A Stokes number-dependent filtered drag model for fluidized gas-particle beds with varying material properties

Abstract

In fluidized bed systems, accurately predicting drag forces is essential for understanding particle-fluid interactions, and the drag force model should be applicable across a wide range of parameters for particles with varying material properties, such as Geldart A, B, and D types. Using fine-grid two-fluid simulation data from periodic sedimentation systems, this study examines the influence of Stokes number St, density ratio DR, dimensionless filter size, and filtered solid volume fraction ${\overline{\varphi }}_s$ on the heterogeneous index $H_d$. For the same St but different DR, $H_d$ decreases as DR increases. Conversely, for the same DR but different St, a critical solid volume fraction ${\overline{\varphi }}_{s,c}$ of approximately 0.32 is observed: when ${\overline{\varphi }}_s<{\overline{\varphi }}_{s,c}$, $H_d$ increases with larger St, while when ${\overline{\varphi }}_s>{\overline{\varphi }}_{s,c}$, $H_d$ increases with smaller St. Furthermore, $H_d$ approaches unity at high St (St > 20,000) for Geldart D particles. Based on these findings, a unified filtered drag model was developed by incorporating St to capture the impact of material properties. The proposed model demonstrates favorable performance in a posteriori tests across various fluidized beds.