Bulletin of the American Physical Society
73rd Annual Meeting of the APS Division of Fluid Dynamics
Volume 65, Number 13
Sunday–Tuesday, November 22–24, 2020; Virtual, CT (Chicago time)
Session U12: Microscale Flows: Porous Media and Porous Electrodes (8:45am - 9:30am CST)Interactive On Demand
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U12.00001: Random Emulation of Large-Scale Natural Pore Networks Daniel Meyer Over the past years, tomographic scanning techniques like micro-CT have become popular for the acquisition of high-fidelity void-space geometries of natural porous media [e.g., Raeini, Bijeljic, and Blunt, Physical Review E, 96, 1 (2017)]. Limitations both in computing time and memory prohibit, however, direct numerical simulation (DNS) of flow and transport in large resp. detailed sample geometries. Pore networks derived from scans alleviate this limitation, but still necessitate a methodology to extrapolate to larger samples. In this work, we present a new pore network generation algorithm. While emulating from an existing base network new networks of equal or larger sizes, the new algorithm scales approximately linearly with the pore count and maintains (1) pore coordination-number statistics, (2) geometrical pore/throat properties, as well as (3) the potentially inhomogeneous spatial clustering of pores. While existing methods address the first two properties [e.g., Idowu, Pore-Scale Modeling: Stochastic Network Generator and Modeling of Rate Effects in Waterflooding, Imperial College London (2009)], the third point is crucial to match flow/transport properties such as the permeability in inhomogeneous media. [Preview Abstract] |
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U12.00002: Pore-scale Observations of Salt Precipitation using Microfluidics Tsai-Hsing Ho, Peichun Amy Tsai This study is motivated by the challenging needs for unraveling the pore-scale dynamics and under-lying mechanisms of salt precipitation, a potential threat that hinders the processes of Carbon Capture and Storage (CCS) in deep saline aquifers. We experimentally investigate the influences of pore-structure and brine concentration on the drying rate of brine and subsequent salt precipitation using microfluidics. Three distinct precipitation stages are observed: (I) initial, (II) rapid growth, and (II) final phases, corresponding to the changing brine drying rate respectively. Considerable local salt precipitation formed in the rapid-growth period connects with large pools of residual brine, providing ion source for extended salt nucleation. In addition, the salt-precipitation speeds during the second phase are linearly dependent on the brine-drying rate. These result would help estimate the total amount and the spreading rate of salt precipitation for different brine-drying rates. [Preview Abstract] |
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U12.00003: Computational modeling of polydisperse carbon particles in electrochemical flow capacitors Brandon Stacks, Haoxiang Luo, Deyu Li, Kelsey Hatzell Electrochemical flow capacitors (EFCs) are a promising new type of energy storage device due to high storage capacity, low fatigue rates, and high discharge rates. These devices employ the electric double layer of charged active carbon particles in a flowable slurry, i.e., a `flowable electrode', to store ionic charges from an electrolyte solution. The objective of this study is to build upon previous simulations in our lab that studied the hydrodynamic and electrical interactions of the carbon particles in the flowing slurry. A Stokesian dynamics approach is used to simulate motion of the particles near a no-slip wall that acts as the stationary electrode, while also solving a generalized electrical circuit for charge transfer among the particles. In the present study, we focus on the effect of the smaller carbon black particles, which are commonly included in the slurry to increase particle-particle interactions, cluster formation, and charge percolation. The inclusion of these smaller particles (simulated as 5 times smaller in radius) necessitates an extension of the parameter values used in previous simulations. In this talk, we will discuss the modeling approach as well as the simulation results. [Preview Abstract] |
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U12.00004: Drag force exerted on a confined porous aggregate Guillaume Grosjean, Alban Sauret Cohesive particles flowing in tubings and microfluidic channels sometimes lead to the growth of aggregates of sizes comparable to the dimension of the channel. In this situation, the viscous force exerted on the aggregate is influenced both by the confinement and the permeability of the aggregate. In particular, for sufficiently large permeabilities, the drag force decreases significantly. We numerically consider the drag force exerted on a porous particle in a cylindrical tube and in a rectangular microchannel at small Reynolds number to determine how the combination of the confinement and the permeability modifies the drag of the aggregate. The Navier-Stokes equations for the fluid are coupled with the Darcy-Brinkman equations in the porous aggregate. We determine the drag force as a function of the Reynolds number, the confinement ratio, and the permeability of the aggregate. Using these numerical results, we provide empirical expressions of the evolution of the drag. The strong decrease of the drag force induced by the permeability and the confinement has important implications on the ability to transport and unclog a porous aggregate in a microchannel. [Preview Abstract] |
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U12.00005: Flow Driven Transport of Soft Particles in Porous Media Shuaijun Li, Honghui Yu, Jing Fan Flow driven transport of soft particles in porous media occurs in many natural and engineering processes. For example, in preformed-particle-gel (PPG) treatment in oil recovery, microgels are injected into reservoirs for improved conformance. While the measurable properties in this process are at microscale, such as gel size, stiffness, and pore flow velocity, the macroscopic permeability directly correlates to the overall recovery efficiency. Therefore, it is desirable to find the quantitative relation between the macroscopic permeability and the relevant microscopic properties. In this work, we address this issue by equating total energy consumption with the sum of energy dissipation in the system. The viscous dissipation is obtained from Darcy's law. The frictional loss is determined by multiplying scaled gel sliding distance and the force exerted on one gel blocking a pore, which was derived in our previous study. We then obtain a differential equation with respect to pressure. The solution of the differential equation gives a quantitative relation between the total pressure drop and pore-scale properties. The work improves our understanding on transport of soft particles in porous media and directly benefits the relevant industrial applications. [Preview Abstract] |
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