Bulletin of the American Physical Society
65th Annual Meeting of the APS Division of Fluid Dynamics
Volume 57, Number 17
Sunday–Tuesday, November 18–20, 2012; San Diego, California
Session H29: Porous Media Flows V |
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Chair: Paulo Arratia, University of Pennsylvania Room: 32B |
Monday, November 19, 2012 10:30AM - 10:43AM |
H29.00001: Impacts of Transport Properties of Porous Corrosion Product Layer on Effective Corrosion Rate Xiaobai Li, David Cook Condensing exhaust gases containing H$_{2}$O, SO$_{3}$ and NO$_{x}$ cause serious corrosion failure in various industry processes. For example, in modern compact heat cells, corrosion products deposit on top of the heat exchanger cooling fins, blocking the flow passages and drastically decreasing system performance. The transport properties of porous corrosion product layers play important role in determining the corrosion tendency and observed corrosion rate. To understand the corrosion mechanism for Aluminum alloy in sulfuric acid environment, impacts of transport properties of corrosion residual layers are investigated with different numerical models for porous layer diffusivity. The effective corrosion rates resulted from these models are compared to corresponding experimental measurements. A multilayer diffusivity model in which diffusivity depends both on porous layer structure and composition shows excellent agreements with experimental data. This model is currently being used in a multi-scale flow simulation framework to predict corrosion phenomena in heat cells. [Preview Abstract] |
Monday, November 19, 2012 10:43AM - 10:56AM |
H29.00002: Overlimiting current and water purification in porous materials Daosheng Deng, Wassim Aouad, Sven Schlumpberger, Martin Z. Bazant Salt transport in bulk electrolytes occurs by diffusion and convection, but in microfluidic devices and porous media, the presence of charged side walls leads to additional surface transport mechanisms, surface conduction and electro-osmotic flows, which become more important as the bulk salt concentration decreases. As a result, it is possible to exceed the diffusion-limited current to a membrane or electrode. In this work, we present experimental observations of over-limiting current to an ion-exchange membrane through a porous glass frit with submicron pores. Under this operation conditions, we also demonstrate the continuous extraction of depleted solution for water purification, including removing heavy metal ions, filtrating aggregated particles and reducing dye concentration. The porous media pave the way for practical water desalination and purification. [Preview Abstract] |
Monday, November 19, 2012 10:56AM - 11:09AM |
H29.00003: ABSTRACT WITHDRAWN |
Monday, November 19, 2012 11:09AM - 11:22AM |
H29.00004: Ion transport through a charged cylindrical membrane pore contacting stagnant diffusion layers Mathias B. Andersen, P.M. Biesheuvel, Martin Z. Bazant, Ali Mani Fundamental understanding of the ion transport in membrane systems by diffusion, electromigration and advection is important in widespread processes such as de-ionization by reverse osmosis and electrodialysis and electro-osmotic micropumps. Here we revisit the classical analysis of a single cylindrical pore, see e.g. Gross and Osterle [J Chem Phys \textbf{49}, 228 (1968)]. We extend the analysis by including the well-established concept of contacting stagnant diffusion layers on either side of the pore; thus, the pore is not in direct equilibrium with the reservoirs. Inside the pore the ions are assumed to be in quasi-equilibrium in the radial direction with the surface charge on the pore wall and we obtain a 1D model by area-averaging. We demonstrate that in some extreme limits this model reduces to simpler models studied in the literature; see e.g. Yaroshchuk [J Membrane Sci \textbf{396}, 43 (2012)]. Using our model we present predictions of important transport effects such as variation of transport numbers inside the membrane, onset of limiting current, and transient dynamics described by the method of characteristics. [Preview Abstract] |
Monday, November 19, 2012 11:22AM - 11:35AM |
