Concentration gradient, diffusion, and flow through open porous medium near percolation threshold via computer simulations

The interacting lattice gas model is used to simulate fluid flow through an open percolating porous medium with the fluid entering at the source-end a nd leaving from the opposite end. The shape of the steady-state concentrati on profile and therefore the gradient field depends on the porosity (p). Th e root mean square (rms) displacements of fluid and its constituents (trace rs) show a drift power-law behavior, R proportional to t in the asymptotic regime (t --> infinity). The flux current density (j) is found to scale wit h the porosity according to, j proportional to (Deltap)(beta) with Deltap = p - p(c) and beta similar or equal to 1.7. (C) 2001 Published by Elsevier Science B.V.