The flow behavior of particles in a two-dimensional riser was modeled with the combination of the discrete element method (DEM) and computational fluid dynamics(CFD).Gas turbulence was modeled by large eddy simulation (LES)

and DEM was used to model the collision of particles. A transport energy weighted averaging approach was proposed to coupling the gas phase in the Euler coordinate with the particles in the Lagrange coordinate on the basis of the balance of the transport kinetic energy. Simulated results showed that the clusters grew in size and increased in number along the flow direction. A core-annulus flow structure with a dilute phase in the center and a dense phase near the walls was formed in the riser. Simulated results showed the formation and break-up of clusters and the motion of particles in the riser. Simulated results were in agreement with available experimental data. However

the comparison with different models of drag force remained rather limited. More detailed simulations are required to get a more complete validation.