MACROSCOPIC ELECTROOSMOTIC COUPLING COEFFICIENT IN RANDOM POROUS MEDIA

Abstract

A general analysis of electroosmotic phenomena is given for random porous media through which an electrolyte flows. A dimensional analysis demonstrates the crucial importance of the dimensionless coupling parameter a, which is usually very small when compared to 1; this suggests an expansion in terms of a and a numerical scheme that avoids the instabilities occurring in the direct solution. For media whose properties such as permeability are lognormally distributed, an analytical expression of the macroscopic coupling coefficients can be obtained when the fluctuations are small. Various results are provided for laminated media, correlated media, and stratified or fractured media. The influence of some macroscopic geometrical parameters is illustrated.