Effect of surface protrusions on the formation and evolution of ventilated attached cavities over a curved wall

Abstract

Large-eddy simulations coupled with the Schnerr–Sauer cavitation model were performed in a simplified curved-wall configuration to investigate ventilated cavity formation downstream of a surface protrusion. The numerical method was validated against water-tunnel data, reproducing the observed cavity morphology and predicting mean wall pressures with relative errors of approximately of 2%–13%. The results show that, in the absence of the protrusion, the near-wall gas undergoes only transient attachment, downstream convection, and shedding, and fails to develop into a persistent attached cavity over the simulated interval. In contrast, the protrusion generates a coupled low-pressure, low-velocity, and recirculating region downstream, which promotes the sustained accumulation of the initial gas cluster and the ventilated gas, thereby enabling the formation of a persistent attached cavity over the simulated interval. The ventilation-hole position strongly affected cavity development: the attached-cavity volume increased from 2.10 × 10−2 m3 at D = 0.3 m to a maximum of 2.36 × 10−2 m3 at D = 0.4 m (four times the protrusion height), and then decreased to 1.19 × 10−2 m3 at D = 0.7 m. These findings demonstrate that a properly placed protrusion and ventilation hole can reorganize the local wake to enhance gas entrainment, confinement, and replenishment, providing a practical route for cavitation control over curved leeward surfaces.