Numerical comparison of the equivalent continuum, non-homogeneous and dual porosity models for flow and transport in fractured porous media

The main objective of this work is to compare three different models for modelling of flow and solute transport in fractured porous media, in terms of their predictions of the flow and solute transport field variables. The three models are: the equivalent continuum model, the dual porosity model and the discrete fracture/non-homogeneous model. Though it is clear that the three models are based on different assumptions for their validity, it is not clear in which cases two or all of them would give similar results, since there are no such reported comparisons in the open literature. The three methods are compared for two different geometries: a rectangular porous domain with two parallel fractures and a square porous domain with regular mesh of three parallel fractures and another three fractures perpendicular to the first ones. The results helped to draw some conclusions in respect to the similarity of potentials as well as fluxes for the different methods for each of the two geometries. In this research the boundary element dual reciprocity method–multi domain scheme (BE DRM–MD) has been used and its implementation has been described. This numerical scheme has been used for the first time to solve a dual-porosity model. The scheme showed satisfactory accuracy and high flexibility in preparation of the discrete fracture/non-homogeneous meshes.