Unified Riemann solution for multi-physics coupling: Anisotropic poroelastic/elastic/fluid interfaces

Abstract

For wave propagation problems, we derive a closed expression of Riemann solvers for the interface between two distinct physics models with anisotropic material properties. For the interface coupling of anisotropic poroelastic/elastic/fluid media, the difficulty may arise from two aspects, including (1) different variable numbers from different physics regions and (2) the anisotropy-induced complexity. Fortunately, with a generalized wave impedance, the Riemann problems can be unifiedly solved in a compact and consistent way. The proposed Riemann solution plays a pivotal role for the discontinuous Galerkin time domain method, applied to wave propagation modeling in coupled poroelastic/elastic/fluid media. Numerical results are verified and validated with analytical solution and independent numerical solvers. Finally, we apply our algorithm to solve large-scale wave propagation in a fluid-infilled borehole configuration with heterogeneous poroelastic/elastic formations.