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 D29: Porous Media Flows II |
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Chair: Dimitrios Papavassiliou, University of Oklahoma Room: 32B |
Sunday, November 18, 2012 2:15PM - 2:28PM |
D29.00001: Distribution of flow-induced stresses in the pore space of random porous media Dimitrios Papavassiliou, Ngoc Pham The distributions of stresses in the pore space of packed-sphere beds when a fluid flows through the porous medium under Darcy flow conditions are numerically computed with Lattice Boltzmann simulations. Three different ideally-packed (i.e., face-centered cubic, body-centered cubic and simple cubic packing) and one randomly-packed configuration of the packed bed are considered. It is found that the probability density function of the stresses, when the stresses are normalized with the mean value and the standard deviation of the distribution, behaves in different modes when the packing type changes. In the Darcy regime, the normalized stress distribution of a particular packing type is independent of the pressure difference and presents a unique pattern. The most important finding is that a log-normal distribution can successfully fit the stress distributions in the simulated randomly packed beds with high statistical accuracy. The applicability of the log-normal distribution is also explored for other types of porous media, and it is found that it is likely applicable for porous media with random pore space configurations. [Preview Abstract] |
Sunday, November 18, 2012 2:28PM - 2:41PM |
D29.00002: The porous medium permeability and effective diffusion coefficient direct correlation Bojan Markicevic Dimensionless analysis of a momentum and mass transport in the homogeneous porous medium reveals that the permeability and effective to the molecular diffusion coefficient ratio can be expressed as a function of medium pore and throat sizes and two additional geometrical scales. These two scales, each one pertinent to the momentum and mass transport, respectively, are referred to as permeability and diffusivity characteristic scales. Based on these findings, it can be shown that the medium permeability and effective diffusivity can be correlated, and, at the same time, that one microscopic scale needs to be known in this correlation. The same is implied from the Katz-Thompson formula - which correlates the permeability, effective diffusivity, and breakthrough capillary pressure length scale. We recast the correlation developed into the Katz-Thompson formula form, showing how corresponding members are related. It turns out that the coefficient from the Katz-Thompson formula is equal to the ratio of the permeability to diffusivity characteristic length scales, and it is indeed constant for the homogeneous media. As porous media are heterogeneous materials, the analysis is extended onto such materials using heterogeneous capillary networks. The networks with the uniform, normal and \textit{log}-normal pore size distribution functions are generated, where the networks are sufficiently large to obtain small variations in permeability and effective diffusivity for pore size distribution set. For such stochastically homogeneous media, the effective pore size averages are used in calculating the permeability and effective diffusivity showing the true nature of the coefficient in the Katz-Thompson formula. [Preview Abstract] |
Sunday, November 18, 2012 2:41PM - 2:54PM |
D29.00003: Capillary pinning of immiscible gravity currents in porous media Benzhong Zhao, Christopher MacMinn, Michael Szulczewski, Herbert Huppert, Ruben Juanes Gravity currents in porous media have attracted much interest recently in the context of geological carbon dioxide (CO2) storage, where supercritical CO2 is injected underground into deep saline aquifers. Capillary effects can be very important in the spreading and migration of the buoyant CO2 after injection because the typical pore size is very small ($\sim$10-100 $\mu$m), but the impact of capillarity on these flows is not well understood. Here, we study the impact of capillarity on a finite-release gravity current of a buoyant non-wetting fluid. Via simple, table-top experiments, we show that capillary pressure hysteresis causes pinning of a portion of the initial interface, which ultimately stops the spreading of the buoyant current at a finite distance. In addition, capillarity causes blunting at the leading edge of the draining buoyant current. We demonstrate through micromodel experiments that the height of the nose of the current is controlled by the pore geometry as well as the balance between capillarity and gravity. Our analysis suggests that capillary pinning and capillary blunting exert a fundamental control on the interface evolution of immiscible finite-release gravity currents in the context of CO2 sequestration in deep saline aquifers. [Preview Abstract] |
Sunday, November 18, 2012 2:54PM - 3:07PM |
