Study on a semi-resolved CFD-DEM method for rod-like particles in a gas-solid fluidized bed

Abstract

Based on a semi-resolved CFD-DEM coupling method, this study proposed a method that uses the minimum distance between the fluid grid and the particle boundary as a reference value to determine the degree of influence of the target fluid grid on the particle's drag force. A fluidized bed of rod-like particles was chosen as a typical case to investigate the effect of different fluid grid scales on various fluidized bed characteristic parameters. The calculation performance of the semi-resolved and unresolved CFD-DEM coupling algorithm on key fluidized bed characteristic parameters such as average pressure drop, particle frequency distribution with bed height, and particle orientation distribution were compared. It was found that the semi-resolved CFD-DEM coupling algorithm gradually obtained results with higher consistency with decreasing fluid grid scale for key parameters such as particle frequency distribution with bed height, particle orientation distribution, and time-history mixing index, exhibiting a phenomenon similar to grid independence in fluid simulation. By comparing with experimental results, it was verified that the semi-resolved CFD-DEM coupling algorithm can be applied to simulate multi-granular gas-solid systems with fluid grid scales equivalent to particle scales. This algorithm solves the limitation of fluid grid scale in the unresolved CFD-DEM coupling framework and improves the grid adaptability of the CFD-DEM coupling simulation algorithm.