When the particle phase is dense, two fluidization regimes can be defined, i.e., homogeneous and bubbling fluidization. In this study, two approaches, i.e., the particle-scale flow analysis and dimensional analysis, were applied to study the mechanism of transition between homogeneous and bubbling fluidization regimes. The fluidization behaviors were simulated using the discrete element method and the computational fluid dynamics (DEM-CFD) coupling model. The findings reveal that the bubbling and homogeneous regimes were almost divided into two separate regions when the lateral force was plotted against the Archimedes number (Ar) and Reynolds number (Re). The boundary plane that separated the homogenous and bubbling regions was expressed as a function of (Re/Ar). Within the Stokes flow region, (Re/Ar) can be expressed by the dimensionless drag force and buoyancy. The results of plotting the dimensionless gravity term against Re revealed that the dimensionless gravity term:  distinguishes between the two states of fluidization.

bubbling fluidization, homogeneous fluidization, non-dimensionalization, dimensionless number, lateral force, aggregate or particulate fluidization.