A dual–grid approach for <scp>CFD</scp>–<scp>DEM</scp> simulation of gas–solid heat transfer

Abstract Gas–solid fluidized beds are widely used in industrial processes. Accurate and efficient simulations of the gas–solid flow dynamics and transfer are crucial for improving the design, scale–up, and optimization of the reactors. For this purpose, a dual–grid computational fluid dynamics and discrete element method (CFD–DEM) approach is developed to study the gas–solid heat transfer. The proposed approach uses both coarse and fine grids, where the gas velocity and pressure on the coarse grid are solved by the complete Navier–Stokes equations, while the gas velocity on the fine grid is predicted by solving the simplified Navier–Stokes equations. The predicted mass flux at the face center is then corrected by solving the velocity potential equation, and the energy conservation equation is solved on the fine grid. Results show that the proposed dual–grid approach can produce comparable results with the fine–grid CFD–DEM simulations and achieve at most 65.1 times speedup.