Scaling law for ventilation of a near-liquid-surface bubble induced by Rayleigh–Taylor instability

Interfacial instability dominates the dynamics as a cavitation bubble oscillates in close proximity to a liquid surface, driving perturbations on both the bubble wall and the liquid surface. The penetration of the liquid layer initiates ventilation, exposing the bubble interior and thereby altering its subsequent dynamics. To quantitatively elucidate the interfacial coupling-induced instability, we develop a theoretical model that couples the perturbation equation with the bubble oscillation equation, considering the liquid viscosity. The model predicts the transition boundaries between ventilation patterns by critical stand-off parameters, which scale exponentially with the liquid viscosity to the −1/3 power. The boundary between complete and partial ventilation regimes shows negligible viscous dependence due to the vanishingly short perturbation growth time. Furthermore, we derive the scaling law of ventilation time, defining it as the instant of perturbation penetration. A series of experiments on bubble oscillation near a liquid surface was conducted, which verified the predictions of the theoretical model. This offers a practical framework for the engineering application of near-surface bubble collapse.