Extraction from a porous body in the presence of periodic fluid flow on it

This paper considers the nonstationary process of extraction from a solid body modeled by a system of semiinfinite capillaries connected with a group of no-flow channels when the mass transfer velocity in the flow is composed of two components — a constant velocity component and a time-periodic addition to the first one that is assumed to be small relative to the amplitude. We have obtained analytical dependences for the masstransfer characteristics that are of practical interest: the concentration and the diffusion flow for both the main approximation and with correction for the periodic action on the system.