Solute transport through porous media with scale-dependent dispersion and variable mass transfer coefficient

Abstract

In this paper, we investigate the behavior of breakthrough curves in mixed heterogeneous soil column experiments. Advective dispersive transport equations are used for solute transport through mobile–immobile porous medium. A hybrid finite volume method is used to solve the governing equations for solute concentration in mobile region. In first part of the study, constant dispersion, linear, and asymptotic distance-dependent dispersion functions are used to describe the scale effect and to simulate experimental breakthrough curves observed in long soil column experiment. Also, a comparative study has been done among distance-dependent and constant dispersion models, while simulating the experimental data of solute transport through soil column with constant mass transfer coefficient. In second part of the study, variable mass transfer coefficient as function of pore velocity and travel distance is considered and an empirical relation is derived from observed data from experiments. It is shown that asymptotic dispersion model with variable mass transfer coefficient simulates the observed breakthrough curves better as compare to constant and linear distance-dependent dispersion models. Finally, present study also shows that the value of mass transfer coefficient is dependent on pore velocity and movement of solute through porous media.