Turbulent cavitating flows under periodic inflow perturbations

This work is devoted to numerical studies of transient evolution characteristics and drag reduction mechanisms of ventilated cavitating flow over an underwater axisymmetric vehicle under periodic flow disturbances. The unsteady Reynolds-averaged Navier–Stokes approach is adopted along with the volume-of-fluid method and the shear-stress transport k−ω turbulence model. The results show that the numerical method can accurately predict the cavity shedding dynamics and internal pressure fluctuations at the cavity development stage. Under various inflow conditions, the pressure fluctuations are consistent with the transient cavity behaviors in the spectral–temporal domain. The increased amplitude and frequency of fluctuating inflow intensify the randomness of cavity shedding, leading to higher drag on the underwater vehicle. Additionally, the new Ω identification method reveals the topological features of multiscale vortex structures in the cavity shedding process. The strength and scale of the vortices vary significantly with the vehicle's angle of attack, which is primarily governed by vortex stretching and baroclinic torque terms. Although the drag reduction rate decreases with increasing angle of attack, the novel double-ventilated ring configuration effectively suppresses cavity shedding and substantially enhances drag reduction efficiency. These findings offer valuable insights into the design and control of ventilated cavitating flows around underwater vehicles.