Bubble-induced mesoscale drag model for the simulation of gas-solid bubbling fluidization

Abstract

Abstract The application of homogeneous drag models using coarse grid simulation with the two-fluid model have some limitations in the prediction of hydrodynamic behaviors in gas–solid bubbling fluidization owing to the negligence of bubble mesoscale structures. To characterize the mesoscale effect caused by bubbles, a multi-scale decomposition strategy at the bubble boundary is implemented and a bubble-induced drag model is developed via an introduction of local solids holdup gradient to consider the impact of the heterogeneous structures. The modified model is verified by the direct numerical simulation results and applied to the simulation of a freely bubbling fluidized bed. The results demonstrate that the present model can predict the bubble behaviors more accurately compared to the homogeneous drag model.