A dual-grid approach to speed up large-scale CFD-DEM simulations

•A new dual-grid approach is developed to significantly accelerate CFD–DEM simulations.•Fine grid is used to solve the fluid velocity and particle–fluid interaction for accuracy.•Coarse grid is used to solve the pressure for mass conservation and reducing computation. With the development of heterogeneous computing, the coupling of discrete element method (DEM) and computational fluid dynamics (CFD) has become an effective approach to simulate large-scale particle–fluid systems. With various models and algorithms accelerating the DEM part significantly, the CFD part becomes an efficiency bottleneck, especially for large-scale simulations. A dual-grid approach is proposed to address this issue. On the fine grid, the fluid velocity and particle–fluid interaction are solved without compromising accuracy in capturing flow details, and the pressure is solved on the coarse grid to ensure mass conservation to boost the CFD part. This approach is validated by simulating several gas–solid fluidized beds, demonstrating a performance speedup of 2.6 for low workload and 10.1 for high workload.