Shape oscillation of bubbles in the acoustic field
The authors focus on dynamics of multiple air bubbles exposed to ultrasonic wave while ascending in water. The bubbles are injected into the pool filled with water from a vertical capillary tube, and then the ultrasonic wave of 20 kHz is applied from above toward the bubbles. Volume and shape oscillations of the bubbles are captured by a high-speed camera at frame rates up to 84000 fps with a back-lighting system. In the present study the authors pay their special attention to the shape oscillation and the transition from the volume to the shape oscillations of the bubble. Correlation between the bubble size and the most favorable mode number of the shape oscillation is indicated. In addition, the mechanism of the excitation of the shape oscillation is introduced in this fluid dynamics video.
bubble; shap oscillation