A comparison of body-fitted and immersed boundary methods for pore-scale modeling of fully saturated flow in synthetic porous media

We compare the performance of two numerical approaches to simulate pore-scale flow in randomly generated porous media under fully saturated conditions. The governing system of flow equations is solved via a Body-Fitted (BF) meshing approach and an Immersed Boundary (IB) method, respectively embedded in the ANSYS FLUENT (ANSYS FLUENT, 2009) and EULAG (Prusa et al., 2008) software environments. Mesh resolution dependence is tested for the BF method upon comparing simulations at three different levels of resolution with ANSYS FLUENT. A preliminary sensitivity analysis is performed with EULAG to identify the proper parameter setting for the IB implementation. The results of the two methods are then compared in terms of pore-scale flow fields (Eulerian velocity distributions) and macroscopic quantities (mean Darcy flux and permeability estimates) as well as mass-conservation capability