Numerical investigation of the cavitating flow structure with special emphasis on the vortex identification method

The three kinds of vortex identification methods, namely, ωz criterion, Q criterion and ω method, are then employed to investigate the physical interactions between the cavitation and vortex dynamics around two-dimensional Clark-Y hydrofoil. The results show that compared to the ωz and Q criterion, the ω method can capture the vortex structures with both strong and weak vortices, especially for the weak vortices located in the boundary of the cavity and the back region of the re-entrant flow. A proper value of in ω method based on the previous studies is then suggested to avoid the pseudo-vortex structure in cavitating flow field due to division by zero. The modified ω method with a proper is then applied to analyze the details of vortical structures in the growth of attached cavity, the re-entrant flow development stage and the cloud cavity shedding stage. The results show that the vortical structures are captured in the boundary and rear region of the attached cavity, the intensity and complexity of strong vortices in the rear boundary region of re-entrant flow increased with its development, and the strength and area of vortical structures at the trailing edge of hydrofoil increased with propulsion of cloud cavity before it sheds completely.