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

Published online by Cambridge University Press:  29 April 2026

Jianlin Huang
Affiliation:
Key Laboratory for Mechanics in Fluid Solid Coupling Systems, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, PR China School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, PR China
Guanghang Wang
Affiliation:
Beijing Institute of Astronautical Systems Engineering, Beijing 100076, PR China
Tianqing You
Affiliation:
Beijing Institute of Astronautical Systems Engineering, Beijing 100076, PR China
Guangyi Song
Affiliation:
Key Laboratory for Mechanics in Fluid Solid Coupling Systems, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, PR China School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, PR China
Jingzhu Wang*
Affiliation:
Key Laboratory for Mechanics in Fluid Solid Coupling Systems, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, PR China School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, PR China
Yiwei Wang*
Affiliation:
Key Laboratory for Mechanics in Fluid Solid Coupling Systems, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, PR China School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, PR China School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, PR China
*
Corresponding authors: Jingzhu Wang, wangjingzhu@imech.ac.cn; Yiwei Wang, wangyw@imech.ac.cn
Corresponding authors: Jingzhu Wang, wangjingzhu@imech.ac.cn; Yiwei Wang, wangyw@imech.ac.cn

Abstract

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.

Information

Type
JFM Rapids
Copyright
© The Author(s), 2026. Published by Cambridge University Press
Figure 0

Figure 1. Schematic diagram of three patterns of bubble dynamics near a water surface. Complete ventilation is marked by a bullet-jet shape of a bubble in (a); partial ventilation by a non-transparent bubble interior in (b); and non-ventilation corresponds to a toroidal collapse in (c).

Figure 1

Figure 2. Variations of the radius and pressure of the bubble. During the accelerated expansion stage (red regime), the higher internal pressure drives the interface outward, generating perturbations on the bubble wall. In contrast, during the decelerated expansion and contraction stages (green regime), the external pressure exceeds the internal pressure, causing inward acceleration of the interface and leading to perturbations on the liquid surface. Parameter $p^*=\Delta p/p_{\infty }$ represents the dimensionless pressure difference between the inside and outside of the bubble, where $p_{\infty }$ is the atmospheric pressure. Times $T_1$ and $T_2$ are the times when $p^*=0$.

Figure 2

Figure 3. (a) Schematic of experimental set-up. Experimental observations of bubble dynamics near a liquid surface with a laser energy of 190 mJ: (b) non-ventilation at $\gamma =0.40$ and $25\nu _w$, (c) partial ventilation at $\gamma =0.40$ and $\nu _w$ and (d) complete ventilation at $\gamma =0.10$ and $25\nu _w$. A laser beam was emitted by a pulsed laser (Nd:YAG, $\boldsymbol{\nabla }=1064$ nm, with 10 ns pulse width; Spectra-Physics Ltd, USA) and focused through a parabolic mirror. A high-speed camera (V2512, Phantom Co. Ltd, USA) was used to record the bubble dynamics with an LED light source. The sampling frequency of the high-speed camera was $10^{5}$ frames per second, and the exposure time was 300 ns.

Figure 3

Figure 4. Regime map of the ventilation patterns at dimensionless stand-off parameter $\gamma$ versus Reynolds number $\textit{Re}$. Complete, partial and non-ventilation regimes are denoted by blue, orange and green symbols, respectively. Different symbol shapes denote different laser energies, shown in the legend. The theoretical boundaries are indicated by two lines: line 1 between the complete and partial ventilation regimes, and line 2 between the partial and non-ventilation regimes.

Figure 4

Figure 5. Bubble dynamics near a liquid surface at $\gamma =0.30$ and different viscosities $v_l$: (a) partial ventilation at $\nu_l=1\nu _w$, (b) partial ventilation at $\nu_l=10\nu _w$ and (c) partial ventilation at $\nu_l=20\nu _w$. Here, the time when the ventilation occurs ($t_v$) is defined as the time just before the occurrence of white spots on the bubble wall.

Figure 5

Figure 6. Dimensionless ventilation time $t_v^*$ as a function of $\gamma ^*$ for various $\gamma$ and viscosity $\nu _l$. Here, $\gamma ^*=C \ln(\gamma R_{\textit{max}}/\eta _0)\nu _l^{1/3}-\gamma _0^*$. The slope of the function is 20, as indicated at the upper left corner. Different symbols represent the cases at different viscosities.

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