48 / 2025-04-28 13:56:49

The emulsification mechanism of W/O droplets near solid boundaries induced by bubble pulsations

Bubble dynamics,Cavitation,Droplet

Boundary effects lead to a jet and migration phenomena during cavitation bubble collapse.This transient non-linear hydrodynamic phenomenon has significant applications in ultrasonic emulsification.The interaction between bubbles and dispersed-phase droplets is a crucial mechanical mechanism in the emulsification process. Although substantial research has been conducted on the interactions between bubbles and droplets in infinite domains, the effect of the rigid wall on the efficiency of emulsion droplet formation remains unclear.Therefore, laser-induced cavitation bubble experiments were conducted to nucleate bubbles within oil-in-water droplets near rigid walls, investigating the strong nonlinear coupling effects among the bubble, droplet, and rigid wall.Through high-speed imaging, we identified three multiphase mixing modes, with the vortex ring motion generated by the impact of the bubble jet being the dominant factor.Furthermore, the evolution of bubbles and droplets was simulated using a finite volume method.The numerical results reveal the mechanical mechanisms of vortex-ring-induced emulsification.This study provides new insights for elucidating the intrinsic mechanisms governing the dynamic evolution patterns of disperse-phase droplets during emulsification processes.