Implementation of a transpiration velocity based cavitation model within a RANSE solver

A transpiration velocity based partial sheet cavitation model has previously been successfully validated when implemented within potential flow codes. The model is independent from any solver and permits to estimate the cavity length based on the subcavitating pressure distribution. This paper presents its implementation within a Reynolds Averaged Navier-Stokes Equations solver. In order to compare the results of the implementation, experimental measurements on a 2D hydrofoil and potential flow code results are used. Several stages are covered. First the geometries of the cavitation sheets computed with the potential flow code are imposed with a slippery boundary condition on its surface into the RANSE simulation. The results obtained are in very good agreement with the previous validated results. In the second stage, the Volume of Fluid module is activated and water vapour is ejected from the foil surface and the transpiration velocities are computed with the potential flow code. The results are similar but the length of the cavitation closure is much shorter. Finally, the model is fully implemented within the RANSE solver. The transpiration velocities are computed using the model from the subcavitating pressure distribution. They are then applied on the foil surface as water vapour. The results are quasi-identical to the results obtained when the transpiration velocities are taken from the potential flow code. The paper proves the feasibility of modelling the cavitation sheet using transpiration velocities and VOF within a RANSE solver.