The acoustic radiation of the bubbles is considered in the equation of bubble dynamics, and the forces of interaction between oscillating bubbles are researched theoretically. The numerical results show that there is the attraction interaction between the bubbles with the same size, and the attraction and repulsion appear alternately because the phase of interacting forces vary with time when the two bubbles have different sizes. By high speed photography, the distribution of bubbles is observed in the ultrasonic field caused by the working transducer whose radiation surface is submerged in the tap water. When a local bubble cluster moves to the region where sound pressure is weaker, there is a single bubble escaped continuously from the pit of bubble cluster surface, which presents that bubbles repulse each other in that position. The two bubbles are attractive to each other when their sizes are almost same.

Bubble dynamics; bubble cluster; forces of interaction; high speed photography