Unsteady prediction of cavitating flow around a three dimensional hydrofoil by using a modified RNG k-ε model

The present paper suggests a modification of the turbulent viscosity model for predicting cavitating flows. It is to improve the two-equation turbulence model, which failed to accurately predict unsteady cloud cavitation due to the turbulent viscosity overestimated. The modification approach is that the cavitating flow depends on the turbulent viscosity in not only the mixture flow field but also the surrounding flow field in the vicinity of the vapor cavity. The turbulent viscosity in the standard RNG k-e turbulence model was modified by the correlation between the cavitation model and the Barotropic equation of state. The unsteady cavitating flow around a 3-D NACA0015 hydrofoil was simulated by using the modified model as well as the standard model. The simulation result for the modified model agreed well with the experimental one. From the numerical result, the effect of the turbulent viscosity on the cavitation simulation and the cavitating flows was discussed. The present work showed that the strong turbulence is mainly produced in the condensation process, and it delays the cavitation inception in the next cycle.