A dynamic approach to model subgrid scale cavitation inception

The conditions that initiate cavitation are of significant interest. Accurate estimation of inception is crucial to avert the negative consequences of cavitation, such as noise and vibration. Modeling cavitation inception has specific challenges due to the very small spatial and temporal resolution required. Simulations at coarser resolution do not capture the low pressures that initiate cavitation. We present a dynamic cavitation inception LES model that involves a subgrid-scale cavitation model and a dynamic LES approach that incorporates the subgrid kinetic energy and dynamic variation of local nuclei distribution. The model is applied to a flow where a pair of hydrofoils in a high-velocity water tunnel generates two vortices of unequal strength that interact with each other in the downstream flow. Here, cavitation initiates as a result of vortex stretching and a consequent pressure drop. This flow requires very fine grid resolution to capture these low-pressure sites; however, the inception model is shown to accurately model this behavior even with a sufficiently coarser grid resolution. We studied the flow at three Reynolds numbers- 1.2x10⁶, 1.7x10⁶, and 2.5x10⁶ — at several angles of attack. The predicted inception pressure and its location are compared to experimental results and finer grid simulations.