Tracer diffusion in a Brownian fluid permeating a porous medium

Tracer diffusion in a colloidal suspension permeating a porous medium is modeled as a binary Brownian mixture in which the spatial configuration of one of the species (the porous matrix) is frozen. Brownian dynamics simulations are employed to assess the accuracy of two simple theoretical results borrowed from the theory of colloid dynamics. The theoretical predictions are found to be reasonably accurate for not too low porosities, i.e., when strong confinement or trapping of tracer particles is not the dominant feature. © 1995 The American Physical Society.

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