Asymptotic and numerical modelling of flows in fractured porous media

Philippe Angot (1) , Franck Boyer (1) , Florence Hubert (1)

1 LATP - Laboratoire d'Analyse, Topologie, Probabilités

This study concerns some asymptotic models used to compute the flow outside and inside fractures in a porous medium. The flow is governed by the Darcy law both in the fractures and in the porous matrix with large discontinuities in the permeability tensor. These fractures are supposed to have a small thickness with respect to the macroscopic length scale, so that we can asymptotically reduce them to immersed polygonal fault interfaces and the model finally consists in a coupling between a d-dimensional elliptic problem and a (d-1)-dimensional one on the sharp interfaces modelling the fractures. A cell-centered finite volume scheme on general poly\-gonal meshes fitting the interfaces is derived to solve the set of equations with the additional differential transmission conditions linking both pressure and normal velocity jumps through the interfaces. We prove the convergence of the FV scheme for any set of data and parameters of the models and derive existence and uniqueness of the solution to the asymptotic models proposed. The models are then numerically experimented for fully or partially immersed fractures. Some numerical results are reported showing different kinds of flows in the case of impermeable or partially/fully permeable fractures. The influence of the variation of the aperture of the fractures is also investigated. The numerical solutions of the asymptotic models are validated by comparing them to the solution of the global Darcy model or to some analytic solutions.

Mots clés: Fractured porous media; Darcy flow; Finite volume method; Asymptotic models of flow

Domaines: Analyse numérique [math.NA]

Philippe Angot, Franck Boyer, Florence Hubert. Asymptotic and numerical modelling of flows in fractured porous media. 2007. ⟨hal-00127023v1⟩