Coupling Free Flow and Porous Medium Flow Systems Using Sharp Interface and Transition Region Concepts

Abstract

Two different coupling approaches for isothermal single-phase free flow and isothermal single-fluid-phase porous medium systems are considered: sharp interface and transition region approach. The sharp interface concept implies the Beavers–Joseph–Saffman velocity jump condition together with restrictions that arise due to mass conservation and balance of normal forces across the fluid-porous interface. The transition region model is derived by means of the thermodynamically constrained averaging theory (TCAT). The equations are averaged over the thickness of the transition zone in the direction normal to the free flow and porous medium domains being joined. Coupling conditions are the mass conservation, the momentum balance and a generalization of the Beavers–Joseph condition. Two model formulations are compared and numerical simulation results are presented. For discretization of the coupled problem the finite volume method on staggered grids is used.