Gas entrainment from gaseous supercavities: Insight based on numerical simulation

The understanding of the internal gaseous flow of artificially ventilated supercavities is developed using a locally homogenous, multiphase computational fluid dynamics model that is benchmarked using experimental data. The solutions indicate that gas leakage from a ventilated supercavity originates from the gaseous shear layers forming at the gas-water interface. Not only do these observations corroborate previous theory developed for cavities with toroidal closure, they also display evidence that shear-layer mechanisms remain important for cavities in the twin-vortex regime and when interacting with bodies. It is also found that the treatment of turbulence in these shear layers affects the outcome of computational fluid dynamics approaches. Lastly, a semi-empirical model considering these shear layers is proposed. Results from the model indicate an improved prediction capability of the relationship between cavity size and ventilation rate for steady, twin-vortex supercavities.