On the interaction of two cavitation bubbles produced at different times: A jet from the primary bubble

The liquid jet formation upon the collapse of two interacting cavitation bubbles is a physics-rich complex problem, which has possible implications such as the membrane sonoporation. In this paper, we employed both experiment and numerical simulations to study the jet behavior in a bubble, which is affected by another one introduced at various time delays. We provided the regime diagram, which shows the transition of the jet direction as a function of time delay and distance between bubbles. The maximum velocity of the jet in the primary bubble was investigated. The highest velocity was achieved when the primary bubble split into two parts upon collapse. It was found that a high curvature on the rim of the collapsing primary bubble causes the lateral pinch-off, leading to the formation of a fast and thin vertical jet approaching the secondary bubble. The results would help design an effective sonoporation system. The physics depicted in this manuscript might also contribute to the deeper understanding of the jet in a bubble interacting with not only another bubble but also other boundaries.