Bubble pairs are effective modulators of liquid jets. We investigate the jetting of an air bubble driven by a laser-induced cavitation bubble using high-speed imaging, compressible volume-of-fluid (VoF) simulations and theoretical analysis. Three distinct jet types emerge, depending on the stand-off distance and size ratio between the bubbles. Jet formation proceeds through two stages: an initial shock-induced acceleration followed by flow focusing on the concave liquid–air interface. We derive scaling relations, V₀=1. 1 p₀R₀/ (cRₗ) ( ( (1+) -1) /) ^-1. 6 for the shock-driven stage and Vₘ= (1+ (0. 8-0. 5) ^0. 75) V₀ for the flow focusing stage in the strong jet regime, both of which agree closely with experimental and numerical measurements. Here, V₀ and Vₘ denote the velocity increments associated with shock-wave-induced acceleration and flow focusing stages, respectively. The variables p₀, R₀, , c and Rₗ represent the initial pressure and radius of the cavitation bubble, the fluid density, the speed of sound in the liquid and the maximum volume-equivalent radius of the cavitation bubble, respectively. A (, ) phase diagram delineates the weak, strong and explosive jets, with regime boundaries accurately captured by the theoretically derived transitions.
Liu et al. (Fri,) studied this question.