experimental investigation of drainage in porous media. The study is limited to stabilized fluid fronts at moderate injection rates, but it takes into account capillary, viscous, and gravitational forces. In this theory the work applied on the system, the energy dissipation, the final saturation and the width of the stabilized fluid front can all be calculated if we know the dimensionless fluctuation number, the wetting properties, the surface tension between the fluids, the fractal dimensions of the invasion front and the invading structure, and the exponent describing the divergence of the correlation length in percolation. This theoretical description explains how the Haines jumps' local activity and dissipation relate to dissipation on larger scales. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.09206v3-abstract-full').style.display = 'none'; document.getElementById('2110.09206v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 11 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.10187">arXiv:2108.10187</a> <span> [<a href="https://arxiv.org/pdf/2108.10187">pdf</a>, <a href="https://arxiv.org/ps/2108.10187">ps</a>, <a href="https://arxiv.org/format/2108.10187">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> The Co-Moving Velocity in Immiscible Two-Phase Flow in Porous Media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Roy%2C+S">Subhadeep Roy</a>, <a href="/search/physics?searchtype=author&query=Pedersen%2C+H">H氓kon Pedersen</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.10187v2-abstract-short" style="display: inline;"> We present a continuum (i.e., an effective) description of immiscible two-phase flow in porous media characterized by two fields, the pressure and the saturation. Gradients in these two fields are the driving forces that move the immiscible fluids around. The fluids are characterized by two seepage velocity fields, one for each fluid. Following Hansen et al.\ (Transport in Porous Media, 125, 565 (… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.10187v2-abstract-full').style.display = 'inline'; document.getElementById('2108.10187v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.10187v2-abstract-full" style="display: none;"> We present a continuum (i.e., an effective) description of immiscible two-phase flow in porous media characterized by two fields, the pressure and the saturation. Gradients in these two fields are the driving forces that move the immiscible fluids around. The fluids are characterized by two seepage velocity fields, one for each fluid. Following Hansen et al.\ (Transport in Porous Media, 125, 565 (2018)), we construct a two-way transformation between the velocity couple consisting of the seepage velocity of each fluid, to a velocity couple consisting of the average seepage velocity of both fluids and a new velocity parameter, the co-moving velocity. The co-moving velocity is related but not equal to velocity difference between the two immiscible fluids. The two-way mapping, the mass conservation equation and the constitutive equations for the average seepage velocity and the co-moving velocity form a closed set of equations that determine the flow. There is growing experimental, computational and theoretical evidence that constitutive equation for the average seepage velocity has the form of a power law in the pressure gradient over a wide range of capillary numbers. Through the transformation between the two velocity couples, this constitutive equation may be taken directly into account in the equations describing the flow of each fluid. This is e.g., not possible using relative permeability theory. By reverse engineering relative permeability data from the literature, we construct the constitutive equation for the co-moving velocity. We also calculate the co-moving constitutive equation using a dynamic pore network model over a wide range of parameters, from where the flow is viscosity dominated to where the capillary and viscous forces compete. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.10187v2-abstract-full').style.display = 'none'; document.getElementById('2108.10187v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">29 pages, 18 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.04325">arXiv:2106.04325</a> <span> [<a href="https://arxiv.org/pdf/2106.04325">pdf</a>, <a href="https://arxiv.org/format/2106.04325">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> </div> </div> <p class="title is-5 mathjax"> Non-Newtonian rheology in a capillary tube with varying radius </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Lanza%2C+F">Federico Lanza</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Rosso%2C+A">Alberto Rosso</a>, <a href="/search/physics?searchtype=author&query=Talon%2C+L">Laurent Talon</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2106.04325v1-abstract-short" style="display: inline;"> The flow through a capillary tube with non-constant radius and where bubbles of yield stress fluid are injected is strongly non-linear. In particular below a finite yield pressure drop, $P_y$, flow is absent, while a singular behaviour is expected above it. In this paper we compute the yield pressure drop statistics and the mean flow rate in two cases: (i) when a single bubble is injected, (ii) wh… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.04325v1-abstract-full').style.display = 'inline'; document.getElementById('2106.04325v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.04325v1-abstract-full" style="display: none;"> The flow through a capillary tube with non-constant radius and where bubbles of yield stress fluid are injected is strongly non-linear. In particular below a finite yield pressure drop, $P_y$, flow is absent, while a singular behaviour is expected above it. In this paper we compute the yield pressure drop statistics and the mean flow rate in two cases: (i) when a single bubble is injected, (ii) when many bubbles are randomly injected in the fluid. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.04325v1-abstract-full').style.display = 'none'; document.getElementById('2106.04325v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 8 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.07486">arXiv:2105.07486</a> <span> [<a href="https://arxiv.org/pdf/2105.07486">pdf</a>, <a href="https://arxiv.org/format/2105.07486">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/s11242-021-01674-3">10.1007/s11242-021-01674-3 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Rheology of immiscible two-phase flow in mixed wet porous media: Dynamic pore network model and capillary fiber bundle model results </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Fyhn%2C+H">Hursanay Fyhn</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Roy%2C+S">Subhadeep Roy</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2105.07486v2-abstract-short" style="display: inline;"> Immiscible two-phase flow in porous media with mixed wet conditions was examined using a capillary fiber bundle model, which is analytically solvable, and a dynamic pore network model. The mixed wettability was implemented in the models by allowing each tube or link to have a different wetting angle chosen randomly from a given distribution. Both models showed that mixed wettability can have signi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.07486v2-abstract-full').style.display = 'inline'; document.getElementById('2105.07486v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.07486v2-abstract-full" style="display: none;"> Immiscible two-phase flow in porous media with mixed wet conditions was examined using a capillary fiber bundle model, which is analytically solvable, and a dynamic pore network model. The mixed wettability was implemented in the models by allowing each tube or link to have a different wetting angle chosen randomly from a given distribution. Both models showed that mixed wettability can have significant influence on the rheology in terms of the dependence of the global volumetric flow rate on the global pressure drop. In the capillary fiber bundle model, for small pressure drops when only a small fraction of the tubes were open, it was found that the volumetric flow rate depended on the excess pressure drop as a power law with an exponent equal to 3/2 or 2 depending on the minimum pressure drop necessary for flow. When all the tubes were open due to a high pressure drop, the volumetric flow rate depended linearly on the pressure drop, independent of the wettability. In the transition region in between where most of the tubes opened, the volumetric flow depended more sensitively on the wetting angle distribution function and was in general not a simple power law. The dynamic pore network model results also showed a linear dependence of the flow rate on the pressure drop when the pressure drop is large. However, out of this limit the dynamic pore network model demonstrated a more complicated behaviour that depended on the mixed wettability condition and the saturation. In particular, the exponent relating volumetric flow rate to the excess pressure drop could take on values anywhere between 1.0 and 1.8. The values of the exponent were highest for saturations approaching 0.5, also, the exponent generally increased when the difference in wettability of the two fluids were larger and when this difference was present for a larger fraction of the porous network. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.07486v2-abstract-full').style.display = 'none'; document.getElementById('2105.07486v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.06847">arXiv:2105.06847</a> <span> [<a href="https://arxiv.org/pdf/2105.06847">pdf</a>, <a href="https://arxiv.org/format/2105.06847">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Role of pore-size distribution on effective rheology of two-phase flow in porous media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Roy%2C+S">Subhadeep Roy</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2105.06847v1-abstract-short" style="display: inline;"> The flow of immiscible fluids inside a porous medium shows non-linearity in the form of a power law in the rheological properties of the fluids under steady state flow conditions. However, different experimental and numerical studies have reported different values for the exponent related to this power law. Here we explore how the rheological properties of the two-phase flow in porous media depend… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.06847v1-abstract-full').style.display = 'inline'; document.getElementById('2105.06847v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.06847v1-abstract-full" style="display: none;"> The flow of immiscible fluids inside a porous medium shows non-linearity in the form of a power law in the rheological properties of the fluids under steady state flow conditions. However, different experimental and numerical studies have reported different values for the exponent related to this power law. Here we explore how the rheological properties of the two-phase flow in porous media depends on the distribution of the pore sizes and how it affects the power-law exponent. The pore-size distribution controls fluctuation in the pore radii and their density in a porous material. We present two approaches, analytical calculations using a capillary bundle model and numerical simulations using dynamic pore-network modeling. We observe crossover from a non-linear to linear rheology when increasing the flow rate where the non-linear part is highly affected by the pore-size distribution. We have also carried out the study for different saturations of the two fluids. