Surface oscillations and fragmentation of bubbles in an acoustic field

Abstract

Surface oscillations and fragmentation of individual bubbles confined in a thin liquid layer driven by an acoustic field have been investigated via high speed photography. It is show that under the experimental conditions, above a critical size threshold, the observed bubbles exhibit surface modes (standing Faraday waves on the bubble surface). Furthermore, With the increase of acoustic pressure, the amplitude of surface oscillation increases. Above a critical threshold, Jet formation and droplet ejection tear the bubble to pieces. The image analysis shows that the wavelength of Faraday wave on the bubble surface is independent of the acoustic pressure and the bubble radius, while the order of the surface mode is approximately proportional to the bubble radius. Based on a quasi-two-dimensional approximation, a physical model describing the surface oscillation of the bubble in the thin liquid layer is proposed. The mechanism of bubble splitting and its relationship with the acoustic parameters are analyzed...