Numerical modelling of waves in double-porosity Biot medium

Abstract

We consider acoustic waves in fluid-saturated periodic media with large contrasts in the permeability and other poroelastic coefficients, whereby some of the mesoscopic material parameters depend on the scale parameter. The effective behaviour is described by a model obtained using the homogenization of the heterogeneous Biot continuum relevant to the mesoscopic level at which the dual porosity is featured by low permeability, whereas the primary porosity is very compliant. All material coefficients of the homogenized model depend on the frequency of incident waves. The macroscopic fields can be employed to reconstruct solutions at the mesoscopic level relevant to the heterogeneities. To validate the model, we consider heterogeneous strips with a finite scale lattice defining the heterogeneity. For such structures, the recovered mesoscopic response computed using the numerical homogenization method is compared with direct numerical simulations for various contrasts. For media featured by large contrast the double porosity model provides much better estimates of the wavelengths and other dispersion properties than the standard single porosity homogenized model. Moreover, the performed tests show computational efficiency of the two-scale simulations using the homogenized model, while the direct simulations of a heterogeneous medium become unfeasible because of requirements on the finite element discretization.