ELECTRICAL-CONDUCTION AND FORMATION FACTOR IN ISOTROPIC POROUS-MEDIA

A macroscopic form of Ohm's law is obtained for isotropic porous media saturated with an electrically conductive fluid by using volumetric a veraging concepts. Closure of the macroscopic charge transport equatio n is aided by approximative modelling of the average geometric structu res of three different types of isotropic porous media, namely foamlik e materials, granular media and crossflow over prismatic bundles. Mode lling of the microscopic charge transport necessitated the introductio n of a representative interstitial flux of charge carriers and require d quantification of the geometric tortuosity applicable to transport p henomena in general. Deterministic expressions for the formation facto r are obtained and compare favourably with experimental results. Copyr ight (C) 1996 Elsevier Science Limited