A steady-state EMMS drag model for fluidized beds

Abstract

Mesoscale structures exist inherently in fluidized beds and hence should be taken into account in the constitutive modeling of the drag force. To account for mesoscale effects, previous efforts have been paid on extending the steady-state Energy-Minimization Multi-Scale (EMMS) model to the sub-grid level by introducing acceleration terms into the force balance equations. The EMMS drag models thereof were normally confined into specific flow regimes. In this work, the definition of the heterogeneity index was refined by incorporating the steady-state force balance between the drag and buoyed weight. A simple derivation thereof agrees well with the filtered drag model. Based on such analysis, we proposed a new drag model by solving the steady-state EMMS equations. As a preliminary validation, this new drag was found to allow successful CFD simulation of flow behavior of fluidized beds covering a broad range of flow regimes.