Comparison between finite volume and lattice-Boltzmann method simulations of gas-fluidised beds: bed expansion and particle–fluid interaction force

Abstract

Lattice-Boltzmann method (LBM) simulations of a gas-fluidised bed have been performed. In contrast to the current state-of-the-art coupled computational fluid dynamics–discrete element method (CFD–DEM) simulations, the LBM does not require a closure relationship for the particle–fluid interaction force. Instead, the particle–fluid interaction can be calculated directly from the detailed flow profile around the particles. Here a comparison is performed between CFD–DEM and LBM simulations of a small fluidised bed. Simulations are performed for two different values of the superficial gas velocity and it is found that the LBM predicts a larger bed expansion for both flowrates. Furthermore the particle–fluid interaction force obtained for LBM simulations is compared to the force which would be predicted by a CFD–DEM model under the same conditions. On average the force predicted by the CFD–DEM closure relationship is found to be significantly smaller than the force obtained from the LBM.