Bulletin of the American Physical Society
60th Annual Meeting of the Divison of Fluid Dynamics
Volume 52, Number 12
Sunday–Tuesday, November 18–20, 2007; Salt Lake City, Utah
Session AQ: Porous Media Flows I |
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Chair: Thomas Hauser, Utah State University Room: Salt Palace Convention Center 251 E |
Sunday, November 18, 2007 8:30AM - 8:43AM |
AQ.00001: Effects of heterogeneity on density-driven convection in porous media Saikiran Rapaka, Rajesh Pawar, Philip Stauffer, George Zyvoloski, Dongxiao Zhang, Shiyi Chen In the context of geological sequestration of carbon dioxide, it is well known that convective transport is expected to play a crucial role in accelerating the rate of carbon dioxide dissolution into the brine present in the aquifer. Most previous studies of this convective process have considered a homogeneous porous medium. However, the properties of the aquifer are known to be extremely heterogeneous over all length scales. Previous research on convection in heterogeneous media has suggested that global quantities like Rayleigh number etc. may be inadequate for describing convective transport in such systems. ~In this work, we consider the process of density-driven convection in heterogeneous porous media using detailed numerical simulations with a Monte-Carlo approach. We present results using an averaged global Rayleigh number and show that it can be extremely useful in predicting convective transport in heterogeneous media. We also discuss the role played by the properties of the medium heterogeneity, and analyze the uncertainty in the predictions as the variance of the permeability field is increased. [Preview Abstract] |
Sunday, November 18, 2007 8:43AM - 8:56AM |
AQ.00002: Gravity currents with residual trapping in confined, sloping aquifers Marc Hesse, Franklin Orr, Jr., Hamdi Tchelepi Motivated by geological CO$_2$ storage, we present a sharp-interface vertical equilibrium model for the migration of immiscible gravity currents with constant residual trapping in a two-dimensional, sloping, confined aquifer. The continuous trapping decreases the current volume until the current is exhausted. Analytic and semi-analytic solutions for the limiting hyperbolic problem are derived. Comparison with numerical solutions show that the limiting solutions are good approximation to the numerical solution for high mobility ratios, even for Peclet numbers of order unity. In these cases our analysis shows that the dimension less migration time and distance increase with increasing mobility ratio and decrease with increasing trapped saturation, but they are only a weak function of the slope as long as the slope is finite. In sloping aquifers the current evolution is divided into two stages: an initial stage of power-law decrease of volume - similar to horizontal aquifers - followed by a later stage of rapid volume reduction. Several large regional saline aquifers are gently sloping, but lack a structural closure. Our results suggest that the efficient residual trapping induced by slope of the aquifer may allow CO$_2$ storage. [Preview Abstract] |
Sunday, November 18, 2007 8:56AM - 9:09AM |
AQ.00003: Pumping unconfined aquifers near shallow streams Anthony Davis, Stefan Llewellyn Smith A well is inserted in a horizontally unbounded water table, with an impenetrable base, at a location removed from a shallow stream. The pressure head is initially zero but changes after constant pumping is begun. It is governed by a diffusion equation and subject to a free surface condition whose formulation invokes Darcy's Law. Fourier and Laplace transforms are used to solve for the pressure gradient, with particular focus on its far field and river surface values which measure from where the well water is drawn. The simpler steady solution gives a misleading guide to the flow development because of the significant asymmetry created by the well location which might be many river widths away from the river. [Preview Abstract] |
Sunday, November 18, 2007 9:09AM - 9:22AM |
AQ.00004: Two-phase flows of immiscible fluids in porous media Guillaume Degre, Mikael Herbert, Mikel Morvan, Mathieu Joanicot, Annie Colin This paper describes an experimental work on the study of two-phase flow in porous media. We investigate both drainage and imbibition experiments where microscopic phenomena are rather different due to changes in wettability properties of the fluids with respect to the surface. Capillary trapping (ganglions formation) may occur in imbibition experiments whereas in drainage experiments the wetting fluid that initially fills the porous media can be drained along the surface. On both cases, we measure the residual saturation as a function of the capillary number and study the influence of the viscosity ratio. This parameter plays a less important role on the displacement pattern in drainage experiments than in imbibition experiments. The comprehension of those phenomena is of great interest for Enhanced Oil Recovery (EOR) application. [Preview Abstract] |
Sunday, November 18, 2007 9:22AM - 9:35AM |
