STOCHASTIC TRANSPORT IN HETEROGENEOUS MEDIA WITH MULTIPLE FAMILIES OFTRANSPORT PATHS

We examine in detail a model for transport in heterogeneous solids and porous media which contain N distinct families of transport paths (wi th N greater-than-or-equal-to 2), recently proposed by the authors [Ph ys. Rev. Lett. 70, 2581 (1993)]. The model is relevant to transport in metals, polycrystals, porous catalysts, coalbed methane reservoirs, a nd geological systems with fractures and pores. We develop a number of exact results for the one-dimensional case and, more generally, study the behavior of its effective transport properties using an effective -medium approximation, which yields several exact results in one spati al dimension.