Gas-particle flow behavior in a cylindrical spouted bed and a three dimensional spout-fluid bed of spherical particles was simulated using the Eulerian-Eulerian two-fluid modeling approach, incorporating a kinetic-frictional constitutive model for dense assemblies of the particulate solid. The interaction between gas and particles was modeled using the Gidaspow drag model and the predicted hydrodynamic characteristics are compared with published experimental data. The overall flow patterns within the cylindrical spouted bed were predicted well by the model, i.e. a stable spout region, a fountain region and an annular downeomer region were correctly predicted by the model. The flow instabilities which develop in the spout-fluid bed are along with discussion of the mechanisms leading to instabilities. Bubble formation and motion of the bubbles inside the spout-fluid bed are also described. Such predictions can provide important information on the flow field within the spouted beds for process design and scale-up. (c) 2007 Elsevier B.V. All rights reserved.