Measurement and CFD prediction of velocity and concentration profiles in a decelerated gas–solids flow

A CFD program (Fluent, v. 4.4.8) is applied to the simulation of an upstream gas–solids flow in pipes and diffusers using the Lagrangian approach for calculating the dispersed phase. The quantities investigated are the axial particle velocity and the solids concentration. The calculated results are compared with measured data using PDA-technique. Good agreement between measurement and calculation is obtained only if in addition to the models available in Fluent, some further important aspects of particle movement are considered. These models have been included via subroutines programmed by the user and concern particle–wall interaction, particle–particle collision and the particle angular velocity. The individual influence of the added models on the investigated quantities is depicted for the pipe flow using constant parameters. Afterwards, the improved version of Fluent is successfully applied to a variation of the solids loading and to the decelerated flow in and behind a diffuser.