Slip condition on the surface of a model fibrous porous medium

We have solved the problem of a creeping two-dimensional shear flow of a viscous incompressible fluid in a flat channel partially filled with a fibrous porous medium, which is modeled by a regular lattice of square cylinders arranged across the flow. The hydrodynamic microscopic velocity fields are determined by numerical methods. The slip coefficient at an effective boundary of the model porous medium is evaluated by macroscopic averaging.