Experimental Study on Interaction of Multiple Cylindrical Bubbles with Underwater Shock Wave

The present paper reports on an experimental investigation of the behaviors of multiple cylindrical bubbles induced by underwater shock wave. The bubbles are formed in a narrow water chamber by an injection to observe conveniently their internal flow. In this way, the number, size, and position of the bubbles are controlled. As observed by using the schlieren method, cavitation bubbles are produced behind a shear waves followed with expansion regions. The life times of these cavitation bubbles are short so that the motion of the cylindrical bubble is hardly affected. For a single bubble, the liquid jet is formed during the bubble expansion and points towards the propagation direction of shock wave. In the case of the multiple bubbles, the direction of the jet depends on the combination of the shock wave-induced action and interaction forces between the bubbles. Here, the generation of a counter jet is used to determine whether or not the interaction forces work. It is suggested that the strength of the bubble motion is a main factor related to the magnitude of the interaction force besides the inter-bubble space.