Interface physics in microporous media : LDRD final report.

Abstract

This document contains a summary of the work performed under the LDRD project entitled "Interface Physics in Microporous Media". The presence of fluid-fluid interfaces, which can carry non-zero stresses, distinguishes multiphase flows from more readily understood single-phase flows. In this work the physics active at these interfaces has been examined via a combined experimental and computational approach. One of the major difficulties of examining true microporous systems of the type found in filters, membranes, geologic media, etc. is the geometric uncertainty. To help facilitate the examination of transport at the pore-scale without this 4 complication, a significant effort has been made in the area of fabrication of both two-dimensional and three-dimensional micromodels. Using these micromodels, multiphase flow experiments have been performed for liquid-liquid and liquid-gas systems. Laser scanning confocal microscopy has been utilized to provide high resolution, three-dimensional reconstructions as well as time resolved, twodimensional reconstructions. Computational work has focused on extending lattice Boltzmann (LB) and finite element methods for probing the interface physics at the pore scale. A new LB technique has been developed that provides over 100x speed up for steady flows in complex geometries. A new LB model has been developed that allows for arbitrary density ratios, which has been a significant obstacle in applying LB to air-water flows. A new reduced order model has been developed and implemented in finite element code for examining non-equilibrium wetting in microchannel systems.These advances will enhance Sandia's ability to quantitatively probe the rich interfacial physics present in microporous systems. 5 ACKNOWLEDGMENTSWe would like to acknowledge the contributions of Joanne Fredrich who proposed this project and stewarded it during her time at Sandia. We would also like to acknowledge the work of both Mike Hickner and David Holdych who contributed to this work while at Sandia. We would also like to thank Raymond O. Cote for fabricating the cartridge for the micromodels and Brian Wroblewski and David J. Saiz for performing the photolithography work. 6 7