Abstract

In this paper, we consider a total dispersion tensor in two-dimensional packed beds consisting of randomly placed parallel cylinders for porosities between 38% to 90%, Peclet numbers up to 100 and Reynolds number up to 20 based on the cylinder diameter and filtration speed. The effective dispersivity is measured by computing the concentration field for a uniform gradient of concentration parallel and normal to the applied pressure gradient. In order to obtain statistically significant ensembles, a sufficiently large number of realizations are generated by repacking the domain and recomputing the dispersivity for porosity, Peclet number and Reynolds number. A comparison is made with transient numerical data in which a fixed concentration is imposed at the boundary. For the Reynolds numbers examined here, inertial effects are depicts to produce a relatively smaller effect, often resulting in a decrease in the dispersivity for a Peclet number. Porosity strongly effects dispersion normal to the bulk flow.

Key words: Dispersion, Inertial Flows, Reynolds number, Porous Effect,Dispersivity.