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.06847v1-abstract-full').style.display = 'none'; document.getElementById('2105.06847v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.07725">arXiv:2104.07725</a> <span> [<a href="https://arxiv.org/pdf/2104.07725">pdf</a>, <a href="https://arxiv.org/ps/2104.07725">ps</a>, <a href="https://arxiv.org/format/2104.07725">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/5.0054008">10.1063/5.0054008 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Cross-beam energy transfer saturation by ion trapping-induced detuning </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Nguyen%2C+K+L">K. L. Nguyen</a>, <a href="/search/physics?searchtype=author&query=Yin%2C+L">L. Yin</a>, <a href="/search/physics?searchtype=author&query=Albright%2C+B+J">B. J. Albright</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A+M">A. M. Hansen</a>, <a href="/search/physics?searchtype=author&query=Froula%2C+D+H">D. H. Froula</a>, <a href="/search/physics?searchtype=author&query=Turnbull%2C+D">D. Turnbull</a>, <a href="/search/physics?searchtype=author&query=Follett%2C+R+K">R. K. Follett</a>, <a href="/search/physics?searchtype=author&query=Palastro%2C+J+P">J. P. Palastro</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2104.07725v1-abstract-short" style="display: inline;"> The performance of direct-drive inertial confinement fusion implosions relies critically on the coupling of laser energy to the target plasma. Cross-beam energy transfer (CBET), the resonant exchange of energy between intersecting laser beams mediated by ponderomotively driven ion-acoustic waves (IAW), inhibits this coupling by scattering light into unwanted directions. The variety of beam interse… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.07725v1-abstract-full').style.display = 'inline'; document.getElementById('2104.07725v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.07725v1-abstract-full" style="display: none;"> The performance of direct-drive inertial confinement fusion implosions relies critically on the coupling of laser energy to the target plasma. Cross-beam energy transfer (CBET), the resonant exchange of energy between intersecting laser beams mediated by ponderomotively driven ion-acoustic waves (IAW), inhibits this coupling by scattering light into unwanted directions. The variety of beam intersection angles and varying plasma conditions in an implosion results in IAWs with a range of phase velocities. Here we show that CBET saturates through a resonance detuning that depends on the IAW phase velocity and that results from trapping-induced modifications to the ion distribution functions. For smaller phase velocities, the modifications to the distribution functions can rapidly thermalize in the presence of mid-Z ions, leading to a blueshift in the resonant frequency. For larger phase velocities, the modifications can persist, leading to a redshift in the resonant frequency. Ultimately, these results may reveal pathways towards CBET mitigation and inform reduced models for radiation hydrodynamics codes to improve their predictive capability. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.07725v1-abstract-full').style.display = 'none'; document.getElementById('2104.07725v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.00831">arXiv:2008.00831</a> <span> [<a href="https://arxiv.org/pdf/2008.00831">pdf</a>, <a href="https://arxiv.org/format/2008.00831">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> </div> <p class="title is-5 mathjax"> Enhanced observation time of magneto-optical traps using micro-machined non-evaporable getter pumps </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Boudot%2C+R">Rodolphe Boudot</a>, <a href="/search/physics?searchtype=author&query=McGilligan%2C+J+P">James P. McGilligan</a>, <a href="/search/physics?searchtype=author&query=Moore%2C+K+R">Kaitlin R. Moore</a>, <a href="/search/physics?searchtype=author&query=Maurice%2C+V">Vincent Maurice</a>, <a href="/search/physics?searchtype=author&query=Martinez%2C+G+D">Gabriela D. Martinez</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Azure Hansen</a>, <a href="/search/physics?searchtype=author&query=de+Clercq%2C+E">Emeric de Clercq</a>, <a href="/search/physics?searchtype=author&query=Kitching%2C+J">John Kitching</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2008.00831v1-abstract-short" style="display: inline;"> We show that micro-machined non-evaporable getter pumps (NEGs) can extend the time over which laser cooled atoms canbe produced in a magneto-optical trap (MOT), in the absence of other vacuum pumping mechanisms. In a first study, weincorporate a silicon-glass microfabricated ultra-high vacuum (UHV) cell with silicon etched NEG cavities and alumino-silicateglass (ASG) windows and demonstrate the ob… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.00831v1-abstract-full').style.display = 'inline'; document.getElementById('2008.00831v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.00831v1-abstract-full" style="display: none;"> We show that micro-machined non-evaporable getter pumps (NEGs) can extend the time over which laser cooled atoms canbe produced in a magneto-optical trap (MOT), in the absence of other vacuum pumping mechanisms. In a first study, weincorporate a silicon-glass microfabricated ultra-high vacuum (UHV) cell with silicon etched NEG cavities and alumino-silicateglass (ASG) windows and demonstrate the observation of a repeatedly-loading MOT over a 10 minute period with a single laser-activated NEG. In a second study, the capacity of passive pumping with laser activated NEG materials is further investigated ina borosilicate glass-blown cuvette cell containing five NEG tablets. In this cell, the MOT remained visible for over 4 days withoutany external active pumping system. This MOT observation time exceeds the one obtained in the no-NEG scenario by almostfive orders of magnitude. The cell scalability and potential vacuum longevity made possible with NEG materials may enable inthe future the development of miniaturized cold-atom instruments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.00831v1-abstract-full').style.display = 'none'; document.getElementById('2008.00831v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2005.11929">arXiv:2005.11929</a> <span> [<a href="https://arxiv.org/pdf/2005.11929">pdf</a>, <a href="https://arxiv.org/ps/2005.11929">ps</a>, <a href="https://arxiv.org/format/2005.11929">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1364/OE.399988">10.1364/OE.399988 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Robust inertial sensing with point-source atom interferometry for interferograms spanning a partial period </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Chen%2C+Y">Yun-Jhih Chen</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Azure Hansen</a>, <a href="/search/physics?searchtype=author&query=Shuker%2C+M">Moshe Shuker</a>, <a href="/search/physics?searchtype=author&query=Boudot%2C+R">Rodolphe Boudot</a>, <a href="/search/physics?searchtype=author&query=Kitching%2C+J">John Kitching</a>, <a href="/search/physics?searchtype=author&query=Donley%2C+E+A">Elizabeth A. Donley</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2005.11929v2-abstract-short" style="display: inline;"> Point source atom interferometry (PSI) uses the velocity distribution in a cold atom cloud to simultaneously measure one axis of acceleration and two axes of rotation from the phase, orientation, and period of atomic interference fringe images. For practical applications in inertial sensing and precision measurement, it is important to be able to measure a wide range of system rotation rates, corr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.11929v2-abstract-full').style.display = 'inline'; document.getElementById('2005.11929v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2005.11929v2-abstract-full" style="display: none;"> Point source atom interferometry (PSI) uses the velocity distribution in a cold atom cloud to simultaneously measure one axis of acceleration and two axes of rotation from the phase, orientation, and period of atomic interference fringe images. For practical applications in inertial sensing and precision measurement, it is important to be able to measure a wide range of system rotation rates, corresponding to interferograms with far less than one full interference fringe to very many fringes. The interferogram analysis techniques used previously for PSI are not sensitive to low rotation rates, which generates less one full interference fringe across the cloud, limiting the dynamic range of the instrument. We introduce an experimental method, new to atom interferometry and closely related to optical phase-shifting interferometry, that is effective in extracting rotation values from signals consisting of fractional fringes as well as many fringes without prior knowledge of the rotation rate. Our method uses four interferograms, each with a controlled Raman laser phase shift, to reconstruct the underlying atomic interferometer phase map. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.11929v2-abstract-full').style.display = 'none'; document.getElementById('2005.11929v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 June, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 May, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2001.04332">arXiv:2001.04332</a> <span> [<a href="https://arxiv.org/pdf/2001.04332">pdf</a>, <a href="https://arxiv.org/format/2001.04332">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Onsager-Symmetry Obeyed in Athermal Mesoscopic Systems: Two-Phase Flow in Porous Media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Winkler%2C+M">Mathias Winkler</a>, <a href="/search/physics?searchtype=author&query=Gjennestad%2C+M+A">Magnus Aa. Gjennestad</a>, <a href="/search/physics?searchtype=author&query=Bedeaux%2C+D">Dick Bedeaux</a>, <a href="/search/physics?searchtype=author&query=Kjelstrup%2C+S">Signe Kjelstrup</a>, <a href="/search/physics?searchtype=author&query=Cabriolu%2C+R">Raffaela Cabriolu</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2001.04332v1-abstract-short" style="display: inline;"> We compute the fluid flow time-correlation functions of incompressible, immiscible two-phase flow in porous media using a 2D network model. Given a properly chosen representative elementary volume, the flow rate distributions are Gaussian and the integrals of time correlation functions of the flows are found to converge to a finite value. The integrated cross-correlations become symmetric, obeying… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.04332v1-abstract-full').style.display = 'inline'; document.getElementById('2001.04332v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2001.04332v1-abstract-full" style="display: none;"> We compute the fluid flow time-correlation functions of incompressible, immiscible two-phase flow in porous media using a 2D network model. Given a properly chosen representative elementary volume, the flow rate distributions are Gaussian and the integrals of time correlation functions of the flows are found to converge to a finite value. The integrated cross-correlations become symmetric, obeying Onsager's reciprocal relations. These findings support the proposal of a non-equilibrium thermodynamic description for two-phase flow in porous media. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.04332v1-abstract-full').style.display = 'none'; document.getElementById('2001.04332v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.05248">arXiv:1912.05248</a> <span> [<a href="https://arxiv.org/pdf/1912.05248">pdf</a>, <a href="https://arxiv.org/format/1912.05248">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Immiscible two-phase flow in porous media: Effective rheology in the continuum limit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Roy%2C+S">Subhadeep Roy</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.05248v2-abstract-short" style="display: inline;"> It is becoming increasingly clear that there is a regime in immiscible two-phase flow in porous media where the flow rate depends of the pressure drop as a power law with exponent different than one. This occurs when the capillary forces and viscous forces both influence the flow. At higher flow rates, where the viscous forces dominate, the flow rate depends linearly on the pressure drop. The ques… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.05248v2-abstract-full').style.display = 'inline'; document.getElementById('1912.05248v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.05248v2-abstract-full" style="display: none;"> It is becoming increasingly clear that there is a regime in immiscible two-phase flow in porous media where the flow rate depends of the pressure drop as a power law with exponent different than one. This occurs when the capillary forces and viscous forces both influence the flow. At higher flow rates, where the viscous forces dominate, the flow rate depends linearly on the pressure drop. The question we pose here is what happens to the linear regime when the system size is increased. Based on analytical calculations using the capillary fiber bundle model and on numerical simulations using a dynamical network model, we find that the non-linear regime moves towards smaller and smaller pressure gradients as the system size grows. