The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
David A Weitz - One of the best experts on this subject based on the ideXlab platform.
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spatial fluctuations of Fluid velocities in flow through a three dimensional porous medium
Physical Review Letters, 2013Co-Authors: Sujit S Datta, Harry Chiang, T S Ramakrishnan, David A WeitzAbstract:: We use confocal microscopy to directly visualize the spatial fluctuations in Fluid flow through a three-dimensional porous medium. We find that the velocity magnitudes and the velocity components both along and transverse to the imposed flow direction are exponentially distributed, even with residual trapping of a second Immiscible Fluid. Moreover, we find pore-scale correlations in the flow that are determined by the geometry of the medium. Our results suggest that despite the considerable complexity of the pore space, Fluid flow through it is not completely random.
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Janus particles templated from double emulsion droplets generated using microFluidics
Langmuir, 2009Co-Authors: Chia-hung Chen, Rhutesh K. Shah, Adam R. Abate, David A WeitzAbstract:We present a simple microFluidics-based technique to fabricate Janus particles using double-emulsion droplets as templates. Since each half of the particles is templated from a different Immiscible Fluid, this method enables the formation of particles from two materials with vastly different properties. The use of microFluidics affords excellent control over the size, morphology, and monodispersity of the particles.
Adrian Sheppard - One of the best experts on this subject based on the ideXlab platform.
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x ray imaging and analysis techniques for quantifying pore scale structure and processes in subsurface porous medium systems
Advances in Water Resources, 2013Co-Authors: Dorthe Wildenschild, Adrian SheppardAbstract:We report here on recent developments and advances in pore-scale X-ray tomographic imaging of subsurface porous media. Our particular focus is on Immiscible multi-phase Fluid flow, i.e., the displacement of one Immiscible Fluid by another inside a porous material, which is of central importance to many natural and engineered processes. Multiphase flow and displacement can pose a rather difficult problem, both because the underlying physics is complex, and also because standard laboratory investigation reveals little about the mechanisms that control micro-scale processes. X-ray microtomographic imaging is a non-destructive technique for quantifying these processes in three dimensions within individual pores, and as we report here, with rapidly increasing spatial and temporal resolution.
Alex Hansen - One of the best experts on this subject based on the ideXlab platform.
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A new set of equations describing Immiscible two-phase flow in homogeneous porous media
arXiv: Fluid Dynamics, 2016Co-Authors: Alex Hansen, Santanu Sinha, Isha Savani, Dick Bedeaux, Signe Kjelstrup, Morten VassvikAbstract:Based on a simple scaling assumption concerning the total flow rate of Immiscible two-phase flow in a homogeneous porous medium under steady-state conditions and a constant pressure drop, we derive two new equations that relate the total flow rate to the flow rates of each Immiscible Fluid. By integrating these equations, we present two integrals giving the flow rate of each Fluid in terms of the the total flow rate. If we in addition assume that the flow obeys the relative permeability (generalized Darcy) equations, we find direct expressions for the two relative permeabilities and the capillary pressure in terms of the total flow rate. Hence, only the total flow rate as a function of saturation at constant pressure drop across the porous medium needs to be measured in order to obtain all three quantities. We test the equations on numerical and experimental systems.
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capillary driven instability of Immiscible Fluid interfaces flowing in parallel in porous media
Physical Review E, 2008Co-Authors: Thomas Ramstad, Alex HansenAbstract:When Immiscible wetting and nonwetting Fluids move in parallel in a porous medium, an instability may occur at sufficiently high capillary numbers so that interfaces between the Fluids initially held in place by the porous medium are mobilized. A boundary zone containing bubbles of both Fluids evolves, which has a well-defined thickness. This zone moves at constant average speed toward the nonwetting Fluid. A diffusive current of bubbles of nonwetting Fluid into the wetting Fluid is set up.
Ran Holtzman - One of the best experts on this subject based on the ideXlab platform.
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Immiscible Fluid displacement in porous media with spatially correlated particle sizes
Advances in Water Resources, 2019Co-Authors: Oshri Borgman, Thomas Darwent, Enrico Segre, Lucas Goehring, Ran HoltzmanAbstract:Immiscible Fluid displacement in porous media is fundamental for many environmental processes, including infiltration of water in soils, groundwater remediation, enhanced recovery of hydrocarbons and CO2 geosequestration. Microstructural heterogeneity, in particular of particle sizes, can significantly impact Immiscible displacement. For instance, it may lead to unstable flow and preferential displacement patterns. We present a systematic, quantitative pore-scale study of the impact of spatial correlations in particle sizes on the drainage of a partially-wetting Fluid. We perform pore-network simulations with varying flow rates and different degrees of spatial correlation, complemented with microFluidic experiments. Simulated and experimental displacement patterns show that spatial correlation leads to more preferential invasion, with reduced trapping of the defending Fluid, especially at low flow rates. Numerically, we find that increasing the correlation length reduces the Fluid-Fluid interfacial area and the trapping of the defending Fluid, and increases the invasion pattern asymmetry and selectivity. Our experiments, conducted for low capillary numbers, support these findings. Our results delineate the significant effect of spatial correlations on Fluid displacement in porous media, of relevance to a wide range of natural and engineered processes.
Dorthe Wildenschild - One of the best experts on this subject based on the ideXlab platform.
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x ray imaging and analysis techniques for quantifying pore scale structure and processes in subsurface porous medium systems
Advances in Water Resources, 2013Co-Authors: Dorthe Wildenschild, Adrian SheppardAbstract:We report here on recent developments and advances in pore-scale X-ray tomographic imaging of subsurface porous media. Our particular focus is on Immiscible multi-phase Fluid flow, i.e., the displacement of one Immiscible Fluid by another inside a porous material, which is of central importance to many natural and engineered processes. Multiphase flow and displacement can pose a rather difficult problem, both because the underlying physics is complex, and also because standard laboratory investigation reveals little about the mechanisms that control micro-scale processes. X-ray microtomographic imaging is a non-destructive technique for quantifying these processes in three dimensions within individual pores, and as we report here, with rapidly increasing spatial and temporal resolution.
