Fully-resolved CFD-DEM simulation of newtonian suspension flows

The mixture of fine and coarse particles with the Newtonian underlying fluid forms a suspension
with complicated behaviours. The particle-particle and fluid-particle interactions in these suspensions are still not well studied at different Reynolds numbers. The current study aims to investigate the effect of particle size distribution on interactions. To this end, the immersed boundary method in the CFDEMcoupling package is utilized, in which the OpenFOAM-based finite volume solvers are coupled with a Discrete Element Method code, LIGGGHTS. Some modifications are made to the solver, and the flow over a stationary sphere, as a benchmark case, is considered to evaluate the solver
accuracy. Then, the sedimentation of particles in an unbounded domain is modelled to examine the interactions in a bidisperse suspension compared to a mono-sized flow system. The results show that the hindrance, caused by opposing fluid flow to the particles settling, has different impacts on each size component. In comparison to a suspension with uniform size distribution, the small and large particles in a bidisperse suspension suffer a higher and lower hindrance, respectively. This hindrance effect is intensified as the diameter ratio increases. Furthermore, it is shown that the collision between different size particles in a bidisperse system leads to a momentum transfer between components.