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.05248v2-abstract-full').style.display = 'none'; document.getElementById('1912.05248v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.03248">arXiv:1912.03248</a> <span> [<a href="https://arxiv.org/pdf/1912.03248">pdf</a>, <a href="https://arxiv.org/ps/1912.03248">ps</a>, <a href="https://arxiv.org/format/1912.03248">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="History and Philosophy of Physics">physics.hist-ph</span> </div> </div> <p class="title is-5 mathjax"> Wigner's Isolated Friend </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Arne Hansen</a>, <a href="/search/physics?searchtype=author&query=Wolf%2C+S">Stefan Wolf</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.03248v1-abstract-short" style="display: inline;"> The measurement problem is seen as an ambiguity of quantum mechanics, or, beyond that, as a contradiction within the theory: Quantum mechanics offers two conflicting descriptions of the Wigner's-friend experiment. As we argue in this note there are, however, obstacles from within quantum mechanics and regarding our perspective onto doing physics towards fully describing a measurement. We conclude… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03248v1-abstract-full').style.display = 'inline'; document.getElementById('1912.03248v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.03248v1-abstract-full" style="display: none;"> The measurement problem is seen as an ambiguity of quantum mechanics, or, beyond that, as a contradiction within the theory: Quantum mechanics offers two conflicting descriptions of the Wigner's-friend experiment. As we argue in this note there are, however, obstacles from within quantum mechanics and regarding our perspective onto doing physics towards fully describing a measurement. We conclude that the ability to exhaustively describe a measurement is an assumption necessary for the common framing of the measurement problem and ensuing suggested solutions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.03248v1-abstract-full').style.display = 'none'; document.getElementById('1912.03248v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1911.11483">arXiv:1911.11483</a> <span> [<a href="https://arxiv.org/pdf/1911.11483">pdf</a>, <a href="https://arxiv.org/ps/1911.11483">ps</a>, <a href="https://arxiv.org/format/1911.11483">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Flow-Area Relations in Immiscible Two-Phase Flow in Porous Media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Roy%2C+S">Subhadeep Roy</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1911.11483v1-abstract-short" style="display: inline;"> We present a theoretical framework for immiscible incompressible two-phase flow in homogeneous porous media that connects the distribution of local fluid velocities to the average seepage velocities. By dividing the pore area along a cross-section transversal to the average flow direction up into differential areas associated with the local flow velocities, we construct a distribution function tha… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.11483v1-abstract-full').style.display = 'inline'; document.getElementById('1911.11483v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1911.11483v1-abstract-full" style="display: none;"> We present a theoretical framework for immiscible incompressible two-phase flow in homogeneous porous media that connects the distribution of local fluid velocities to the average seepage velocities. By dividing the pore area along a cross-section transversal to the average flow direction up into differential areas associated with the local flow velocities, we construct a distribution function that allows us not only to re-establish existing relationships between the seepage velocities of the immiscible fluids, but also to find new relations between their higher moments. We support and demonstrate the formalism through numerical simulations using a dynamic pore-network model for immiscible two-phase flow with two- and three-dimensional pore networks. Our numerical results are in agreement with the theoretical considerations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.11483v1-abstract-full').style.display = 'none'; document.getElementById('1911.11483v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 November, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1911.07490">arXiv:1911.07490</a> <span> [<a href="https://arxiv.org/pdf/1911.07490">pdf</a>, <a href="https://arxiv.org/format/1911.07490">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-ph</span> </div> </div> <p class="title is-5 mathjax"> Pore network modeling of the effects of viscosity ratio and pressure gradient on steady-state incompressible two-phase flow in porous media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Gjennestad%2C+M+A">Magnus Aa. Gjennestad</a>, <a href="/search/physics?searchtype=author&query=Winkler%2C+M">Mathias Winkler</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1911.07490v1-abstract-short" style="display: inline;"> We perform more than 6000 steady-state simulations with a dynamic pore network model, corresponding to a large span in viscosity ratios and capillary numbers. From these simulations, dimensionless quantities such as relative permeabilities, residual saturations, mobility ratios and fractional flows are computed. Relative permeabilities and residual saturations show many of the same qualitative fea… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.07490v1-abstract-full').style.display = 'inline'; document.getElementById('1911.07490v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1911.07490v1-abstract-full" style="display: none;"> We perform more than 6000 steady-state simulations with a dynamic pore network model, corresponding to a large span in viscosity ratios and capillary numbers. From these simulations, dimensionless quantities such as relative permeabilities, residual saturations, mobility ratios and fractional flows are computed. Relative permeabilities and residual saturations show many of the same qualitative features observed in other experimental and modeling studies. However, while other studies find that relative permeabilities converge to straight lines at high capillary numbers we find that this is not the case when viscosity ratios are different from 1. Our conclusion is that departure from straight lines occurs when fluids mix rather than form decoupled flow channels. Another consequence of the mixing is that computed fractional flow curves, plotted against saturation, lie closer to the diagonal than they would otherwise do. At lower capillary numbers, fractional flow curves have a classical S-shape. Ratios of average mobility to their high-capillary number limit values are also considered. These vary, roughly, between 0 and 1, although values larger than 1 are also observed. For a given saturation and viscosity ratio, the mobilities are not always monotonically increasing with the pressure gradient. While increasing the pressure gradient mobilizes more fluid and activates more flow paths, when the mobilized fluid is more viscous, a reduction in average mobility may occur. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.07490v1-abstract-full').style.display = 'none'; document.getElementById('1911.07490v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 November, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1911.02935">arXiv:1911.02935</a> <span> [<a href="https://arxiv.org/pdf/1911.02935">pdf</a>, <a href="https://arxiv.org/ps/1911.02935">ps</a>, <a href="https://arxiv.org/format/1911.02935">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.14.024001">10.1103/PhysRevApplied.14.024001 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Universal methods for suppressing the light shift in atomic clocks using power modulation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Yudin%2C+V+I">V. I. Yudin</a>, <a href="/search/physics?searchtype=author&query=Basalaev%2C+M+Y">M. Yu. Basalaev</a>, <a href="/search/physics?searchtype=author&query=Taichenachev%2C+A+V">A. V. Taichenachev</a>, <a href="/search/physics?searchtype=author&query=Pollock%2C+J+W">J. W. Pollock</a>, <a href="/search/physics?searchtype=author&query=Newman%2C+Z+L">Z. L. Newman</a>, <a href="/search/physics?searchtype=author&query=Shuker%2C+M">M. Shuker</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">A. Hansen</a>, <a href="/search/physics?searchtype=author&query=Hummon%2C+M+T">M. T. Hummon</a>, <a href="/search/physics?searchtype=author&query=Boudot%2C+R">R. Boudot</a>, <a href="/search/physics?searchtype=author&query=Donley%2C+E+A">E. A. Donley</a>, <a href="/search/physics?searchtype=author&query=Kitching%2C+J">J. Kitching</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1911.02935v2-abstract-short" style="display: inline;"> We show that the light shift in atomic clocks can be suppressed using time variation of the interrogation field intensity. By measuring the clock output at two intensity levels, error signals can be generated that simultaneously stabilize a local oscillator to an atomic transition and correct for the shift of this transition caused by the interrogating optical field. These methods are suitable for… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.02935v2-abstract-full').style.display = 'inline'; document.getElementById('1911.02935v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1911.02935v2-abstract-full" style="display: none;"> We show that the light shift in atomic clocks can be suppressed using time variation of the interrogation field intensity. By measuring the clock output at two intensity levels, error signals can be generated that simultaneously stabilize a local oscillator to an atomic transition and correct for the shift of this transition caused by the interrogating optical field. These methods are suitable for optical clocks using one- and two-photon transitions, as well as for microwave clocks based on coherent population trapping or direct interrogation. The proposed methods can be widely used both for high-precision scientific instruments and for a wide range of commercial clocks, including chip-scale atomic clocks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.02935v2-abstract-full').style.display = 'none'; document.getElementById('1911.02935v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 April, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 November, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 14, 024001 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1910.06123">arXiv:1910.06123</a> <span> [<a href="https://arxiv.org/pdf/1910.06123">pdf</a>, <a href="https://arxiv.org/ps/1910.06123">ps</a>, <a href="https://arxiv.org/format/1910.06123">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="History and Philosophy of Physics">physics.hist-ph</span> </div> </div> <p class="title is-5 mathjax"> Measuring Measuring </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Arne Hansen</a>, <a href="/search/physics?searchtype=author&query=Wolf%2C+S">Stefan Wolf</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1910.06123v3-abstract-short" style="display: inline;"> Measurements play a crucial role in doing physics: Their results provide the basis on which we adopt or reject physical theories. In this note, we examine the effect of subjecting measurements themselves to our experience. We require that our contact with the world is empirically warranted. Therefore, we study theories that satisfy the following assumption: Interactions are accounted for so that t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.06123v3-abstract-full').style.display = 'inline'; document.getElementById('1910.06123v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1910.06123v3-abstract-full" style="display: none;"> Measurements play a crucial role in doing physics: Their results provide the basis on which we adopt or reject physical theories. In this note, we examine the effect of subjecting measurements themselves to our experience. We require that our contact with the world is empirically warranted. Therefore, we study theories that satisfy the following assumption: Interactions are accounted for so that they are empirically traceable, and observations necessarily go with such an interaction with the observed system. Examining, with regard to these assumptions, an abstract representation of measurements with tools from quantum logic leads us to contextual theories. Contextuality becomes a means to render interactions, thus also measurements, empirically tangible. The measurement becomes problematic---also beyond quantum mechanics---if one tries to commensurate the assumption of tangible interactions with the notion of a spectator theory, i.e., with the idea that measurement results are read off without effect. The problem, thus, presents itself as the collision of different epistemological stances with repercussions beyond quantum mechanics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.06123v3-abstract-full').style.display = 'none'; document.getElementById('1910.06123v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 October, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1909.01672">arXiv:1909.01672</a> <span> [<a href="https://arxiv.org/pdf/1909.01672">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Medical Physics">physics.med-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Image and Video Processing">eess.IV</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1361-6560/ab63b7">10.1088/1361-6560/ab63b7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Compressed Sensing MRI With Variable Density Averaging (CS-VDA) Outperforms Full Sampling At Low SNR </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Schoormans%2C+J">Jasper Schoormans</a>, <a href="/search/physics?searchtype=author&query=Strijkers%2C+G+J">Gustav J. Strijkers</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A+C">Anders C. Hansen</a>, <a href="/search/physics?searchtype=author&query=Nederveen%2C+A+J">Aart J. Nederveen</a>, <a href="/search/physics?searchtype=author&query=Coolen%2C+B+F">Bram F. Coolen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1909.01672v1-abstract-short" style="display: inline;"> We investigated whether a combination of k-space undersampling and variable density averaging enhances image quality for low-SNR MRI acquisitions. We implemented 3D Cartesian k-space prospective undersampling with a variable number of averages for each k-line. The performance of this compressed sensing with variable-density averaging (CS-VDA) method was evaluated in retrospective analysis of fully… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1909.01672v1-abstract-full').style.display = 'inline'; document.getElementById('1909.01672v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1909.01672v1-abstract-full" style="display: none;"> We investigated whether a combination of k-space undersampling and variable density averaging enhances image quality for low-SNR MRI acquisitions. We implemented 3D Cartesian k-space prospective undersampling with a variable number of averages for each k-line. The performance of this compressed sensing with variable-density averaging (CS-VDA) method was evaluated in retrospective analysis of fully sampled phantom MRI measurements, as well as for prospectively accelerated in vivo 3D brain and knee MRI scans. Both phantom and in vivo results showed that acquisitions using the CS-VDA approach resulted in better image quality as compared to full sampling of k-space in the same scan time. Specifically, CS-VDA with a higher number of averages in the center of k-space resulted in the best image quality, apparent from increased anatomical detail with preserved soft-tissue contrast. This novel approach will facilitate improved image quality of inherently low SNR data, such as those with high-resolution or specific contrast-weightings with low SNR efficiency. