Numerical prediction of steady and unsteady tip vortex cavitation on hydrofoils

The article presents the numerical method for prediction of tip vortex cavitation generated on hydrofoils. This method has been developed in the course of numerical and experimental research described in earlier publications. The objective of the research was to design the optimum discrete grid structure for this specific computational task and to select the best turbulence model for such an application The article includes a short description of the method and a computational example demonstrating its performance. In this example the results of numerical prediction of the cavitating tip vortex obtained from two commercial CFD codes are compared with experimental photographs taken in the cavitation tunnel in the corresponding flow conditions. Altogether nine different flow conditions are tested and analyzed, but only selected results are included. The accuracy of the numerical predictions is discussed and the reasons for minor existing discrepancies are identified. The unsteady tip vortex calculations are also presented, showing the fluctuations of the transverse velocity components predicted for three cross-sections of the cavitating vortex kernel.