Dispersion of solute in wall-bounded parallel shear flows

Abstract

For laminar dispersion in wall-bounded straight channels, a rigorous method of solution to the basic convective diffusion equation is developed by using the Green's function. The method leads to a self-consistent and computationally useful procedure for the determination of the concentration distribution at arbitrary times. The dispersion approximation of Gill and Sankarasubramanian [5,6] and the alternative approach of Smith [14, 15] for the transverse mean concentration are critically examined. It is shown that these latter methods are valid only under restricted conditions. For initial-value problems where the dispersion approximation applies, a purely algebraic method, distinctively different from the work of DeGance and Johns [10, 11] for the determination of the dispersion coefficients is developed.