Toward the influence of fluid convection on filtered drag force in fluidized gas-particle flows

Mesoscale drag modeling for gas-solid flows is typically based on fully-periodic systems where fluid convection is insignificant. This study examines a series of 2D sudden-expanded fluidized beds (SEFBs) to investigate the effects of fluid convection on the filtered drag force. A priori analysis indicates that the volumetric force induced by convection has a notable impact on the filtered drag force, and correlations of drag force using traditional markers (such as solid volume fraction, slip velocity, and filter size) fail to provide accurate predictions. In contrast, the gas-phase pressure gradient shows a good correlation with drag force when strong convection is present. Posterior tests in the SEFBs with several existing drag models reveal that the predictive capacity of drag models constructed with traditional markers declines under conditions with strong convection, whereas the drag model incorporating the gas-phase pressure gradient still performs well.