Intrinsic Dispersivity of Randomly Packed Monodisperse Spheres

Tracer dispersion in noninertial flow through random porous media is of considerable importance in catalysis, chromatography, ground water flows, oil production, and soil contamination, and it is a fundamental problem of hydrodynamics. Absent macroscopic stagnation zones, it is governed by differential advection in a nonuniform velocity field coupled to diffusion along velocity gradients perpendicular to the local flow. In laminar flow through a pipe [1‐3] the pipe radius a sets the spatial scale for the velocity gradients. In a simple isotropic random porous medium, realized approximately in the laboratory with a random pack of identical spheres (RP), the equivalent length is given by the volume to surface ratio of the pore