VISUALIZATION OF THE FLUID-FLOW FIELD AROUND A LASER-GENERATED OSCILLATING BUBBLE

We report on a new method of visualizing qualitatively a fluid flow fi eld around an oscillating cavitation bubble. The near infrared radiati on of a Q-switched Nd:YAG laser is focused in deionized water and in a solution of copper sulphate for contrast enhancement to generate a ca vitation bubble in free space and in front of a solid boundary. Using high-speed photography and an accurately positioned schlieren knife ed ge we are able to visualize the heated path of the laser beam and the different stages of the oscillating bubble with high spatial resolutio n. For the case of a bubble in free space the marked laser path indica tes radial fluid flow only. For a bubble in front of a solid boundary the marked laser path clearly shows the motion of the fluid through th e bubble during the collapse process. The marked paths are similar to numerically calculated streamline plots. (C) 1997 American Institute o f Physics.