Direct numerical simulation of polygonal particles sedimentation with collisions

An original Direct Numerical Simulation (DNS) method to tackle the problem of particulate flows at moderate to high concentration and finite Reynolds number is presented. Our method is built on the framework established by Glowinski and his coworkers [1] in the sense that we use their Distributed Lagrange Multiplier/Fictitious Domain (DLM/FD) formulation and their operator-splitting idea but differs in the treatment of particle collisions. The novelty of our contribution relies on replacing the simple artificial repulsive force based collision model usually employed in the literature by an efficient Discrete Element Method (DEM) granular solver. The use of our DEM solver enables us to consider particles of arbitrary shape (at least convex) and to account for actual contacts, in the sense that particles actually touch each other, in contrast with the simple repulsive force based collision model. Results on the 2D sedimentation of isometric polygonal particles with collisions are presented. These new results underline the promising capabilities of GRIFF (GRains In Fluid Flow), our numerical code, to study a wide range of particulate flow problems and for the first time to examine the effect of particle shape.