Bulletin of the American Physical Society
61st Annual Meeting of the APS Division of Fluid Dynamics
Volume 53, Number 15
Sunday–Tuesday, November 23–25, 2008; San Antonio, Texas
Session ME: Porous Media I |
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Chair: John Hinch, DAMTP, Cambridge University Room: 003A |
Tuesday, November 25, 2008 8:00AM - 8:13AM |
ME.00001: Three-dimensional micro-scale flow simulation and colloid transport modeling in saturated soil porous media Charmaine Qiu, Hui Gao, Dimin Fan, Yan Jin, Lian-Ping Wang Adequate understanding of the mechanism of colloid retention by soil porous media is essential to the prediction and monitoring of the transport of contaminants by groundwater in the subsurface environment. Preliminary studies reveal that pore-scale processes are governed by colloid-grain and colloid-colloid interactions. In this talk, we focus on the assessment of their effects using a computational approach. First, micro-scale viscous flow in a model porous medium, i.e., a square channel filled with spherical grains, is simulated by simultaneously applying a mesoscopic lattice Boltzmann equation and a Navier-Stokes based hybrid approach, for rigorous cross-validation of the simulated flow. Lagrangian tacking of individual colloids is then conducted by solving colloids equation of motion including local hydrodynamic effects and physicochemical forces. Analysis of colloid transport will encompass effects of flow straining, depth-dependent spatial distribution, and retention of colloids under different solution ionic strengths, flow speeds, and packing configurations. Comparison with parallel experimental results using confocal microscopy will be briefly discussed. [Preview Abstract] |
Tuesday, November 25, 2008 8:13AM - 8:26AM |
ME.00002: Numerical simulation of micro-scale flow and colloid transport near air-water interface in unsaturated porous media Grace Shi, Volha Lazouskaya, Yan Jin, Lian-Ping Wang This work is motivated by the need to understand colloid-facilitated transport of contaminants in unsaturated soil porous media. Unsaturated soil is characterized by the presence of moving air-water interface within micro-scale flow passage of soil porous media. Previous experimental observations using confocal microscopy reveal the importance of air-water interface and contact line on the retention of colloids. Here we develop a computational approach to model the transport and retention of colloids near the interfacial region. First, we simulate the microscale flow field near the interfacial region by simultaneously employing a mesoscopic lattice Boltzmann equation approach and a macroscopic volume-of-fluid approach. We will examine how the flow field changes with capillary number, Reynolds number, density ratio, and viscosity ratio. Numerical issues such as stability and spurious currents for interfacial flow simulation will be discussed. We then track the motion of colloids by solving colloids equation of motion including hydrodynamic forces and physicochemical forces, to study the trajectories of colloids and the likely retention sites. Numerical results will be compared with parallel visualization experiments. [Preview Abstract] |
Tuesday, November 25, 2008 8:26AM - 8:39AM |
ME.00003: High performance 3D simulation of reactive transport in porous media using level set method Xiaoyi Li, Hai Huang, Paul Meakin The coupled processes of fluid flow, solute transport and mineral precipitation/dissolution in porous media are of great interest in a large variety of scientific and engineering areas. In this work, a high performance parallel simulator using MPI is developed to simulate pore-scale coupled reactive fluid flow and structure evolutions in porous media with complex and realistic pore geometries. Convection, diffusion, and chemical reaction resulting in geometrical changes in the pore spaces are treated simultaneously. The reaction-induced evolution of solid grain surface is captured using a level set method. A more elegant sub-grid representation of the interface is obtained by using the level set approach, instead of the pixel-based representation of the interface used in most lattice-Boltzmann and cellular-automata methods. The performance scaling of the method is demonstrated. The precipitation in a 3D random porous medium represented by packed solid spheres is simulated and discussed. More realistic relationships between permeability and porosity of the porous media are obtained from simulation. The simulation can provide a physics-based permeability-porosity model for continuum-scale reactive transport simulations. [Preview Abstract] |
Tuesday, November 25, 2008 8:39AM - 8:52AM |
ME.00004: Capillary Force Driven Spread of Wetting Liquid into Porous Medium B. Markicevic, H. Li, A.R. Zand, H.K. Navaz Once deposited onto porous medium surface, a wetting liquid imbibes porous medium due to influence of the capillary pressure. While there is free liquid on the porous medium surface, the liquid primary spread into porous medium is driven by difference in the capillary pressures in the free liquid and the liquid in porous medium. Having the free liquid volume equal to zero, the spread continues as secondary spread due to the local porous medium heterogeneities that cause the gradients in the capillary pressure and liquid saturation. A \textit{uni}-directional primary and secondary spreads in the rectangular domain are studied experimentally, where the saturation profiles along principal flow direction are experimentally measured for different times throughout the liquid spread. For medium grain sand/ ethylene glycol it was found that the wetted volume increases almost twice after the time equal to fourteen days. For the same \textit{uni}-directional flow, the axial direction saturation profiles are also predicted numerically and compared with the experimental saturation profiles. The numerical solution is obtained using the capillary network model that utilizes the micro-force balance at the liquid free interface, and the network parameters are varied until matching the experimental and numerical saturation profiles. Finally, from the capillary network defined the capillary pressure and the relative permeability curves are determined. [Preview Abstract] |
Tuesday, November 25, 2008 8:52AM - 9:05AM |