D29.00004: Fluid Drainage from Porous Reservoirs Zhong Zheng, Beatrice Soh, Herbert Huppert, Howard Stone We report theoretical and experimental studies to describe buoyancy-driven fluid drainage from a porous medium. We first study homogeneous porous systems. To investigate the influence of heterogeneities, we consider the case where the permeability varies transverse to the flow direction, exemplified by a V-shaped Hele-Shaw cell. Finally, we analyze a model where both the permeability and the porosity vary transverse to the flow direction. In each case, a self-similar solution for the shape of the gravity current is found and a power-law behavior in time is derived for the mass remaining in the system. Laboratory experiments are conducted in homogeneous and V-shaped Hele-Shaw cells, and the measured profile shapes and the mass remaining in the cells agree well with our model predictions. Our study provides new insights into drainage processes such as may occur in a variety of natural and industrial activities including the geological storage of carbon dioxide. [Preview Abstract] |
Sunday, November 18, 2012 3:07PM - 3:20PM |
D29.00005: A Solutal Fingering Instability during Capillary Imbibition in Porous Media W.D. Ristenpart, N.J. Young, C.J. Guido We report the existence of a solute-driven fingering instability that occurs during capillary imbibition into cellulosic porous media. Contacting a piece of paper with an aqueous solution containing hydrophobic solutes causes the liquid to move forward into the paper. For sufficiently low solute concentrations and sufficiently high ambient humidities, the imbibition front moves forward smoothly as expected. For higher concentrations and lower humidities, however, the imbibition front develops spatially periodic oscillations that grow with time, i.e., a fingering instability occurs. Surprisingly, under these conditions the solute concentration becomes larger at the imbibition front compared to the bulk, contrary to the behaviour expected based on chromatographic separation. We demonstrate that fingering instabilities occur with a wide variety of solutes and paper types, and we propose that the instability is driven by solute-induced changes in the air/liquid interfacial tension as liquid is absorbed into a humidity-dependent precursor film. [Preview Abstract] |
Sunday, November 18, 2012 3:20PM - 3:33PM |
D29.00006: ABSTRACT WITHDRAWN |
Sunday, November 18, 2012 3:33PM - 3:46PM |
D29.00007: ABSTRACT WITHDRAWN |
Sunday, November 18, 2012 3:46PM - 3:59PM |
D29.00008: Scaling laws for the imbibition of textured surfaces comprising short pillars with rounded edges Ko Okumura, Noriko Obara, Minako Hamamoto-Kurosaki Imbibition of porous media has been useful in many practical applications, e.g. to realize ultra-slippery surf surfaces. However, fundamental physical understandings are still limited. Recently, two scaling regimes are identified for the imbibition of textured surfaces comprising long pillars with sharp edges [1,2]. Here, we study textured surfaces comprising short pillars with rounded edges [3]. As a result, we find different scaling regimes for the dynamics. Surprisingly, this law is universal in the sense that it is independent of texture geometry, i.e., of pillar height, pillar distances, and pillar radius. \\[4pt] [1] Chieko Ishino, Mathilde Reyssat, Etienne Reyssat, Ko Okumura and David Quere, Europhys. Lett. 79 (2007) 56005. \\[0pt] [2] Minako HAMAMOTO-KUROSAKI and Ko OKUMURA, Eur. Phys. J. E 30, 283-290 (2009)\\[0pt] [3] Noriko OBARA and Ko OKUMURA, Phys. Rev. E Rapid Communication (in press 2012). [Preview Abstract] |
Sunday, November 18, 2012 3:59PM - 4:12PM |
D29.00009: Imbibition in porous media Bertrand Levache, Denis Bartolo, Maurice Bourrel We study imbibition of wetting fluid into a uniform porous media made using microfluidic's techniques. We first revisit each phase of the diagram proposed by Lenormand. We then identify an invasion process that has not been seen until now where the invading fluid progress as thin films along the walls of the media. This modifies the problem by changing flows from two to three dimensions. Finally, we focus on this new phase, giving clues for the understanding of its dynamics and characterize it from a morphological point of view. [Preview Abstract] |
Sunday, November 18, 2012 4:12PM - 4:25PM |
D29.00010: Oil drainage in model porous media by viscoelastic fluids Julien Beaumont, Hugues Bodiguel, Annie Colin Crude oil recovery efficiency has been shown to depend directly on the capillary number (Ca). If the capillary phenomenon is well described for Newtonian fluids, the consequences of non linear rheology and viscoelasticity require more experimental work at the pore scale. In this work we take advantage of microfluidic to revisit this field. We carried out oil drainage experiments through a micromodel made up with photoresist resin. The wetting phase trapped is a model oil. The invading phases used are aqueous solutions of high molecular weight hydrolyzed polyacrylamide (HPAM) and surfactant. Qualitatively, we observed a transition between a capillary fingering at low flow rates and a stable front at high flow rates for the drainage experiments with HPAM and surfactant solutions as it happened for drainage with Newtonian fluids. From movies of the filling of the device, we determine the local velocity of all menisci in the porous media. Thus, we quantify the capillary fingering. Surprisingly, local velocities are not significantly different from those measured using water, whereas the HPAM solutions are much more viscous. With betaine solutions, we observed an emulsification of the oil clusters trapped during the invasion leading to a very high oil recovery after percolation. [Preview Abstract] |
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