A new conforming mesh generator for three-dimensional discrete fracture networks

Nowadays, numerical modelings play a key role in analyzing hydraulic problems in fractured rock media. The discrete fracture network model is one of the most used numerical models to simulate the geometrical structure of a rock-mass. In such media, discontinuities are considered as discrete paths for fluid flow through the rock-mass while its matrix is assumed impermeable. There are two main parameters to simulate the geometry of discontinuities in this model; the density and connectivity pattern of fractures. Despite the advantages of the discrete fracture network modeling, in order to apply the numerical solution schemes, the discretization of this model has encountered serious challenges due to the geometrical complexities. Generally, some of previous meshing methods present a framework that changes the geometrical structure and connectivity pattern of the model, and some others are incapable to mesh intricate networks with a large number of fractures. In this research, a new algorithm is developed to mesh the geometrical framework of three-dimensional discrete fracture networks. This algorithm is designed based on a refined conforming Delaunay triangulation and is computationally efficient, fast and low-cost. Furthermore, it never changes the geometrical structure of a DFN primitive model, therefore, the connectivity pattern will remain intact and the mesh is a proper representative of DFN. The algorithm was validated using the analytical methods and a series of sensitivity analysis was performed to evaluate the effect of meshing parameters on fluid flow using a finite element scheme of steady state Darcy flow. The results show that an optimized minimum internal angle of meshing elements should be predetermined to guarantee termination of the algorithm.

Keywords:

Meshing , Conforming mesh , DFN , Delaunay , FEM