AQ.00005: Comparing two methods of simulating mirco-scale viscous flows in a porous channel Hui Gao, Jie Han, Yan Jin, Lian-Ping Wang Water flows in natural soil porous media are important to colloid-facilitated transport of contaminants and other phenomena with groundwater as the carrier. The 3D micro-scale flow is complicated due to the complex geometry. The transport and deposition of colloids in such flows are affected by several physical and chemical forces involved. In this talk, we first compare two methods of simulating viscous flows in both 2D and 3D channels filled with glass-bead particles. The first method is Physalis developed by Prosperetti's group, at Johns Hopkins, based on solving the Navier-Stokes equation using a combination of numerical solution and local analytical Stokes flow representation. The second method is a meso-scale approach by solving a lattice Boltzmann equation. Specific implementation issues will be discussed. The two methods yield almost identical flows. Preliminary simulation results as well as parallel experimental results on colloid deposition in the porous channel will also be presented. [Preview Abstract] |
Sunday, November 18, 2007 9:35AM - 9:48AM |
AQ.00006: Numerical Simulation of the behavior and mobilization of fine-grained quartz particles in porous media Michal Hradisky, Jeffrey Allen, Thomas Hauser The presentation focuses on the simulation of mobilization, deposition and detachment of fine-grained, quartz particles (hereafter referred to as ``fines'') to silica grains. Colloidal and hydrodynamic forces are computed and evaluated. In addition, the effects of differing levels of alkalinity and electrolyte concentration are evaluated per the Happel's model and the Derjaguin-Landau and Verwey-Overbeek (DLVO) theory. This theory allows for the initial attachment of the fine particle to the surface of a silica grain, by assuming that the electrolyte concentrations of the fluid medium are sufficiently high to warrant the domination of the attractive Van der Waal's forces. Multi-grained three dimensional simulation results for a centered cubic packing structure are presented. [Preview Abstract] |
Sunday, November 18, 2007 9:48AM - 10:01AM |
AQ.00007: A model for ion transport during drying of a porous medium Laura Guglielmini, Alexandre Gontcharov, Antonio Aldykiewicz, Howard Stone Salt crystallization at the surface or in the body of a porous medium has been recognized as a major mechanism in the deterioration of construction materials and historical monuments. Crystal formations on the surface of bricks, concrete, stones, called efflorescences, lead to fast obsolescence of building and monuments finishing, while crystal growth inside the material, called subflorescences, causes crack formation, which may lead to major structural damages. A number of studies have been devoted to the analysis of crystal growth in an elementary pore and aim at explaining the stress generated by crystallization. From a fluid mechanical point of view the physics of water transport and salt distribution in the porous medium turns out to be quite complex, since it is a function of the pore structure and wettability characteristics, of granule size and of the thermal properties of the material. It also depends on the transient environmental conditions the surface is exposed to and on the effective diffusivity of salt at different saturation conditions. We present here a simple theoretical model of the first phase of the drying process, during which water is uniformly distributed throughout the medium and often efflorescences occurs, which aims at characterizing the physics involved in the process. [Preview Abstract] |
Sunday, November 18, 2007 10:01AM - 10:14AM |
AQ.00008: Vibration effect on a stability of a displacement front Tatyana Lyubimova, Dmitriy Lyubimov, Grigoriy Sedelnikov Vibration effect on the stability of the displacement front between two immiscible fluids saturating porous medium is studied. Vibrations are orthogonal to the displacement front. Darcy model is implemented for the description of filtration. For high frequency vibrations it is shown in the framework of average approach that the vibrations make stabilizing effect. For finite-frequency vibrations the parametric instability zones are determined; it is found that both stabilization and destabilization of the displacement front are possible. For finite-amplitude perturbations numerical investigation based on unsteady non-linear equations is carried out by level set method for water-oil system saturating loamy soil. Temporal evolution of the displacement front shape is studied for various initial perturbations, vibration intensities and the displacement front motion velocity. The dependence of the time needed for the formation of isolated domains on the vibration intensity is obtained. It is found that the vibrations lead to the significant growth of perturbation wavelength and characteristic time scale of perturbation growth. [Preview Abstract] |
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