Influence of grid type and turbulence models on the numerical prediction of the flow around marine propellers working in uniform inflow

In this work we analyze the influence of grid type and turbulence model on the numerical prediction of the flow around marine propellers, working in uniform inflow. The study is carried out comparing hexa-structured meshes with hybrid-unstructured meshes using the SST (Shear Stress Transport) turbulence model and the BSL-RSM (Baseline-Reynolds Stress Model) turbulence model. The simulations are carried out with a commercial CFD solver. The numerical results are compared with the available experimental data of two propellers in model scale. The comparison is carried out evaluating the global field values, represented by the thrust and torque coefficients, and also considering some local field values measured in the propeller wake. The computational results suggest that, for the numerical predictions of the propeller open water propulsion characteristics, the hexa-structured and hybrid-unstructured meshes can guarantee similar levels of accuracy. Nevertheless hybrid-unstructured meshes seem to exhibit a more diffusive character than hexa-structured meshes, and thus they are less suited for detailed investigations of the flow field. Finally, the two different turbulence models behave similarly on both types of meshes, with the BSL-RSM turbulence model providing only slightly better predictions than the computationally more economical SST turbulence model.