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A new numerical model using both Eulerian and Lagrangian coordinates, and taking account of interparticle interactiorrs, 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 (1 992) shows reasonably good agreement. The present model may provide a useful approach for predicting the complex hydrodynamic behaviour of fluidized bed systems.Un nouveau modele numerique utilisant a la fois des coordonnees euleriennes et lagrangiennes et tenant compte des interactions entre les particules a ete mis au point pour I'etude des aspects hydrodynamiques d'ecoulements ascendants charges de particules denses. Un modkle de dispersion de particules stochastique est introduit au modele original afin de decrire les ecoulements turbulents gaz-particules. En outre, I'interaction collisionnelle entre les particules est modelisee a I'aide de la theorie cinetique des ecoulements granulaires reposant sur la theorie des gaz denses de Chapman-Enskog. La comparaison avec les resultats experimentaux de Miller et Gidsprow (1 992) montre un accord raisonnablement bon. Le modele present peut fournier une approche utile pour la prediction du comportement hydrodynamique complexe des systemes de lits fluidises.Keywords: EuleriadLagrangian approach, interparticle collision, dense particle-laden rise flows. ide application of gas particle flows in the field of W power station equipment, such as fluidized-bed boilers, tangentially fired boilers or front-wall-fired boilers, has led to important efforts in the theoretical modeling of two-phase flows. There has been an ever-increasing demand for more precise simulation for two-phase flows, especially dense fluid-particle flows.Both the EuleriadEulerian and EuleriadLagrangian approaches have advantages and disadvantages. In particular, the EulerianLagrangian approach can provide more detailed information on the dispersed phase of different particle sizes, but may be time-consuming when applied to relatively dense particulate two-phase flows (Andrews, 1996). The EulerianiEulerian approach has the advantages of being easily solved and understood, and is thought to be especially accurate when applied to dense two-phase flows, but will be found to be unsuitable for two-phase flow of various particle characteristics, such as size and density.Turbulent dispersion of particles and interparticle collisions are of critical importance for the accurate prediction of two-phase flows. There has been intensive research work done in recent years. Fan et al. (1997) has introduced a new stochastic particle dispersion model into a Euleriad Lagrangian method for dilute two-phase jet flows. Modeling of interparticle colli...