A novel hybrid CFD-DEM method for high-fidelity multi-resolution modelling of cross-scale particulate flow

Cross-scale polydisperse particulate-fluid flows are widely practised yet their multi-resolution simulations are not achieved due to the lack of reliable numerical methods. In this work, a novel so-called hybrid CFD-DEM model is developed for the high-fidelity multi-resolution simulations of cross-scale polydisperse particulate-fluid flow systems, for the first time featuring no limit on the grid size to particle diameter ratio (lm/dp). The hybrid CFDDEM method collaboratively considers the fluid-coarse particles interaction (lm/dp < 0.1), fluid-medium particles interaction (0.1 < lm/dp < 3), and fluid-fine particles interaction (lm/dp > 3) by means of the FD (fictitious domain)-based resolved method, semi-resolved method, and unresolved method, respectively. Three typical polydisperse particulate-fluid flow scenarios are simulated for model validation and effectiveness demonstration, i.e., sedimentation of single particle in liquid; drafting, kissing, and tumbling (DKT) process of two particles; and the migration of fine glass particles through the pores of the coarse particles. The results confirm the ability of the hybrid CFD-DEM model of capturing both the detailed flow fields of fluid and particles and particle-fluid interactions in the particulate-fluid flow with a cross-scale size distribution. Moreover, the hybrid CFD-DEM model shows excellent capability in mesh convergence, wide applicability, and high accuracy. It provides a promising tool for the modelling of many cross-scale particulate-fluid flow systems.