Summary Macroscopic constitutive equations for an inhomogeneous and anisotropic porous medium are constructed by volume averaging pore scale constitutive equations. The porous medium considered, consists of an elastic solid with interconnected void spaces filled with a chemically inert viscous fluid. Two constituents are assumed homogeneous in their material properties, but porosity is spatially varying. Points of con tact with Biot''s(1962) work are established.
Introduction A porous medium, viewed as an elastic matrix filled with Viscous fluid is a realistic model for earth material frequently encountered in oil, gas or water explorations. In such a context, in homogeneity or anisotropy can readily arise from uneven manners in which pores and interfaces are distributed. In particular, the porosity can change from place to place due, for example, to compaction. This model has been studied carefully by Biot over many years, culminating in the widely-accepted Biot(1962) theory.