Derivation of matching conditions at the contact surface between fluid-saturated porous solid and bulk fluid

The compatibility conditions matching macroscopic mechanical fields at the contact surface between fluid-saturated porous solid and adjacent bulk flui d are considered. Special attention is paid to the derivation of conditions for tangential components of the fluid how velocities and to the verificat ion of validity of the condition postulated by Beavers and Joseph. It has b een shown that at the contact surface between two media, a dissipation of m echanical energy due to the fluid viscosity does exist and thus the form of a dissipation function has been proposed. It has been proven that this rel ation determines the form of two linear compatibility conditions derived fo r the tangential components of the relative fluid velocities and that these conditions describe the experimental results more precisely than the condi tion postulated by Beavers and Joseph.