Verification and validation of Delayed Detached Eddy Simulation for cavitating turbulent flow around a hydrofoil and a marine propeller behind the hull

Abstract The Delayed Detached Eddy Simulation (DDES) was used to study unsteady cavitating turbulent flow around a hydrofoil and a highly skewed marine propeller behind a ship hull. The numerical results reproduced the transient cavitating flow around the hydrofoil and marine propeller, which agreed fairly well with the available experimental data. To further evaluate the accuracy of these DDES results quantitatively, the verification and validation methodologies and procedures were firstly applied in DDES model. The modified three-equation method was derived and illustrated to do verification and validation in DDES model. The hydrofoil cavitation simulation results indicated that the unsteady cavitating flow significantly influenced the distribution of the DDES errors. The periodic cavity shedding and large-scale vortex increased the DDES errors with both being the main source of the large errors. Similar verification and validation methodologies and procedures were then used to analyze propeller cavitation. These results showed that the errors in the predicted thrust coefficient were much smaller than the errors in the total cavity volume. Further analyses with different mesh resolutions showed that the finer flow structures were reproduced with better mesh resolution. Two small peaks between the crest and trough on the fluctuating pressure curves were induced in the predictions using Mesh 6 and Mesh 7 due to the area change of the shedding cavity, which indicated that the pressure fluctuations was closely correlated to the cavitation.