A Novel Multi-Resolution Hybrid CFD-DEM Method for High-Fidelity Modelling of Cross-Scale Particulate-Fluid 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 (l_m/d_p). The hybrid CFD-DEM method collaboratively considers the fluid-coarse particles interaction (l_m/d_p <0.1), fluid-medium particles interaction (0.1< l_m/d_p < 3), and fluid-fine particles interaction (l_m/d_p >3) by means of the FD (fictitious domain)-based resolved method, semi-resolved method, and unresolved method, respectively. The model effectiveness and accuracy are validated by the three typical polydisperse particulate-fluid flow scenarios. 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. This work provides a promising tool for the modelling of many cross-scale particulate-fluid flow systems.