The oscillations of non-spherical bubbles in liquid.

In this paper, the interaction between non-spherical bubbles is studied using a high-speed camera, and the effects of the interaction on the temperature within the bubble and the velocity of the surrounding fluid are theoretically investigated. It is found that the mean radius and the mean wall velocity of the middle bubble in three-bubble system are slightly greater than those in two-bubble system when the initial parameters are consistent. The acoustic response of the middle bubble presented a leftward shift of resonance peak and an increase of resonance peaks with increasing sound pressure. Two patterns of interactions were found in the three-bubble system: steady oscillations with slight non-spherical shape deformation, and a strong coupled state that tends to coalesce. In both patterns, the largest bubble should impose more constraints on the middle bubble, and the middle bubble was observed to be ejected towards the largest. The interacting pattern of bubbles depends on many factors, such as bubble spacing, initial radii of bubbles, acoustic frequency and intensity, which also affect the shape deformation of bubbles. Non-spherical shape deformation decreases the internal gas temperature and disturbs the flow field distribution, all of which are close to cavitation activities. Predictions of the three-bubble model are in good agreement with experimental observations, and can be used to explain bubble behaviors in chained multi-bubble systems in inertial cavitation field.