Study of wall boundary condition in numerical simulations of bubbling fluidized beds

The influence of the solid-phase wall boundary condition was investigated in Eulerian-Eulerian numerical simulations of a bubbling fluidized bed. Parametric studies of the particle-wall restitution coefficient and specularity coefficient were performed to evaluate their impact on the predicted flow hydrodynamics in terms of bed expansion, local voidage, and solid velocity. Both two- and three-dimensional simulations were conducted and compared with available experimental data on solid velocity and bubble properties. It is found that the wall effect plays an important role in CFD models. Such factors as the voidage at the bubble boundary, averaging method, and minimum bubble size also influence the mean bubble diameter.