A new numerical model using both Eulerian and Lagrangian coordinates, and taking account of interparticle interactions, has been developed for the study of hydrodynamic aspects of dense particle-laden rise flows. A stochastic particle dispersion model has been incorporated in the original model to describe the gas particle turbulent flows. In addition, the collisional interaction between the particles has been modeled using the kinetic theory of granular flows based on the Chapman-Enskog theory of dense gases. A comparison with the experimental results of Miller and Gidspow (1992) shows reasonably good agreement, The present model may provide a useful approach for predicting the complex hydrodynamic behaviour of fluidized bed systems.