Estimation of hydrodynamic dispersion in a fine sand using an approximate analytical solution

Abstract

The quasi-analytical approach to hydrodynamic dispersion during horizontal absorption under constant concentration conditions is discussed, and it is shown that the pore water velocity reaches a maximum at the ë value where g(ë) =0. The resulting small variations in pore water velocity that occur across the solute front and the relative constancy of water content in that region during absorption in a fine sand allow an approximate analytical solution for velocity-dependent hydrodynamic dispersion to be formulated. The equation is tested against computer-based numerical solutions for both horizontal absorption and vertical infiltration. The predictive quality of the approximate analytical solution is found to be very good for the systems examined.