Impurity transport in the model of a dual-porosity regularly heterogeneous medium with colloids

The problem of impurity advection in a channel surrounded by a weakly permeable medium with drifting colloidal particles present in the channel is solved. A regime in which the front of the impurity cloud moves with a constant velocity and the concentration behind the front decreases as a power law is established due to the impurity adsorption on colloids and its diffusive exchange with the matrix on moderate time scales. On long time scales, the transport in the channel is quasi-diffusive as a result of the impurity desorption and its eventual escape into the matrix.