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1909.01672v1-abstract-full').style.display = 'none'; document.getElementById('1909.01672v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 September, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physics in Medicine & Biology 65.4 (2020): 045004 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1907.12842">arXiv:1907.12842</a> <span> [<a href="https://arxiv.org/pdf/1907.12842">pdf</a>, <a href="https://arxiv.org/format/1907.12842">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-ph</span> </div> </div> <p class="title is-5 mathjax"> A Dynamic Network Simulator for Immiscible Two-Phase Flow in Porous Media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Gjennestad%2C+M+A">Magnus Aa. Gjennestad</a>, <a href="/search/physics?searchtype=author&query=Vassvik%2C+M">Morten Vassvik</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1907.12842v1-abstract-short" style="display: inline;"> We present in detail a set of algorithms to carry out fluid displacements in a dynamic pore-network model of immiscible two-phase flow in porous media. The algorithms are general and applicable to regular and irregular pore networks in two and three dimensions with different boundary conditions. Implementing these sets of algorithms, we describe a dynamic pore-network model and reproduce some of t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.12842v1-abstract-full').style.display = 'inline'; document.getElementById('1907.12842v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1907.12842v1-abstract-full" style="display: none;"> We present in detail a set of algorithms to carry out fluid displacements in a dynamic pore-network model of immiscible two-phase flow in porous media. The algorithms are general and applicable to regular and irregular pore networks in two and three dimensions with different boundary conditions. Implementing these sets of algorithms, we describe a dynamic pore-network model and reproduce some of the fundamental properties of both the transient and steady-state two-phase flow. During drainage displacements, we show that the model can reproduce the flow patterns corresponding to viscous fingering, capillary fingering and stable displacement by altering the capillary number and the viscosity ratio. In steady-state flow, the model verifies the linear to non-linear transition of the effective rheological properties and satisfy the relations between the seepage velocities of two-phase flow in porous media. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.12842v1-abstract-full').style.display = 'none'; document.getElementById('1907.12842v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 July, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">24 pages, 17 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1905.00295">arXiv:1905.00295</a> <span> [<a href="https://arxiv.org/pdf/1905.00295">pdf</a>, <a href="https://arxiv.org/ps/1905.00295">ps</a>, <a href="https://arxiv.org/format/1905.00295">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="History and Philosophy of Physics">physics.hist-ph</span> </div> </div> <p class="title is-5 mathjax"> No master (key) No (measurement) problem </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Arne Hansen</a>, <a href="/search/physics?searchtype=author&query=Wolf%2C+S">Stefan Wolf</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1905.00295v1-abstract-short" style="display: inline;"> Can normal science-in the Kuhnian sense-add something substantial to the discussion about the measurement problem? Does an extended Wigner's-friend Gedankenexperiment illustrate new issues? Or a new quality of known issues? Are we led to new interpretations, new perspectives, or do we iterate the previously known? The recent debate does, as we argue, neither constitute a turning point in the discu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.00295v1-abstract-full').style.display = 'inline'; document.getElementById('1905.00295v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1905.00295v1-abstract-full" style="display: none;"> Can normal science-in the Kuhnian sense-add something substantial to the discussion about the measurement problem? Does an extended Wigner's-friend Gedankenexperiment illustrate new issues? Or a new quality of known issues? Are we led to new interpretations, new perspectives, or do we iterate the previously known? The recent debate does, as we argue, neither constitute a turning point in the discussion about the measurement problem nor fundamentally challenge the legitimacy of quantum mechanics. Instead, the measurement problem asks for a reflection on fundamental paradigms of doing physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.00295v1-abstract-full').style.display = 'none'; document.getElementById('1905.00295v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 April, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1904.04653">arXiv:1904.04653</a> <span> [<a href="https://arxiv.org/pdf/1904.04653">pdf</a>, <a href="https://arxiv.org/ps/1904.04653">ps</a>, <a href="https://arxiv.org/format/1904.04653">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Effective Rheology of Bi-Viscous Non-Newtonian Fluids in Porous Media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Talon%2C+L">Laurent Talon</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1904.04653v1-abstract-short" style="display: inline;"> We model the flow of a bi-viscous non-Newtonian fluid in a porous medium by a square lattice where the links obey a piece-wise linear constitutive equation. We find numerically that the flow regime where the network transitions from all links behaving according to the first linear part of the constitutive equation to all links behaving according to the second linear part of the constitutive equati… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.04653v1-abstract-full').style.display = 'inline'; document.getElementById('1904.04653v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1904.04653v1-abstract-full" style="display: none;"> We model the flow of a bi-viscous non-Newtonian fluid in a porous medium by a square lattice where the links obey a piece-wise linear constitutive equation. We find numerically that the flow regime where the network transitions from all links behaving according to the first linear part of the constitutive equation to all links behaving according to the second linear part of the constitutive equation, is characterized by a critical point. We measure two critical exponents associated with this critical point, one of the being the correlation length exponent. We find that both critical exponents depend on the parameters of the model. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.04653v1-abstract-full').style.display = 'none'; document.getElementById('1904.04653v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 April, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to Frontiers in Physics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1902.07577">arXiv:1902.07577</a> <span> [<a href="https://arxiv.org/pdf/1902.07577">pdf</a>, <a href="https://arxiv.org/format/1902.07577">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3389/fphy.2019.00092">10.3389/fphy.2019.00092 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Effective rheology of two-phase flow in a capillary fiber bundle model </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Roy%2C+S">Subhadeep Roy</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1902.07577v2-abstract-short" style="display: inline;"> We investigate the effective rheology of two-phase flow in a bundle of parallel capillary tubes carrying two immiscible fluids under an external pressure drop. The diameter of each tube varies along its length and the corresponding capillary threshold pressures are considered to be distributed randomly according to a uniform probability distribution. We demonstrate through analytical calculations… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.07577v2-abstract-full').style.display = 'inline'; document.getElementById('1902.07577v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1902.07577v2-abstract-full" style="display: none;"> We investigate the effective rheology of two-phase flow in a bundle of parallel capillary tubes carrying two immiscible fluids under an external pressure drop. The diameter of each tube varies along its length and the corresponding capillary threshold pressures are considered to be distributed randomly according to a uniform probability distribution. We demonstrate through analytical calculations that a transition from a linear Darcy regime to a non-linear behavior occurs while decreasing the pressure drop $螖P$, where the total flow rate $\langle Q \rangle$ varies with $螖P$ with an exponent $2$. This exponent for the non-linear regime changes when a lower cut-off $P_m$ is introduced in the threshold distribution. We demonstrate analytically that, in the limit where $螖P$ approaches $P_m$, the flow rate scales as $\langle Q \rangle \sim (|螖P|-P_m)^{3/2}$. We have also provided some numerical results in support to our analytical findings. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.07577v2-abstract-full').style.display = 'none'; document.getElementById('1902.07577v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 September, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 February, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 2 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Front. Phys. 7: 92 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1812.00106">arXiv:1812.00106</a> <span> [<a href="https://arxiv.org/pdf/1812.00106">pdf</a>, <a href="https://arxiv.org/ps/1812.00106">ps</a>, <a href="https://arxiv.org/format/1812.00106">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.12.014019">10.1103/PhysRevApplied.12.014019 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multi-axis atom interferometer gyroscope with a single source of atoms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Chen%2C+Y">Yun-Jhih Chen</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Azure Hansen</a>, <a href="/search/physics?searchtype=author&query=Hoth%2C+G+W">Gregory W. Hoth</a>, <a href="/search/physics?searchtype=author&query=Ivanov%2C+E">Eugene Ivanov</a>, <a href="/search/physics?searchtype=author&query=Pelle%2C+B">Bruno Pelle</a>, <a href="/search/physics?searchtype=author&query=Kitching%2C+J">John Kitching</a>, <a href="/search/physics?searchtype=author&query=Donley%2C+E+A">Elizabeth A. Donley</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1812.00106v1-abstract-short" style="display: inline;"> Using the technique of point source atom interferometry, we characterize the sensitivity of a multi-axis gyroscope based on free-space Raman interrogation of a single source of cold atoms in a glass vacuum cell. The instrument simultaneously measures the acceleration in the direction of the Raman laser beams and the component of the rotation vector in the plane perpendicular to that direction. We… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.00106v1-abstract-full').style.display = 'inline'; document.getElementById('1812.00106v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1812.00106v1-abstract-full" style="display: none;"> Using the technique of point source atom interferometry, we characterize the sensitivity of a multi-axis gyroscope based on free-space Raman interrogation of a single source of cold atoms in a glass vacuum cell. The instrument simultaneously measures the acceleration in the direction of the Raman laser beams and the component of the rotation vector in the plane perpendicular to that direction. We characterize the sensitivities