H29.00005: Reactive geochemical transport modeling of CO$_{2}$ in porous media Mohammad Alizadeh Nomeli, Amir Riaz In this study the modified Redlich-Kwong equation of state is used to develop a pressure-volume-temperature-composition (PVTx) model that predicts how temperature, pressure and salinity affect the solubility of the supercritical CO$_{2}$ in brine and is subsequently employed to determine the density and rate of mineral trapping of CO$_{2}$ in the form of precipitates. Rates of dissolution and precipitation of minerals are determined by taking into account the pH of the system, in addition to the consideration of the influence of temperature. This study also presents a model to simulate a reactive fluid within permeable porous media. Fluid convection, diffusion and chemical reactions inside a finite space are considered as a simplified representation of natural mineral trapping. The purpose of the current study is to show the time evolution of the aperture shrinkage caused by precipitation of calcite. Precipitation of calcite decreases the porosity and subsequently can change the permeability. Permeability of the porous media controls the path of aqueous CO$_{2}$ migration; therefore the aperture width has a pivotal role on solubility and mineral trapping of injected CO$_{2}$. The current model predicts the actual efficiency of the mineral trapping mechanism. [Preview Abstract] |
Monday, November 19, 2012 11:35AM - 11:48AM |
H29.00006: Relevance of Linear Stability Results to Enhanced Oil Recovery Xueru Ding, Prabir Daripa How relevant can the results based on linear stability theory for any problem for that matter be to full scale simulation results? Put it differently, is the optimal design of a system based on linear stability results is optimal or even near optimal for the complex nonlinear system with certain objectives of interest in mind? We will address these issues in the context of enhanced oil recovery by chemical flooding. This will be based on an ongoing work. [Preview Abstract] |
Monday, November 19, 2012 11:48AM - 12:01PM |
H29.00007: Sustained Reaction Waves Against Flow in Porous Medium: Frozen Fronts Dominique Salin, Severine Atis, Harold Auradou, Sandeep Saha, Laurent Talon Autocatalytic reactions lead to fronts propagating as solitary, self-sustained, waves with a constant velocity and an invariant, flat, concentration profile resulting from a balance between reaction and diffusion. In the presence of a hydrodynamic flow, such fronts, while propagating at a new constant velocity, adapt their shape in order to achieve a balance between reaction diffusion and flow advection all over the front. The issue addressed here is the behaviour of autocatalytic reaction fronts when the forced advection is a heterogeneous flow field. It has been recently observed that in inside a porous medium there exist static, frozen, fronts over a wide range of mean flow rates in the opposite direction of the chemical wave propagation. To account for this dynamical equilibrium where the front is pinned at different points, we use both designed experiments around different configurations of solid obstacles and lattice Boltzmann numerical simulations which allows a control of the flow field heterogeneities. These approach allows us to account for the dependence of the range of observation of frozen states with th control parameters. In the case of the porous medium flow field, the transition to this frozen state is understood in term of percolation like path. [Preview Abstract] |
Monday, November 19, 2012 12:01PM - 12:14PM |
H29.00008: The ``coffee-ring effect'' as a way to remove pollutants and control drying rate in porous media Emmanuel Keita, Pam\'ela Faure, St\'ephane Rodts, David A. Weitz, Philippe Coussot Due to the transport of elements they induce imbibition-drying cycles are known to play a major role in the colloid-facilitated transport in soils and building materials. We study the drying of a colloidal suspension in a porous media. The critical physical phenomenon at work here is the displacement and redistribution of colloidal particles or ions induced by evaporation of the liquid phase from the porous medium. This can be clearly seen by filling a bead packing with coffee. Indeed after full drying the sample has shaded tones with darker regions around the sample free surface and white regions almost free of particles around the bottom. The mechanisms are not yet fully understood and there is no straightforward observation and simple quantification of the spreading of the elements. Using a new MRI technique to look at a complex porous media with colloidal particles in suspension in water we show that the drying of a porous medium filled with elements in the advection regime develops a specific coffee-ring effect. We can quantify how the elements migrate towards the free surface of the sample and accumulate in the remaining liquid films. Our complete understanding of the process makes it possible to establish a simple model predicting the drying rate and the concentration distribution. This opens the way to a control of salt or colloid transport and drying rate of soils and building materials. [Preview Abstract] |
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