Generalized Darcy's Law for Filtration Processes in Porous Media

The liquid flow in a porous medium is considered for the axially-symmetric case. The generalization of the Darcy's filtration law is suggested and the explanation of the so-called "near-wall" effect is given. The filtration efficiency is estimated for filters of two possible geometries: cylindrical and radial ones. As an illustration we consider also the case of the cylindrical filter with a bi-layer filling.