Macroscopic electroosmotic coupling coefficient in random porous media

A general analysis of electroosmotic phenomena is given for random porous m edia through which an electrolyte flows. A dimensional analysis demonstrate s the crucial importance of the dimensionless coupling parameter a. which i s usually very small li hen compared to I: this suggests an expansion in te rms of a and a numerical scheme that avoids the instabilities occurring in the direct solution. For media whose properties such cis permeability are l ognormally distributed, tin analytical expression of the macroscopic coupli ng coefficients can be obtained when the fluctuations are small. Various re sults are provided for laminated media, correlated media, and stratified or fractured media. The influence of some macroscopic geometrical parameters is illustrated.