Impact of impeller modelling approaches on SBES simulations of flow and residence time in a draft tube reactor

[Display omitted] •Mean and fluctuating velocities and exit residence time investigated with CFD.•Stress Blended Eddy Simulation (SBES) turbulence model employed.•Momentum source, MRF and sliding mesh approaches give similar results.•Results are in close agreement with experimental data.•SBES model found to work well in a complex internal flow geometry with an impeller. Predictions for flow and residence time in a draft tube reactor were investigated using momentum source, Multiple Reference Frame (MRF) and sliding mesh approaches together with the Stress Blended Eddy Simulation (SBES) turbulence model. Predictions of mean and fluctuating velocities in the annulus, and the exit residence time distribution, are found to be similar and in close agreement with experimental data with all impeller modelling approaches, confirming that the flow in the bulk of the vessel is dominated by the turbulence generated at the draft tube exit and is relatively insensitive to the small-scale turbulence generated by the impeller. On consideration of both accuracy and computational cost, momentum source and MRF approaches offer significant advantages for industrial simulation in this geometry. The SBES model is found to work well in a complex internal flow geometry with an impeller, negating the need for simplifications like zonal LES approaches.