Acoustic bubble behavior in a standing wave field

Abstract

This paper focuses on the experimental and numerical studies of acoustic cavitation induced micro bubbles in a standing waveguide filled with water. It is shown that the cylindrical geometry of the system used in this study allows the micro bubbles to self organize into particular patterns. At high pressure amplitudes, the cavitation bubbles tend to aggregate into well known cluster patterns and at relatively low pressure amplitudes, the cavitation micro bubbles aggregate into ring patterns. This study highlights that the shape of these ring patterns is directly related to the Bjerknes force distribution in the resonator. It is also shown both experimentally and numerically that cavitation bubbles may exhibit spiraling behavior around this ring pattern. This spiraling phenomenon is numerically studied and the conditions for which a single cavitation bubble follows an orbital trajectory in the cylindrical waveguide are established, and the influences of the acoustic pressure amplitude and the initial bubble radius are investigated.