CFD simulations of bubbling beds of rough spheres

Hydrodynamics of three-dimensional gas–solid bubbling fluidized beds are numerically analyzed. The particle–particle interactions are simulated from the kinetic theory for flow of dense, slightly inelastic, slightly rough sphere proposed by Lun [1991. Kinetic theory for granular flow of dense, slightly inelastic, slightly rough sphere. Journal of Fluid Mechanics 233, 539–559] to account for rough sphere binary collisions and the frictional stress model proposed by Johnson et al. [1990. Frictional–collisional equations of motion for particulate flows and their application to chutes. Journal of Fluid Mechanics 210, 501–535] to consider the frictional contact forces between particles. The present model is evaluated by measured particle distributions and velocities of Yuu et al. [2001. Numerical simulation of air and particle motions in group-B particle turbulent fluidized bed. Powder Technology 118, 32–44] and experimental bed expansion of Taghipour et al. [2005. Experimental and computational study of gas–solid fluidized bed hydrodynamics. Chemical Engineering Science 60, 6857–6867]. Our computed results indicated that the present model gives better agreement with experimental data than the results from original kinetic theory for frictionless slightly inelastic sphere of Ding and Gidaspow [1990. A bubbling fluidization model using kinetic theory of granular flow. A.I.Ch.E. Journal 36, 523–538] with and without solid friction stress model.