for the magnitude and direction of the rotation vector measurement, which are 0.033 $^{\circ}/\mathrm{s}$ and 0.27 $^{\circ}$ with one second averaging time, respectively. The sensitivity could be improved by increasing the Raman interrogation time, allowing the cold-atom cloud to expand further, correcting the fluctuations in the initial cloud shape, and reducing sources of technical noise. The unique ability of the PSI technique to measure the rotation vector in a plane may permit applications of atom interferometry such as tracking the precession of a rotation vector and gyrocompassing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.00106v1-abstract-full').style.display = 'none'; document.getElementById('1812.00106v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 November, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 12, 014019 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1810.04573">arXiv:1810.04573</a> <span> [<a href="https://arxiv.org/pdf/1810.04573">pdf</a>, <a href="https://arxiv.org/ps/1810.04573">ps</a>, <a href="https://arxiv.org/format/1810.04573">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="History and Philosophy of Physics">physics.hist-ph</span> </div> </div> <p class="title is-5 mathjax"> The Measurement Problem Is the "Measurement" Problem </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Arne Hansen</a>, <a href="/search/physics?searchtype=author&query=Wolf%2C+S">Stefan Wolf</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1810.04573v2-abstract-short" style="display: inline;"> The term "measurement" in quantum theory (as well as in other physical theories) is ambiguous: It is used to describe both an experience - e.g., an observation in an experiment - and an interaction with the system under scrutiny. If doing physics is regarded as a creative activity to develop a meaningful description of the world, then one has to carefully discriminate between the two notions: An o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.04573v2-abstract-full').style.display = 'inline'; document.getElementById('1810.04573v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1810.04573v2-abstract-full" style="display: none;"> The term "measurement" in quantum theory (as well as in other physical theories) is ambiguous: It is used to describe both an experience - e.g., an observation in an experiment - and an interaction with the system under scrutiny. If doing physics is regarded as a creative activity to develop a meaningful description of the world, then one has to carefully discriminate between the two notions: An observer's account of experience - consitutive to meaning - is hardly expressed exhaustively by the formal framework of an interaction within one particular theory. We develop a corresponding perspective onto central terms in quantum mechanics in general, and onto the measurement problem in particular. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.04573v2-abstract-full').style.display = 'none'; document.getElementById('1810.04573v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 April, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 October, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2018. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1809.10378">arXiv:1809.10378</a> <span> [<a href="https://arxiv.org/pdf/1809.10378">pdf</a>, <a href="https://arxiv.org/format/1809.10378">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3389/fphy.2018.00150">10.3389/fphy.2018.00150 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Non-isothermal transport of multi-phase fluids in porous media. Constitutive equations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kjelstrup%2C+S">Signe Kjelstrup</a>, <a href="/search/physics?searchtype=author&query=Bedeaux%2C+D">Dick Bedeaux</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Hafskjold%2C+B">Bj酶rn Hafskjold</a>, <a href="/search/physics?searchtype=author&query=Galteland%2C+O">Olav Galteland</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1809.10378v1-abstract-short" style="display: inline;"> We develop constitutive equations for multi-component, multi-phase, macro-scale flow in a porous medium exposed to temperature-, composition-, and pressure -gradients. The porous medium is non-deformable. We define the pressure and the composition of the representative elementary volume (REV) in terms of the volume and surface averaged pressure and the saturation, and the respective driving forces… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.10378v1-abstract-full').style.display = 'inline'; document.getElementById('1809.10378v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1809.10378v1-abstract-full" style="display: none;"> We develop constitutive equations for multi-component, multi-phase, macro-scale flow in a porous medium exposed to temperature-, composition-, and pressure -gradients. The porous medium is non-deformable. We define the pressure and the composition of the representative elementary volume (REV) in terms of the volume and surface averaged pressure and the saturation, and the respective driving forces from these variables. New contributions due to varying porosity or surface tension offer explanations for non-Darcy behavior. The interaction of a thermal and mechanical driving forces give thermal osmosis. An experimental program is suggested to verify Onsager symmetry in the transport coefficients. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.10378v1-abstract-full').style.display = 'none'; document.getElementById('1809.10378v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 September, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">22 pages, 2 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1805.03943">arXiv:1805.03943</a> <span> [<a href="https://arxiv.org/pdf/1805.03943">pdf</a>, <a href="https://arxiv.org/format/1805.03943">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3389/fphy.2018.00126">10.3389/fphy.2018.00126 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Non-isothermal transport of multi-phase fluids in porous media. The entropy production </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Kjelstrup%2C+S">Signe Kjelstrup</a>, <a href="/search/physics?searchtype=author&query=Bedeaux%2C+D">Dick Bedeaux</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Hafskjold%2C+B">Bj酶rn Hafskjold</a>, <a href="/search/physics?searchtype=author&query=Galteland%2C+O">Olav Galteland</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1805.03943v1-abstract-short" style="display: inline;"> We derive the entropy production for transport of multi-phase fluids in a non-deformable, porous medium exposed to differences in pressure, temperature, and chemical potentials. Thermodynamic extensive variables on the macro-scale are obtained by integrating over a representative elementary volume (REV). Using Euler homogeneity of the first order, we obtain the Gibbs equation for the REV. From thi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.03943v1-abstract-full').style.display = 'inline'; document.getElementById('1805.03943v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1805.03943v1-abstract-full" style="display: none;"> We derive the entropy production for transport of multi-phase fluids in a non-deformable, porous medium exposed to differences in pressure, temperature, and chemical potentials. Thermodynamic extensive variables on the macro-scale are obtained by integrating over a representative elementary volume (REV). Using Euler homogeneity of the first order, we obtain the Gibbs equation for the REV. From this we define the intensive variables, the temperature, pressure and chemical potentials and, using the balance equations, derive the entropy production for the REV. The entropy production defines sets of independent conjugate thermodynamic fluxes and forces in the standard way. The transport of two-phase flow of immiscible components is used to illustrate the equations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.03943v1-abstract-full').style.display = 'none'; document.getElementById('1805.03943v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 May, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">25 pages, 7 figures, Talk at Interpore, New Orleans, 2018</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1802.00691">arXiv:1802.00691</a> <span> [<a href="https://arxiv.org/pdf/1802.00691">pdf</a>, <a href="https://arxiv.org/format/1802.00691">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3389/fphy.2018.00056">10.3389/fphy.2018.00056 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Stable and efficient time integration of a dynamic pore network model for two-phase flow in porous media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Gjennestad%2C+M+A">Magnus Aa. Gjennestad</a>, <a href="/search/physics?searchtype=author&query=Vassvik%2C+M">Morten Vassvik</a>, <a href="/search/physics?searchtype=author&query=Kjelstrup%2C+S">Signe Kjelstrup</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1802.00691v3-abstract-short" style="display: inline;"> We study three different time integration methods for a dynamic pore network model for immiscible two-phase flow in porous media. Considered are two explicit methods, the forward Euler and midpoint methods, and a new semi-implicit method developed herein. The explicit methods are known to suffer from numerical instabilities at low capillary numbers. A new time-step criterion is suggested in order… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.00691v3-abstract-full').style.display = 'inline'; document.getElementById('1802.00691v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1802.00691v3-abstract-full" style="display: none;"> We study three different time integration methods for a dynamic pore network model for immiscible two-phase flow in porous media. Considered are two explicit methods, the forward Euler and midpoint methods, and a new semi-implicit method developed herein. The explicit methods are known to suffer from numerical instabilities at low capillary numbers. A new time-step criterion is suggested in order to stabilize them. Numerical experiments, including a Haines jump case, are performed and these demonstrate that stabilization is achieved. Further, the results from the Haines jump case are consistent with experimental observations. A performance analysis reveals that the semi-implicit method is able to perform stable simulations with much less computational effort than the explicit methods at low capillary numbers. The relative benefit of using the semi-implicit method increases with decreasing capillary number $\mathrm{Ca}$, and at $\mathrm{Ca} \sim 10^{-8}$ the computational time needed is reduced by three orders of magnitude. This increased efficiency enables simulations in the low-capillary number regime that are unfeasible with explicit methods and the range of capillary numbers for which the pore network model is a tractable modeling alternative is thus greatly extended by the semi-implicit method. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.00691v3-abstract-full').style.display = 'none'; document.getElementById('1802.00691v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 July, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 February, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">33 pages, 12 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Frontiers in Physics 6 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1802.00668">arXiv:1802.00668</a> <span> [<a href="https://arxiv.org/pdf/1802.00668">pdf</a>, <a href="https://arxiv.org/ps/1802.00668">ps</a>, <a href="https://arxiv.org/format/1802.00668">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Soft Condensed Matter">cond-mat.soft</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> </div> <p class="title is-5 mathjax"> A Renormalization Group Procedure for Fiber Bundle Models </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Pradhan%2C+S">Srutarshi Pradhan</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Ray%2C+P">Purusattam Ray</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1802.00668v2-abstract-short" style="display: inline;"> We introduce two versions of a renormalization group scheme for the equal load sharing fiber bundle model. The renormalization group is based on formulating the fiber bundle model in the language of damage mechanics. A central concept is the work performed on the fiber bundle to produce a given damage. The renormalization group conserves this work. In the first version of the renormalization group… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.00668v2-abstract-full').style.display = 'inline'; document.getElementById('1802.00668v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1802.00668v2-abstract-full" style="display: none;"> We introduce two versions of a renormalization group scheme for the equal load sharing fiber bundle model. The renormalization group is based on formulating the fiber bundle model in the language of damage mechanics. A central concept is the work performed on the fiber bundle to produce a given damage. The renormalization group conserves this work. In the first version of the renormalization group, we take advantage of ordering the strength of the individual fibers. This procedure, which is the simpler one, gives EXACT results -but cannot be generalized to other fiber bundle models such as the local load sharing one. The second renormalization group scheme based on the physical location of the individual fibers may be generalized to other fiber bundle models. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.00668v2-abstract-full').style.display = 'none'; document.getElementById('1802.00668v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 March, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 February, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 12 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1712.06826">arXiv:1712.06826</a> <span> [<a href="https://arxiv.org/pdf/1712.06826">pdf</a>, <a href="https://arxiv.org/ps/1712.06826">ps</a>, <a href="https://arxiv.org/format/1712.06826">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Rheology of High-Capillary Number Flow in Porous Media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Gjennestad%2C+M+A">Magnus Aa. Gjennestad</a>, <a href="/search/physics?searchtype=author&query=Vassvik%2C+M">Morten Vassvik</a>, <a href="/search/physics?searchtype=author&query=Winkler%2C+M">Mathias Winkler</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Flekk%C3%B8y%2C+E+G">Eirik G. Flekk酶y</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1712.06826v1-abstract-short" style="display: inline;"> Immiscible fluids flowing at high capillary numbers in porous media may be characterized by an effective viscosity. We demonstrate that the effective viscosity is well described by the Lichtenecker-Rother equation. The exponent $伪$ in this equation takes either the value 1 or 0.6 in two- and 0.5 in three-dimensional systems depending on the pore geometry. Our arguments are based on analytical and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1712.06826v1-abstract-full').style.display = 'inline'; document.getElementById('1712.06826v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1712.06826v1-abstract-full" style="display: none;"> Immiscible fluids flowing at high capillary numbers in porous media may be characterized by an effective viscosity. We demonstrate that the effective viscosity is well described by the Lichtenecker-Rother equation. The exponent $伪$ in this equation takes either the value 1 or 0.6 in two- and 0.5 in three-dimensional systems depending on the pore geometry. Our arguments are based on analytical and numerical methods. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1712.06826v1-abstract-full').style.display = 'none'; document.getElementById('1712.06826v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 December, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1712.06823">arXiv:1712.06823</a> <span> [<a href="https://arxiv.org/pdf/1712.06823">pdf</a>, <a href="https://arxiv.org/ps/1712.06823">ps</a>, <a href="https://arxiv.org/format/1712.06823">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Relations between Seepage Velocities in Immiscible, Incompressible Two-Phase Flow in Porous Media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Bedeaux%2C+D">Dick Bedeaux</a>, <a href="/search/physics?searchtype=author&query=Kjelstrup%2C+S">Signe Kjelstrup</a>, <a href="/search/physics?searchtype=author&query=Gjennestad%2C+M+A">Magnus Aa. Gjennestad</a>, <a href="/search/physics?searchtype=author&query=Vassvik%2C+M">Morten Vassvik</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1712.06823v1-abstract-short" style="display: inline;"> Based on thermodynamic considerations we derive a set of equations relating the seepage velocities of the fluid components in immiscible and incompressible two-phase flow in porous media. They necessitate the introduction of a new velocity function, the co-moving velocity. This velocity function is a characteristic of the porous medium. Together with a constitutive relation between the velocities… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1712.06823v1-abstract-full').style.display = 'inline'; document.getElementById('1712.06823v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1712.06823v1-abstract-full" style="display: none;"> Based on thermodynamic considerations we derive a set of equations relating the seepage velocities of the fluid components in immiscible and incompressible two-phase flow in porous media. They necessitate the introduction of a new velocity function, the co-moving velocity. This velocity function is a characteristic of the porous medium. Together with a constitutive relation between the velocities and the driving forces, such as the pressure gradient, these equations form a closed set. We solve four versions of the capillary tube model analytically using this theory. We test the theory numerically on a network model. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1712.06823v1-abstract-full').style.display = 'none'; document.getElementById('1712.06823v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 December, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">This work is a major advancement from the previous work presented in arXiv:1605.02874v2. 27 pages, 7 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1612.06101">arXiv:1612.06101</a> <span> [<a href="https://arxiv.org/pdf/1612.06101">pdf</a>, <a href="https://arxiv.org/format/1612.06101">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> Effective Rheology of Two-phase Flow in Three-Dimensional Porous Media: Experiment and Simulation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Bender%2C+A+T">Andrew T. Bender</a>, <a href="/search/physics?searchtype=author&query=Danczyk%2C+M">Matthew Danczyk</a>, <a href="/search/physics?searchtype=author&query=Keepseagle%2C+K">Kayla Keepseagle</a>, <a href="/search/physics?searchtype=author&query=Prather%2C+C+A">Cody A. Prather</a>, <a href="/search/physics?searchtype=author&query=Bray%2C+J+M">Joshua M. Bray</a>, <a href="/search/physics?searchtype=author&query=Thrane%2C+L+W">Linn W. Thrane</a>, <a href="/search/physics?searchtype=author&query=Seymour%2C+J+D">Joseph D Seymour</a>, <a href="/search/physics?searchtype=author&query=Codd%2C+S+L">Sarah L Codd</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1612.06101v1-abstract-short" style="display: inline;"> We present an experimental and numerical study of immiscible two-phase flow in 3-dimensional (3D) porous media to find the relationship between the volumetric flow rate ($Q$) and the total pressure difference ($螖P$) in the steady state. We show that in the regime where capillary forces compete with the viscous forces, the distribution of capillary barriers at the interfaces effectively creates a y… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.06101v1-abstract-full').style.display = 'inline'; document.getElementById('1612.06101v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1612.06101v1-abstract-full" style="display: none;"> We present an experimental and numerical study of immiscible two-phase flow in 3-dimensional (3D) porous media to find the relationship between the volumetric flow rate ($Q$) and the total pressure difference ($螖P$) in the steady state. We show that in the regime where capillary forces compete with the viscous forces, the distribution of capillary barriers at the interfaces effectively creates a yield threshold, making the fluids reminiscent of a Bingham viscoplastic fluid in the porous medium, introducing a threshold pressure $P_t$. In this regime, $Q$ depends quadratically on an excess pressure drop ($螖P-P_t$). While increasing the flow-rate, there is a transition, beyond which the flow is Newtonian and the relationship is linear. In our experiments, we build a model porous medium using a column of glass beads transporting two fluids -- de-ionized water and air. For the numerical study, reconstructed 3D pore-networks from real core samples are considered and the transport of wetting and non-wetting fluids through the network are modeled by tracking the fluid interfaces with time. We find agreement between our numerical and experimental results. Our results match the mean-field results reported earlier. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.06101v1-abstract-full').style.display = 'none'; document.getElementById('1612.06101v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 December, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 8 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1606.09339">arXiv:1606.09339</a> <span> [<a href="https://arxiv.org/pdf/1606.09339">pdf</a>, <a href="https://arxiv.org/ps/1606.09339">ps</a>, <a href="https://arxiv.org/format/1606.09339">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> A Monte Carlo Algorithm for Immiscible Two-Phase Flow in Porous Media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Savani%2C+I">Isha Savani</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Bedeaux%2C+D">Dick Bedeaux</a>, <a href="/search/physics?searchtype=author&query=Kjelstrup%2C+S">Signe Kjelstrup</a>, <a href="/search/physics?searchtype=author&query=Vassvik%2C+M">Morten Vassvik</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1606.09339v2-abstract-short" style="display: inline;"> We present a Markov Chain Monte Carlo algorithm based on the Metropolis algorithm for simulation of the flow of two immiscible fluids in a porous medium under macroscopic steady-state conditions using a dynamical pore network model that tracks the motion of the fluid interfaces. The Monte Carlo algorithm is based on the configuration probability, where a configuration is defined by the positions o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1606.09339v2-abstract-full').style.display = 'inline'; document.getElementById('1606.09339v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1606.09339v2-abstract-full" style="display: none;"> We present a Markov Chain Monte Carlo algorithm based on the Metropolis algorithm for simulation of the flow of two immiscible fluids in a porous medium under macroscopic steady-state conditions using a dynamical pore network model that tracks the motion of the fluid interfaces. The Monte Carlo algorithm is based on the configuration probability, where a configuration is defined by the positions of all fluid interfaces. We show that the configuration probability is proportional to the inverse of the flow rate. Using a two-dimensional network, advancing the interfaces using time integration the computational time scales as the linear system size to the fourth power, whereas the Monte Carlo computational time scales as the linear size to the second power. We discuss the strengths and the weaknesses of the algorithm. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1606.09339v2-abstract-full').style.display = 'none'; document.getElementById('1606.09339v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 December, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 June, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">22 pages, 15 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1606.02569">arXiv:1606.02569</a> <span> [<a href="https://arxiv.org/pdf/1606.02569">pdf</a>, <a href="https://arxiv.org/format/1606.02569">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevE.95.023116">10.1103/PhysRevE.95.023116 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ensemble Distribution for Immiscible Two-Phase Flow in Porous Media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Savani%2C+I">Isha Savani</a>, <a href="/search/physics?searchtype=author&query=Bedeaux%2C+D">Dick Bedeaux</a>, <a href="/search/physics?searchtype=author&query=Kjelstrup%2C+S">Signe Kjelstrup</a>, <a href="/search/physics?searchtype=author&query=Vassvik%2C+M">Morten Vassvik</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1606.02569v2-abstract-short" style="display: inline;"> We construct an ensemble distribution to describe steady immiscible two-phase flow of two incompressible fluids in a porous medium. The system is found to be ergodic. The distribution is used to compute macroscopic flow parameters. In particular, we find an expression for the overall mobility of the system from the ensemble distribution. The entropy production at the scale of the porous medium is… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1606.02569v2-abstract-full').style.display = 'inline'; document.getElementById('1606.02569v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1606.02569v2-abstract-full" style="display: none;"> We construct an ensemble distribution to describe steady immiscible two-phase flow of two incompressible fluids in a porous medium. The system is found to be ergodic. The distribution is used to compute macroscopic flow parameters. In particular, we find an expression for the overall mobility of the system from the ensemble distribution. The entropy production at the scale of the porous medium is shown to give the expected product of the average flow and its driving force, obtained from a black-box description. We test numerically some of the central theoretical results. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1606.02569v2-abstract-full').style.display = 'none'; document.getElementById('1606.02569v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 December, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 June, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 pages, 9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. E 95, 023116 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1605.02874">arXiv:1605.02874</a> <span> [<a href="https://arxiv.org/pdf/1605.02874">pdf</a>, <a href="https://arxiv.org/ps/1605.02874">ps</a>, <a href="https://arxiv.org/format/1605.02874">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> </div> </div> <p class="title is-5 mathjax"> A new set of equations describing immiscible two-phase flow in isotropic porous media </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Bedeaux%2C+D">Dick Bedeaux</a>, <a href="/search/physics?searchtype=author&query=Kjelstrup%2C+S">Signe Kjelstrup</a>, <a href="/search/physics?searchtype=author&query=Savani%2C+I">Isha Savani</a>, <a href="/search/physics?searchtype=author&query=Vassvik%2C+M">Morten Vassvik</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1605.02874v2-abstract-short" style="display: inline;"> Based on non-equilibrium thermodynamics we derive a set of general equations relating the partial volumetric flow rates to each other and to the total volumetric flow rate in immiscible two-phase flow in porous media. These equations together with the conservation of saturation reduces the immiscible two-phase flow problem to a single-phase flow problem of a complex fluid. We discuss the new equat… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1605.02874v2-abstract-full').style.display = 'inline'; document.getElementById('1605.02874v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1605.02874v2-abstract-full" style="display: none;"> Based on non-equilibrium thermodynamics we derive a set of general equations relating the partial volumetric flow rates to each other and to the total volumetric flow rate in immiscible two-phase flow in porous media. These equations together with the conservation of saturation reduces the immiscible two-phase flow problem to a single-phase flow problem of a complex fluid. We discuss the new equation in terms of the relative permeability equations. We test the equations on model systems, both analytically and numerically. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1605.02874v2-abstract-full').style.display = 'none'; document.getElementById('1605.02874v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 December, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 May, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">22 pages, 7 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1601.00327">arXiv:1601.00327</a> <span> [<a href="https://arxiv.org/pdf/1601.00327">pdf</a>, <a href="https://arxiv.org/format/1601.00327">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1080/09500340.2016.1139204">10.1080/09500340.2016.1139204 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Raman fingerprints on the Bloch sphere of a spinor Bose-Einstein condensate </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Schultz%2C+J+T">Justin T. Schultz</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Azure Hansen</a>, <a href="/search/physics?searchtype=author&query=Murphree%2C+J+D">Joseph D. Murphree</a>, <a href="/search/physics?searchtype=author&query=Jayaseelan%2C+M">Maitreyi Jayaseelan</a>, <a href="/search/physics?searchtype=author&query=Bigelow%2C+N+P">Nicholas P. Bigelow</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1601.00327v2-abstract-short" style="display: inline;"> We explore the geometric interpretation of a diabatic, two-photon Raman process as a rotation on the Bloch sphere for a pseudo-spin-1/2 system. The spin state of a spin-1/2 quantum system can be described by a point on the surface of the Bloch sphere, and its evolution during a Raman pulse is a trajectory on the sphere determined by properties of the optical beams: the pulse area, the relative int… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1601.00327v2-abstract-full').style.display = 'inline'; document.getElementById('1601.00327v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1601.00327v2-abstract-full" style="display: none;"> We explore the geometric interpretation of a diabatic, two-photon Raman process as a rotation on the Bloch sphere for a pseudo-spin-1/2 system. The spin state of a spin-1/2 quantum system can be described by a point on the surface of the Bloch sphere, and its evolution during a Raman pulse is a trajectory on the sphere determined by properties of the optical beams: the pulse area, the relative intensities and phases, and the relative frequencies. We experimentally demonstrate key features of this model with a $^{87}$Rb spinor Bose-Einstein condensate, which allows us to examine spatially dependent signatures of the Raman beams. The two-photon detuning allows us to precisely control the spin density and imprinted relative phase profiles, as we show with a coreless vortex. With this comprehensive understanding and intuitive geometric interpretation, we use the Raman process to create and tailor as well as study and characterize exotic topological spin textures in spinor BECs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1601.00327v2-abstract-full').style.display = 'none'; document.getElementById('1601.00327v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 January, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 January, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 13 figures, submitted to the Journal of Modern Optics "20 Years of Bose-Einstein condensates" Special Issue</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1509.07444">arXiv:1509.07444</a> <span> [<a href="https://arxiv.org/pdf/1509.07444">pdf</a>, <a href="https://arxiv.org/format/1509.07444">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1021/acs.jpclett.5b02178">10.1021/acs.jpclett.5b02178 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Selective electrochemical generation of hydrogen peroxide from water oxidation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Viswanathan%2C+V">Venkatasubramanian Viswanathan</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+H+A">Heine A. Hansen</a>, <a href="/search/physics?searchtype=author&query=N%C3%B8rskov%2C+J+K">Jens K. N酶rskov</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1509.07444v1-abstract-short" style="display: inline;"> Water is a life-giving source, fundamental to human existence, yet, over a billion people lack access to clean drinking water. Present techniques for water treatment such as piped, treated water rely on time and resource intensive centralized solutions. In this work, we propose a decentralized device concept that can utilize sunlight to split water into hydrogen and hydrogen peroxide. The hydrogen… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1509.07444v1-abstract-full').style.display = 'inline'; document.getElementById('1509.07444v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1509.07444v1-abstract-full" style="display: none;"> Water is a life-giving source, fundamental to human existence, yet, over a billion people lack access to clean drinking water. Present techniques for water treatment such as piped, treated water rely on time and resource intensive centralized solutions. In this work, we propose a decentralized device concept that can utilize sunlight to split water into hydrogen and hydrogen peroxide. The hydrogen peroxide can oxidize organics while the hydrogen bubbles out. In enabling this device, we require an electrocatalyst that can oxidize water while suppressing the thermodynamically favored oxygen evolution and form hydrogen peroxide. Using density functional theory calculations, we show that the free energy of adsorbed OH$^*$ can be used as a descriptor to screen for selectivity trends between the 2e$^-$ water oxidation to H$_2$O$_2$ and the 4e$^-$ oxidation to O$_2$. We show that materials that bind oxygen intermediates sufficiently weakly, such as SnO$_2$, can activate hydrogen peroxide evolution. We present a rational design principle for the selectivity in electrochemical water oxidation and identify new material candidates that could perform H$_2$O$_2$ evolution selectively. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1509.07444v1-abstract-full').style.display = 'none'; document.getElementById('1509.07444v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 September, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 3 figures, 6 pages supporting information</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Phys. Chem. Lett., 2015, 6, 4224-4228 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1507.06198">arXiv:1507.06198</a> <span> [<a href="https://arxiv.org/pdf/1507.06198">pdf</a>, <a href="https://arxiv.org/ps/1507.06198">ps</a>, <a href="https://arxiv.org/format/1507.06198">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Fluid Dynamics">physics.flu-dyn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Soft Condensed Matter">cond-mat.soft</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-ph</span> </div> </div> <p class="title is-5 mathjax"> Dynamic wettability alteration in immiscible two-phase flow in porous media: Effect on transport properties and critical slowing down </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Flovik%2C+V">Vegard Flovik</a>, <a href="/search/physics?searchtype=author&query=Sinha%2C+S">Santanu Sinha</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1507.06198v1-abstract-short" style="display: inline;"> The change in contact angles due to the injection of low salinity water or any other wettability altering agent in an oil-rich porous medium is modeled by a network model of disordered pores transporting two immiscible fluids. We introduce a dynamic wettability altering mechanism, where the time dependent wetting property of each pore is determined by the cumulative flow of water through it. Simul… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1507.06198v1-abstract-full').style.display = 'inline'; document.getElementById('1507.06198v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1507.06198v1-abstract-full" style="display: none;"> The change in contact angles due to the injection of low salinity water or any other wettability altering agent in an oil-rich porous medium is modeled by a network model of disordered pores transporting two immiscible fluids. We introduce a dynamic wettability altering mechanism, where the time dependent wetting property of each pore is determined by the cumulative flow of water through it. Simulations are performed to reach steady-state for different possible alterations in the wetting angle ($胃$). We find that deviation from oil-wet conditions re-mobilizes the stuck clusters and increases the oil fractional flow. However, the rate of increase in the fractional flow depends strongly on $胃$ and as $胃\to 90^\circ$, a critical angle, the system shows critical slowing down which is characterized by two dynamic critical exponents. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1507.06198v1-abstract-full').style.display = 'none'; document.getElementById('1507.06198v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 July, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1406.4461">arXiv:1406.4461</a> <span> [<a href="https://arxiv.org/pdf/1406.4461">pdf</a>, <a href="https://arxiv.org/ps/1406.4461">ps</a>, <a href="https://arxiv.org/format/1406.4461">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1364/OL.39.004271">10.1364/OL.39.004271 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Raman Waveplate for Spinor BECs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Schultz%2C+J+T">Justin T. Schultz</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Azure Hansen</a>, <a href="/search/physics?searchtype=author&query=Bigelow%2C+N+P">Nicholas P. Bigelow</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1406.4461v1-abstract-short" style="display: inline;"> We demonstrate a waveplate for a pseudo-spin-1/2 Bose-Einstein condensate using a two-photon Raman interaction. The angle of the waveplate is set by the relative phase of the optical fields, and the retardance is controlled by the pulse area. The waveplate allows us to image maps of the Stokes parameters of a Bose-Einstein condensate and thereby measure its relative ground state phase. We demonstr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1406.4461v1-abstract-full').style.display = 'inline'; document.getElementById('1406.4461v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1406.4461v1-abstract-full" style="display: none;"> We demonstrate a waveplate for a pseudo-spin-1/2 Bose-Einstein condensate using a two-photon Raman interaction. The angle of the waveplate is set by the relative phase of the optical fields, and the retardance is controlled by the pulse area. The waveplate allows us to image maps of the Stokes parameters of a Bose-Einstein condensate and thereby measure its relative ground state phase. We demonstrate the waveplate by measuring the Stokes parameters of a coreless vortex. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1406.4461v1-abstract-full').style.display = 'none'; document.getElementById('1406.4461v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 June, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">4 pages, 3 figures, to appear in Optics Letters</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Optics Letters, Vol. 39, Issue 14, pp. 4271-4273 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1402.6384">arXiv:1402.6384</a> <span> [<a href="https://arxiv.org/pdf/1402.6384">pdf</a>, <a href="https://arxiv.org/format/1402.6384">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/9/07/C07019">10.1088/1748-0221/9/07/C07019 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Testbeam and Laboratory Characterization of CMS 3D Pixel Sensors </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Bubna%2C+M">M. Bubna</a>, <a href="/search/physics?searchtype=author&query=Alagoz%2C+E">E. Alagoz</a>, <a href="/search/physics?searchtype=author&query=Krzywda%2C+A">A. Krzywda</a>, <a href="/search/physics?searchtype=author&query=Koybasi%2C+O">O. Koybasi</a>, <a href="/search/physics?searchtype=author&query=Arndt%2C+K">K. Arndt</a>, <a href="/search/physics?searchtype=author&query=Bortoletto%2C+D">D. Bortoletto</a>, <a href="/search/physics?searchtype=author&query=Shipsey%2C+I">I. Shipsey</a>, <a href="/search/physics?searchtype=author&query=Bolla%2C+G">G. Bolla</a>, <a href="/search/physics?searchtype=author&query=Kok%2C+A">A. Kok</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+T+-">T. -E. Hansen</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+T+A">T. A. Hansen</a>, <a href="/search/physics?searchtype=author&query=Jensen%2C+G+U">G. U. Jensen</a>, <a href="/search/physics?searchtype=author&query=Brom%2C+J+M">J. M. Brom</a>, <a href="/search/physics?searchtype=author&query=Boscardin%2C+M">M. Boscardin</a>, <a href="/search/physics?searchtype=author&query=Chramowicz%2C+J">J. Chramowicz</a>, <a href="/search/physics?searchtype=author&query=Cumalat%2C+J">J. Cumalat</a>, <a href="/search/physics?searchtype=author&query=Betta%2C+G+F+D">G. F. Dalla Betta</a>, <a href="/search/physics?searchtype=author&query=Dinardo%2C+M">M. Dinardo</a>, <a href="/search/physics?searchtype=author&query=Godshalk%2C+A">A. Godshalk</a>, <a href="/search/physics?searchtype=author&query=Jones%2C+M">M. Jones</a>, <a href="/search/physics?searchtype=author&query=Krohn%2C+M+D">M. D. Krohn</a>, <a href="/search/physics?searchtype=author&query=Kumar%2C+A">A. Kumar</a>, <a href="/search/physics?searchtype=author&query=Lei%2C+C+M">C. M. Lei</a>, <a href="/search/physics?searchtype=author&query=Moroni%2C+L">L. Moroni</a>, <a href="/search/physics?searchtype=author&query=Perera%2C+L">L. Perera</a> , et al. (10 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1402.6384v2-abstract-short" style="display: inline;"> The pixel detector is the innermost tracking device in CMS, reconstructing interaction vertices and charged particle trajectories. The sensors located in the innermost layers of the pixel detector must be upgraded for the ten-fold increase in luminosity expected with the High- Luminosity LHC (HL-LHC) phase. As a possible replacement for planar sensors, 3D silicon technology is under consideration… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1402.6384v2-abstract-full').style.display = 'inline'; document.getElementById('1402.6384v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1402.6384v2-abstract-full" style="display: none;"> The pixel detector is the innermost tracking device in CMS, reconstructing interaction vertices and charged particle trajectories. The sensors located in the innermost layers of the pixel detector must be upgraded for the ten-fold increase in luminosity expected with the High- Luminosity LHC (HL-LHC) phase. As a possible replacement for planar sensors, 3D silicon technology is under consideration due to its good performance after high radiation fluence. In this paper, we report on pre- and post- irradiation measurements for CMS 3D pixel sensors with different electrode configurations. The effects of irradiation on electrical properties, charge collection efficiency, and position resolution of 3D sensors are discussed. Measurements of various test structures for monitoring the fabrication process and studying the bulk and surface properties, such as MOS capacitors, planar and gate-controlled diodes are also presented. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1402.6384v2-abstract-full').style.display = 'none'; document.getElementById('1402.6384v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 April, 2014; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 February, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1309.7926">arXiv:1309.7926</a> <span> [<a href="https://arxiv.org/pdf/1309.7926">pdf</a>, <a href="https://arxiv.org/ps/1309.7926">ps</a>, <a href="https://arxiv.org/format/1309.7926">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.112.033201">10.1103/PhysRevLett.112.033201 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ultracold Heteronuclear Mixture of Ground and Excited State Atoms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Khramov%2C+A">Alexander Khramov</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Anders Hansen</a>, <a href="/search/physics?searchtype=author&query=Dowd%2C+W">William Dowd</a>, <a href="/search/physics?searchtype=author&query=Roy%2C+R+J">Richard J. Roy</a>, <a href="/search/physics?searchtype=author&query=Makrides%2C+C">Constantinos Makrides</a>, <a href="/search/physics?searchtype=author&query=Petrov%2C+A">Alexander Petrov</a>, <a href="/search/physics?searchtype=author&query=Kotochigova%2C+S">Svetlana Kotochigova</a>, <a href="/search/physics?searchtype=author&query=Gupta%2C+S">Subhadeep Gupta</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1309.7926v3-abstract-short" style="display: inline;"> We report on the realization of an ultracold mixture of lithium atoms in the ground state and ytterbium atoms in the excited metastable 3P2 state. Such a mixture can support broad magnetic Feshbach resonances which may be utilized for the production of ultracold molecules with an electronic spin degree of freedom, as well as novel Efimov trimers. We investigate the interaction properties of the mi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1309.7926v3-abstract-full').style.display = 'inline'; document.getElementById('1309.7926v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1309.7926v3-abstract-full" style="display: none;"> We report on the realization of an ultracold mixture of lithium atoms in the ground state and ytterbium atoms in the excited metastable 3P2 state. Such a mixture can support broad magnetic Feshbach resonances which may be utilized for the production of ultracold molecules with an electronic spin degree of freedom, as well as novel Efimov trimers. We investigate the interaction properties of the mixture in the presence of an external magnetic field and find an upper limit for the background interspecies two-body inelastic decay coefficient of K'2 < 3e-12 cm^3/s for the 3P2 m_J=-1 substate. We calculate the dynamic polarizabilities of the Yb 3P2 magnetic substates for a range of wavelengths, and find good agreement with our measurements at 1064nm. Our calculations also allow the identification of magic frequencies where Yb ground and metastable states are identically trapped and the determination of the interspecies van der Waals coefficients. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1309.7926v3-abstract-full').style.display = 'none'; document.getElementById('1309.7926v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 February, 2014; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 September, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 4 figures, supplemental material</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 112, 033201 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1308.5800">arXiv:1308.5800</a> <span> [<a href="https://arxiv.org/pdf/1308.5800">pdf</a>, <a href="https://arxiv.org/ps/1308.5800">ps</a>, <a href="https://arxiv.org/format/1308.5800">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-ph</span> </div> </div> <p class="title is-5 mathjax"> Local dynamics of a randomly pinned crack front: A numerical study </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Gjerden%2C+K+S">Knut Skogstrand Gjerden</a>, <a href="/search/physics?searchtype=author&query=Stormo%2C+A">Arne Stormo</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A">Alex Hansen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1308.5800v1-abstract-short" style="display: inline;"> We investigate numerically the dynamics of crack propagation along a weak plane using a model consisting of fibers connecting a soft and a hard clamp. This bottom-up model has previously been shown to contain the competition of two crack propagation mechanisms: coalescence of damage with the front on small scales and pinned elastic line motion on large scales. We investigate the dynamical scaling… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1308.5800v1-abstract-full').style.display = 'inline'; document.getElementById('1308.5800v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1308.5800v1-abstract-full" style="display: none;"> We investigate numerically the dynamics of crack propagation along a weak plane using a model consisting of fibers connecting a soft and a hard clamp. This bottom-up model has previously been shown to contain the competition of two crack propagation mechanisms: coalescence of damage with the front on small scales and pinned elastic line motion on large scales. We investigate the dynamical scaling properties of the model, both on small and large scale. The model results compare favorable with experimental results. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1308.5800v1-abstract-full').style.display = 'none'; document.getElementById('1308.5800v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 August, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2013. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1305.4087">arXiv:1305.4087</a> <span> [<a href="https://arxiv.org/pdf/1305.4087">pdf</a>, <a href="https://arxiv.org/format/1305.4087">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.111.053002">10.1103/PhysRevLett.111.053002 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Decay rate measurement of the first vibrationally excited state of MgH$^+$ in a cryogenic Paul trap </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/physics?searchtype=author&query=Versolato%2C+O+O">O. O. Versolato</a>, <a href="/search/physics?searchtype=author&query=Schwarz%2C+M">M. Schwarz</a>, <a href="/search/physics?searchtype=author&query=Hansen%2C+A+K">A. K. Hansen</a>, <a href="/search/physics?searchtype=author&query=Gingell%2C+A+D">A. D. Gingell</a>, <a href="/search/physics?searchtype=author&query=Windberger%2C+A">A. Windberger</a>, <a href="/search/physics?searchtype=author&query=K%C5%82osowski%2C+%C5%81">艁. K艂osowski</a>, <a href="/search/physics?searchtype=author&query=Ullrich%2C+J">J. Ullrich</a>, <a href="/search/physics?searchtype=author&query=Jensen%2C+F">F. Jensen</a>, <a href="/search/physics?searchtype=author&query=L%C3%B3pez-Urrutia%2C+J+R+C">J. R. Crespo L贸pez-Urrutia</a>, <a href="/search/physics?searchtype=author&query=Drewsen%2C+M">M. Drewsen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1305.4087v1-abstract-short" style="display: inline;"> We present a method to measure the decay rate of the first excited vibrational state of simple polar molecular ions being part of a Coulomb crystal in a cryogenic linear Paul trap. Specifically, we have monitored the decay of the $|谓$=$1,J$=$1 \rangle_X$ towards the $|谓$=$0,J$=$0 \rangle_X$ level in MgH$^+$ by saturated laser excitation of the $|谓$=$0,J$=$2 \rangle_X$-$|谓$=$1,J$=$1 \rangle_X$ tran… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1305.4087v1-abstract-full').style.display = 'inline'; document.getElementById('1305.4087v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1305.4087v1-abstract-full" style="display: none;"> We present a method to measure the decay rate of the first excited vibrational state of simple polar molecular ions being part of a Coulomb crystal in a cryogenic linear Paul trap. Specifically, we have monitored the decay of the $|谓$=$1,J$=$1 \rangle_X$ towards the $|谓$=$0,J$=$0 \rangle_X$ level in MgH$^+$ by saturated laser excitation of the $|谓$=$0,J$=$2 \rangle_X$-$|谓$=$1,J$=$1 \rangle_X$ transition followed by state selective resonance enhanced two-photon dissociation out of the $|谓$=$0,J$=$2 \rangle_X$ level. The technique enables the determination of decay rates, and thus absorption strengths, with an accuracy at the few percent level. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1305.4087v1-abstract-full').style.display = 'none'; document.getElementById('1305.4087v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 May, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 4 figures</span> </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a 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