Finite element lattice Boltzmann method for fluid flow through complex fractured media with permeable matrix

This study proposed an improved finite element based generalized lattice Boltzmann model (FE-GLBM) to simulate the fluid flow in extremely heterogeneous porous media, in which the generalized lattice Boltzmann equations proposed by Guo and Zhao (2002) are solved using the characteristic Galerkin finite element method (GFEM), and the FEM is applied to improve the flexibility of GLBM and to optimize the flow simulation in complex geometries. An image-based automatic meshing method is adopted to generate advanced unstructured mesh of the structure. The proposed numerical model is validated with analytical results, finite-difference results, and previously published data in three cases, including the generalized two-dimensional Poiseuille flow, the lid-driven cavity flow, and the circular cylinder flow, respectively. The sensitivity study of the fluid flow in three-dimensional fractured porous media with a disordered fracture network and permeable matrix is carried out as a practical application example, and the results indicate that the matrix permeability plays an important role in controlling the flow dynamics in fractured porous media.