Analysis of suppressive effect of large bubbles on oscillation of cavitation bubble in cavitation field

Abstract

In this work, the interaction among multiple bubbles in a cavitation field is investigated by combining the experimental observation of small bubbles hovering around large bubbles. A model composed of three bubbles is developed, and the dynamic behavior of cavitation bubble is analyzed. By considering the time delay effect of the interaction among bubbles and the nonspherical oscillation of large bubbles, the modified bubble dynamic equations are obtained. Numerical results show that the nonspherical effect of large bubbles has little effect on the oscillation of cavitation bubble. The suppressive effect of large bubble on cavitation bubble is closely related to the radius of the large bubble. The larger the size of the large bubble, the stronger the suppression is. When the size of large bubble approaches to the resonant radius, the oscillation of cavitation bubble presents coupled resonance response, and the maximum expansion radius of bubble shows a resonance peak. The distribution of the secondary Bjerknes force versus bubble radius and the separation distance is strongly influenced by driving frequencies or sound pressure. When the large bubble is on the order of submillimeter, the intensity of the secondary Bjerknes force and the acoustic response mode are different due to the different intensity of the nonlinear response of the cavitation bubble. As the distance decreases, when the acoustic pressure increases to a certain value, the secondary Bjerknes force on the cavitation bubble decreases due to abnormal acoustic absorption. The secondary Bjerknes force on cavitation bubble is likely to be repulsive at different separation distances. The theoretical results accord well with experimental phenomenon.