Challenges and issues on the CFD modeling of fluidized beds: A review

Abstract

We first describe the main approaches used to model fluidized suspensions. Focusing on the multifluid approach, we overview the principal averaging techniques that consent to turn granular systems into continua; in particular, we discuss volume, ensemble and time averages. We then use volume averages to derive the Eulerian equations of motion for fluidized suspensions of a finite number of monodisperse particle classes. We introduce the closure problem, and overview some widely adopted closure equations used to express the granular stress and the interaction forces between the phases, giving emphasis to the fluid-particle interaction force, in particular to the buoyancy and drag contributions. We conclude the work by discussing some published CFD simulations of mono and bidisperse fluidized beds, spanning different fluidization regimes and commenting on the insight that these studies provide.