INVESTIGATION OF BUBBLE-BUBBLE INTERACTION EFFECT DURING THE COLLAPSE OF MULTI-BUBBLE SYSTEM

The collapse stage of 3D bubbles in higher surrounding pressure is studied using direct numerical simulation based on the volume of fluid (VOF) method. The numerical results show that the collapse of central bubble in multi-bubble system is different from single bubble collapse significantly, which contains delay stage and acceleration stage. Increasing the number of neighboring bubbles or decreasing the distance between bubbles leads to a longer collapse time and a higher pressure peak of central bubble. According to theoretical analysis, the bubble's radial motion is driven not only by the liquid pressure in the far field but also by the pressures emitted from the neighboring bubbles. The pressures from the neighboring bubbles first decrease and then increase. This leads to the delay and acceleration characteristics of central bubbles.