Temporal Evolution of Laser-Induced Bubbles and Shock Waves Near a Rigid Boundary
X-M. Liu, B-B. Li, J. He, W-H. Li and J-Y. Zhao
Shock wave emission and cavitation bubble dynamics after optical breakdown in water with Nd:YAG laser is investigated by a fibre optic diagnostic technique based on an optical beam deflection (OBD). The detachment properties of the shock wave and bubble wall are also performed by a finite volume method (FVM) and the volume of fluid method. By the sequence of experimental waveforms detected at different distances, the attenuation properties of shock waves are obtained. They show that a shock wave and a cavitation bubble coexist during the early stages of optodynamic phenomena, and therefore they cannot be distinguished. With an increase in distance, the shock front rapidly detaches from the bubble wall, and the valley between the plasma shock wave and bubble wall become larger. Furthermore, the bubble collapse-induced shock wave is also gradually detached from the contracting bubble walls, and the interval between shock wave and bubble also becomes larger with increasing time. The evolution and propagation characteristics of the shock wave and bubble give valuable insight into the dynamic flow of laser induced phase explosions in materials and gases.
Keywords: Nd:YAG laser, shock wave, cavitation bubble, finite volume method (FVM), detachment, optical beam deflection (OBD)