Development of an Unresolved CFD-DEM Method for Interaction Simulations Between Large Particles and Fluids

In recent decades, growing efforts have been devoted to coupling the Computational Fluid Dynamics (CFD) and the Discrete Element Method (DEM), i.e., CFD-DEM coupling methods, to account for particle-fluid interactions. However, it remains a challenging task for the well-known Immersed Boundary Method (IBM) belonging to the resolved CFD-DEM methods to improve the computational efficiency of large particles occupying several fluid cells and to simulate the interactions between irregularly shaped particles and fluids. In this paper, we present a novel unresolved CFD-DEM method to achieve the end. The main idea of the presented method is to split a large particle into multiple small spherical particles without overlapping using the Bonded-Particle Method (BPM), and simulate the particle-fluid interactions based on each small particle in the context of an unresolved CFD-DEM method. We validate the accuracy and efficiency of the novel method by comparing our numerical results of spherical particles in viscous fluids with those calculated using the IBM and existing experimental data. The presented method is further applied to the irregular large particle-fluid interaction problems, and the numerical results demonstrate the capacity of our method in simulating the motions of nonspherical large particles in the fluid.