Numerical study of the pressure wave-induced shedding mechanism in the cavitating flow around an axisymmetric projectile via a compressible multiphase solver

The periodic shedding of cloud cavitation has been previously assumed to be induced primarily by re-entrant jet based on considerable experimental and numerical studies. However, different shedding mechanisms, including that induced by pressure waves, have recently regained research interest. To conduct a corresponding numerical investigation, the cavitating flow around an axisymmetric projectile is studied using a user-designed solver that considers the compressibility of the three phases and phase change within the OpenFOAM (R) framework. Results are compared with those of an experimental study based on Split Hopkinson Pressure Bar (SHPB) technology with high-speed photography. Good agreement on cavity morphology is confirmed between the results. During the first period, a typical re-entrant jet-induced shedding mechanism is observed as the re-entrant jet front coincides with cavity closure. By contrast, their evident separation is noted in the second period, and cavity closure is located in a counterflow area caused by the impact of pressure waves that are radiated by the collapse of a shedding cavity and propagate in liquid water. This observation is never predicted by an incompressible solver used for comparison, thereby indicating that the existence of a different shedding mechanism is highly relevant to compressibility.