Comparison of sharp and smoothed interface methods for simulation of particulate flows I: Fluid structure interaction for moderate reynolds numbers

A Sharp Interface Method (SIM) with nominal second-order spatially accurate discretization and the Smoothed Profile Method (SPM) are compared as choices for the simulation of particulate flows. First, the issue of pressure oscillations that arise in moving boundary problems in using Sharp Interface Methods is addressed by developing a hybridized least-squares Ghost Fluid Method (GFM). SPM is modified by developing an interface thickness correlation that controls the smoothed (or diffuse) interface thickness based on the Reynolds and CFL numbers. SPM and SIM are tested for low to moderate Reynolds number flows around stationary and moving boundaries. SPM is shown to perform well on coarse grids while SIM is found to be more reliable and accurate on finer grids. SIM requires a hybridization approach to alleviate pressure oscillations for moving particles; in contrast, SPM does not present noticeable oscillations for the moving boundary problems tested. The results show that with a suitable correlation for setting the interface thickness in the SPM, the method is competitive against sharp interface approaches for particulate flows at moderate particle Reynolds numbers.