Multi-scale analysis on particle-phase stresses of coarse particles in bubbling fluidized beds

Despite the restless efforts devoted to the hydrodynamics of bubbling fluidized beds, the particle-phase stress, which is one of the critical issues in modeling bubbling fluidized beds by the Eulerian approach, is not well understood. To address this problem, a mathematical model is developed to describe the kinetic properties of coarse particles, such as granular temperature and granular pressure, based on a multi-scale analysis of particle velocity fluctuation. Contributions from both high-frequency particle-scale fluctuations and low-frequency bubble-induced fluctuations are considered. It is proven to agree well with experimental data available up to date from bubbling fluidized beds for Geldart B and D particles.