Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session R15: Granular, Porous Media, & Multiphase Flows I |
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Sponsoring Units: DFD GSNP Chair: Anthony Chieco, University of Pennsylvania Room: 210/212 |
Thursday, March 5, 2020 8:00AM - 8:36AM |
R15.00001: Flow of emulsions in heterogeneous media Marine LE BLAY, Denis Bartolo We elucidate the collective dynamics of particles hydrodynamically driven through disordered environments. We build on model microfluidic experiments where we track the individual dynamics of hundreds of thousands oil droplets advected by an aqueous fluid through random lattices of pinning sites. Increasing the driving flow, we identify a sharp transition between a creeping regime and a mobilization regime where a finite fraction of the droplets proceed through a sparse network of branched and reconnected rivers. This dynamical transition is a critical phenomenon characterised by diverging time and length scales at the onset of mobilization. |
Thursday, March 5, 2020 8:36AM - 8:48AM |
R15.00002: Controlling capillary fingering using pore size gradients in disordered media Nancy Lu, Christopher Browne, Daniel Amchin, Janine K Nunes, Sujit Datta Capillary fingering is a displacement process that can occur when a non-wetting fluid displaces a wetting fluid from a homogeneous disordered porous medium. Here, we investigate how this process is influenced by a pore size gradient. Using microfluidic experiments and computational pore-network models, we show that the non-wetting fluid displacement behavior depends sensitively on the direction and the magnitude of the gradient. The fluid displacement depends on the competition between a pore size gradient and pore-scale disorder; indeed, a sufficiently large gradient can completely suppress capillary fingering. By analyzing capillary forces at the pore scale, we identify a non-dimensional parameter that describes the physics underlying these diverse flow behaviors. Our results thus expand the understanding of flow in complex porous media and suggest a new way to control flow behavior via the introduction of pore size gradients. |
Thursday, March 5, 2020 8:48AM - 9:00AM |
R15.00003: Fluid Flow Mechanisms in Shale Organic Nanopores Felipe Perez Valencia, Deepak Devegowda From a fluid dynamics perspective, production of hydrocarbons from unconventional reservoirs represents a challenge because (1) the fluids are located in porous organic matter in shale rocks where the pore sizes range from a few to a couple hundred nanometers, (2) the permeability of shale rocks is on the order of nanodarcy (1 darcy ≈ 10−12 m2), and (3) the behavior of the fluids and their interactions with the pore surface are poorly understood. In this work we use molecular dynamics simulations to create molecular models of organic matter (kerogen) that host a hydrocarbon mixture that is liquid at normal conditions of pressure and temperature. Our models account for the chemical functionality and pore geometry of kerogen and serve as rigid frameworks to study the mechanisms by which the different species of the mixture flow from organic pores to a microfracture. |
Thursday, March 5, 2020 9:00AM - 9:12AM |
R15.00004: Colloidal transport in porous media: Pore-scale interplay of advection, deposition, and erosion Navid Bizmark, Joanna Schneider, Rodney Priestley, Sujit Datta There is significant interest in applying colloids to remediate contaminated soils or aquifers. However, the transport of such colloids to porous subsurface regions is complex due to the interplay of particle adsorption, surface erosion, and pore-space advection. Here, we use a transparent model porous medium to directly image in 3D the interplay between adsorption and erosion events at the pore scale. Analysis of these processes allows us to determine the net particle deposition rate and further to predict the macroscopic net particle deposition profile. These findings show how the pore-scale dynamics can be controlled for macroscopic aims in remediation practices. |
Thursday, March 5, 2020 9:12AM - 9:24AM |
R15.00005: CFD-DEM Study of Anomalous Collapse of Interacting Bubbles into an Incipiently Fluidized Bed Azin Padash, Christopher M Boyce Computational fluid dynamics – discrete element method (CFD-DEM) recreates the collapse phenomenon of the recent magnetic resonance imaging (MRI) study (Boyce et al., Phys. Rev. Fluids, 2019, 034303) in which one bubble collapses when two bubbles are injected side-by-side into an incipiently fluidized bed, and the other bubble does not collapse and reaches the surface of the bed. Our simulation results reveal the underlying physics behind the collapse phenomenon which was ambiguous in the 2D imaging plane of the experimental results. The 3D visualization of voidage field and gas velocity field from simulations demonstrates that bubble collapses and it does not move out of the imaging plane of the study. Also, our results confirm the hypothesis of the MRI study where there should be a slight difference in size of the bubbles, which causes the gas flow to channel more favorably to the larger bubble. Therefore, the smaller bubble does not receive enough gas flow to channel through it and support its roof which leads to its collapse. |
Thursday, March 5, 2020 9:24AM - 9:36AM |
R15.00006: Colloid-Enhanced Mobilization of Immiscible Fluids in Porous Media Joanna Schneider, Navid Bizmark, Rodney Priestley, Sujit Datta More than 50% of the United States receives its drinking water from porous groundwater aquifers that are susceptible to contamination from industrial processes. The persistence of these contaminants after their initial introduction requires specialized remediation techniques. Here, we show that injection of colloidal particles improves contaminant removal from a porous medium compared to ambient flow alone. Specifically, by tailoring colloidal properties and injection conditions, we find that particles deposit on the solid surfaces of the porous medium, enhancing the local fluid pressure and pushing out trapped non-aqueous contaminants. We also develop a model to describe how changing permeability impacts mobilization and compare the model’s predictions to experimental results. Importantly, this approach avoids the need for repeated pumping and treatment, representing a major advancement in simplicity and cost over current approaches. |
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R15.00007: Complex Conductivity in Saturated Porous Media: Role of Membrane Polarization Qiuzi Li, Lang Feng, Steve Cameron, Harry Deckman, Deniz Ertas We quantitatively explain the origin of complex conductivity of a porous medium made of non-conductive grains, saturated with a binary electrolyte. The medium is assumed to possess a heterogeneous immobile charge density, and to interact with ions in the electrolyte only through electrostatic interactions. We establish a theoretical framework relating spectral complex conductivity in these systems to the geometry and intrinsic properties of the materials, and validate the results with experiments on model systems. We conclude that complex conductivity arises due to concentration (membrane) polarization, which is driven by spatial inhomogeneity in the ionic transferences, i. e., the proportion of current carried by the cation vs. the anion. We obtain quantitative agreement between experiment and theory, not just for characteristic frequencies and amplitudes, but for the entire spectral shape of the phase angle between electric field and current density. The amplitude, scaling of the characteristic frequency with feature size, and the spectral shape of the phase angle differ markedly from complex conductivity associated with dispersed electronic conductors. |
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