S0507-1-4 Multibubble cavitation inception

The dynamics of multiple bubbles under negative pressure is studied numerically and theoretically to show that cavitation inception in multibubble cases can have several patterns different from that in single-bubble cases. Using a multibubble model based on the Rayleigh-Plesset equation, we first show that the suppression of explosive expansion of a bubble due to the interaction of non-identical bubbles, which we reported recently, can take place not only in liquid mercury but also in water. We then found that a relatively large bubble can significantly decrease the cavitation threshold pressure of a neighboring small bubble. By examining the transition region where the dynamics of the suppressed bubble changes dramatically as the inter-bubble distance changes, we determined that the explosive expansion of a bubble can be interrupted and turn into collapse even though the far-field liquid pressure exceeds the bubble's cavitation threshold pressure. Numerical results suggest that the interruption of expansion occurs when the bubble radius is exceeded by the instantaneous unstable equilibrium radius of the bubble. The present findings would be helpful in understanding the complex behavior of cavitation bubbles in practical applications where many cavitation nuclei interact with each other.