Dynamics of the air bubble on the upper surface of a plate: Influences of the cavitation bubble

The interaction of laser-induced cavitation bubbles with air bubbles attached to the upper surface of a horizontal plate was studied with high-speed photography. On the cavitation bubble side, the dimensionless distance parameter, γ=4.5 for vertical jets from cavitation bubbles as proposed in previous research and the dimensionless parameter, γ=5.8 for oblique upward jets have been established. On the attached air bubble side, the relationship between the dimensionless distance parameter, γa and the four types of morphology (Omega, hemisphere, hemisphere to hat with split, and hemisphere to hat without split) of attached air bubbles, as well as the three modes of jets (initial, multiple, and delay), has been demonstrated. The split of the small bubble from the attached bubble is primarily due to the vertical velocity differences brought about by the multiple collapses of cavitation bubbles and the pulsation of attached bubbles. Subsequent studies on the detachment behavior of attached bubbles determined the ideal dimensionless distance, γa=3.4 for detachment. The surface ripples play a dominant role in promoting the detachment of attached bubbles at greater distances.