Steady-state saturated groundwater flow modeling with full tensor conductivities using finite differences

We present a new 3D steady-state saturated groundwater-flow forward-simulator with full conductivity tensors using a 19-points block-centered finite-difference method. Hydraulic conductivity tensors are defined at the block interfaces eliminating the need to average conductivity tensors at adjacent blocks to approximate their values at the interfaces. The capabilities of the code are demonstrated in three heterogeneous formulations, two of the examples are 2D, and the third one is 3D and uses a nonuniform discretization grid. A benchmark, in the context of conductivity upscaling, is carried out with the MODFLOW LVDA module, which uses hydraulic conductivity tensors at block centers and then approximates their values at the interfaces. The results show that our code gives more accurate predictions for the interblock fluxes than the MODFLOW LVDA module when the block conductivity principal directions are not parallel to the Cartesian axis.