Radial Instabilities of a Pulsating Air Bubble in Water

Recently, several theoretical studies have been originated concerning the spherical stability of a pulsating air bubble in water. In this study, a light scattering technique was utilized to record in real-time the motion of the bubble surface. The main objective was to experimentally determine the shape oscillation threshold of an acoustically driven air bubble in water. These thresholds were defined as the minimum pressure necessary to drive a bubble, at a particular radius, into non-radial motion. Results of this study show a marked improvement over previous experiments in detecting the radial instabilities resulting in shape oscillation. Further, by using a numerical integration technique applied to a simplified theory, the experimental shape oscillation thresholds were predicted quite well. Surface wave threshold phenomena; Equations of motion; Numerical integration; Interfacial tension; Laser radiation pressure effects; Physical acoustics; Mie scattering; Radial instability; Nonlinear dynamics; Shape oscillations; Dissertations.