Flow Around a Crack in a Porous Matrix and Related Problems

The equations governing plane steady-state flow in heterogeneous porous body containing cracks are presented first. Then, a general transformation lemma is presented which allows extending a particular solution obtained for a given flow problem to another configuration with different geometry, behaviour and boundary conditions. An existing potential solution in terms of discharges along the cracks, established by Liolios and Exadaktylos (J Solids Struct 43:3960-3982, 2006) for non-intersecting cracks in isotropic matrix, is extended to intersecting cracks in anisotropic matrix. The basic problem of a single straight crack in an infinite body submitted to a pressure gradient at infinity is then investigated and a closed-form solution is presented for the case of void cracks (infinite conductivity), as well as a semi-analytical solution for the case of cracks with Poiseuille type conductivity. These solutions, derived first for an isotropic matrix, are then extended to anisotropic matrices using the general transformation lemma. Finally, using the solution obtained for a single crack, a closed-form estimation of the effective permeability of micro-cracked porous materials with weak crack density is derived from a self-consistent upscaling scheme.