Microbubble-induced instability in free-falling water jets

The breakup dynamics of liquid jets at low Reynolds numbers have been well characterized in single-phase systems based on classical Rayleigh and Weber models. However, the influence of microbubbles in, multiphase jets has received limited attention, despite their increasing use in industrial applications such as precision cleaning. This study explores how varying microbubble void fractions influence the breakup length of vertically free-falling water jets governed by Rayleigh-type instability. Surfactant and microbubbles altered fluid properties, and even low void fractions significantly shortened the breakup length and led to earlier jet disintegration. Microbubbles consistently promoted jet instability by reducing inertial forces and disturbing internal flow structures. Particle image velocimetry (PIV) revealed altered velocity profiles and higher flow instabilities in bubble-laden jets. These findings offer deeper insight into multiphase jet behavior and provide guidance for optimizing microbubble-based fluid systems.