Fine grid numerical simulations have been performed on a periodic section of a riser using the kinetic theory of granular flows (KTGF) approach. A substantial number of different model settings and constants were evaluated in order to assess their importance on the overall hydrodynamics occurring in the riser. Special care was taken to ensure that sufficient spatial and temporal resolution was implemented so that the discretization error would be minimal. The description of the shear at the walls, the particle-particle restitution coefficient and the models selected for the solids viscosity and the diffusion term in the granular temperature equation were found to be the most influential factors. Model selection for the frictional viscosity and solids pressure also had a marginally significant influence. It was found that the effects of particle-wall restitution coefficient, drag formulation, bulk viscosity and gas phase turbulence were negligible. The final combination of model settings produced results that compare well with published experiments. (C) 2010 Elsevier B.V. All rights reserved.