Modeling incipient cavitation during vortex-vortex interaction due to Crow instability

Cavitation inception can occur at sites of low pressure such as the cores of vortices. In shear flows with separation, cavitation inception tends to occur in streamwise weaker vortical structures compared to the stronger spanwise vortical structures. The prevailing theory suggests that the strong spanwise vortices extend the weaker streamwise vortices, resulting in a significant reduction of pressure within the cores of these weaker vortices, leading to inception. This paper presents a numerical investigation into this phenomenon using Large Eddy Simulation (LES) and subgrid scale (SGS) cavitation inception modeling techniques on a pair of vortices generated by two hydrofoils in a high-velocity water tunnel at two Reynolds numbers of 1.2x10⁶ and 1.7x10⁶. Our simulation captures the intricate interplay between the vortices and reduction of pressure within the secondary vortex cores as a result of its stretching. Additionally, the SGS inception model complements LES with modeling the behavior of dispersed nuclei within the flow reacting to the low pressures and estimates cavitation inception within secondary cores at resolved local pressure ~40 kPa higher than the vapor pressure. The results are in good agreement with the experiments both in terms of inception pressure and its location.