ME.00005: Flow in heterogeneous media and autocatalytic reaction using lattice BGK simulations Nolwenn Jarrige, J\'er\^ome Martin, Nicole Rakotomalala, Dominique Salin, Laurent Talon Autocatalytic reaction front between two reacting species is able to propagate as a solitary wave that is at constant velocity and with a stationary concentration profile resulting from a balance between molecular diffusion and chemical reaction. In the presence of a hydrodynamic flow, the wave moves with a higher velocity. Indeed, as in Taylor's dispersion, the flow velocity field increases the dispersion across the chemical front and therefore the front velocity. Using lattice BGK simulations, we use this property to deduce some characteristics of a heterogeneous medium. The medium consists of a two dimensional heterogeneous fracture, the mean permeability, the heterogeneities and the correlation length of which are known. The flow through the fracture is solved using Darcy-Brinkman equation. The dispersion of heterogeneities involve heterogeneities in the hydrodynamic field. We study the influence of the flow field heterogeneities on the chemical velocity. We will discuss the relevance of the quantitative measurements to characterize the porous medium. [Preview Abstract] |
Tuesday, November 25, 2008 9:05AM - 9:18AM |
ME.00006: Capillary rise of a power law fluid into a deformable porous material Javed Siddique, Daniel Anderson We examine a mathematical model for capillary rise of a power law fluid into a one dimensional deformable porous material. We use mixture theory to formulate the model. Of interest are the interface positions of the solid and the liquid as the material deforms. If the effects of gravity are absent, the model admits a similarity solution, which we compute numerically. If the effects of gravity are included, the free boundary problem is solved numerically. In this case, steady state solutions exist and are the same for both Newtonian and non-Newtonian cases. For comparison, we also examine capillary rise into a rigid porous material, where liquid imbibition occurs without material deformation. In this talk we compare the Newtonian and non-Newtonian results in the absence and the presence of gravity effects for both rigid and deformable porous material. [Preview Abstract] |
Tuesday, November 25, 2008 9:18AM - 9:31AM |
ME.00007: Imbibition in layered systems of packed beads Laetitia Sangne, Mathilde Reyssat, Ernst Van Nierop, Howard A. Stone It is well known that during imbibition of uniform porous media, the penetration distance increases as the square root of time. However, this ``diffusive'' result is not observed when the spatial arrangement of the beads is not uniform. We investigate two specific cases of inhomogeneity: (i) a system made with two layers each of a uniform bead size, (ii) a gradient of permeability. In both cases, deviations from the ``diffusive'' dynamics are observed and explained theoretically. [Preview Abstract] |
Tuesday, November 25, 2008 9:31AM - 9:44AM |
ME.00008: Axisymmetric viscous gravity currents flowing over a deep porous medium Melissa J. Spannuth, Jerome A. Neufeld, J.S. Wettlaufer, M. Grae Worster When a viscous gravity current flows over a horizontal porous medium it not only spreads laterally, but also drains vertically into the substrate. Such flows occur in many environmental and industrial settings. We have studied the axisymmetric spreading of such currents over a deep porous medium fed by a point source of fluid at the origin. For constant fluid influx we observe the existence of a steady state in which drainage exactly balances external fluid input and the current ceases spreading. The steady state is well-described by the analytical solution of the equations for a viscous gravity current spreading due to the slope of its free surface augmented by a simple drainage law. In addition, scaling laws derived from the full governing equations collapse the experimental data and a numerical solution accurately predicts the evolution of the current. Finally, non-ideal behavior demonstrated by experiments using a more complex porous medium indicate the sensitive dependence of current behavior on the properties and geometry of the underlying porous medium. [Preview Abstract] |
Tuesday, November 25, 2008 9:44AM - 9:57AM |
ME.00009: Two-Phase Flow in Porous Media with Slip Boundary Condition S. Berg, A.W. Cense, J.P. Hofman, R.M.M. Smits 2-phase flow in porous media is typically described by Darcy's law extended with the concept of relative permeability, $k_{r}$, for the water and the oil phase. Using a single phase permeability of a wetting fluid (water) as reference, $kr $naturally assumes a maximum value of 0 $\le kr \le $ 1. Several reports in literature and our own experimental data show in some cases endpoint relative permeabilities of the non-wetting phase with 2 $< kr <$ 4. That means that in 2-phase flow in the porous medium, the flux of the non-wetting phase is higher when a small amount of the wetting phase is present. We explain this behavior by drawing an analogy between $kr $>1 and a \textit{slip-boundary condition} for the pore scale flow using a model description assuming flow in capillary tubes with a slip boundary condition. This model predicts that the flux increase due to slip depends on the equivalent capillary radius of the flow channels. Our $kr$ data specifically follows this dependence indicating that slip is a plausible explanation for the observation of $kr > $ 1. [Preview Abstract] |
Tuesday, November 25, 2008 9:57AM - 10:10AM |
ME.00010: Full-field Mean Velocity Measurements inside a Scaled Metal Foam Replica using Magnetic Resonance Velocimetry Andrew Onstad, Francisco Medina, Chris Elkins, Ryan Wicker, John Eaton Metal foams have gained interest in heat transfer applications due to their large convective surface area and high thermal conductivity. The flow passage through the foam is very complex suggesting the likelihood of high thermal transport coefficients. Furthermore, some thermal measurements indicate highly non-uniform flows in the foam interior. We examine the flow behavior inside the foam quantitatively using Magnetic Resonance Velocimetry (MRV). The technique is capable of measuring the three-component, mean velocity field within complex geometries without optical access or the use of flow tracers. To create the MR compatible replica, a 4 pore/cm aluminum foam specimen was imaged at a resolution of 36$\mu$m using an x-ray Computed Tomography (CT) scanner, scaled up by a factor of 4, then reconstructed in plastic by stereolithography (SLA). The spatially resolved, 3D mean velocity field was then measured by MRV where contrast enhanced water flowed through the foam replica at $Re_{Pore}=730$. [Preview Abstract] |
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