Effect Of Liquid Parameters On Expansion And Collapse Of Laser-induced Cavitation Bubble

In this paper, the laser-induced bubble dynamics and bubble-collapse-induced liquid-jet are systemically investigated by numerical, theoretic and experimental analyses. Meanwhile, the effect of liquid viscosity, surface tension, temperature, gas content and the elastic modulus on bubble expansion and collapse are also performed.Firstly, based on the cavitation bubble dynamic theory, the relationships between each characteristic parameter are deduced and then an amended cavitation bubble dynamic model is provided. Employing the finite difference calculus, the behavior of the cavitation bubbles in liquids of different viscosity, surface tension, temperature, gas content and condensability are obtained. Meanwhile, the effects of liquid parameters on bubble radius, the velocity and the acceleration of the bubble wall, and the collapse time of the bubble are also analyzed. The numerical results show that liquid parameters have important effects on the expansion and collapse process of single bubble.Secondly, by the optical detection technique based on fiber-coupling beam deflection principle, the laser-induced plasma shock wave, laser-generated bubble and bubble-collapse-induced plasma shock wave are inveatigated by experiment during the high-power laser interacts with an underwater target. Then the dynamic behavior of a bubble in different liquids is systematically investigated. Quantitative relationships between liquid parameters, such as liquid viscosity, surface tension, temperature, and bubble characteristic parameters are also obatained. Good agreement has been established between numerical and experimental results. Moreover, from the modified Rayleigh theory, the liquid-jet velocity and corresponding liquid-jet impact pressure in different liquids can also be deduced. It is shown that the viscous force decreases bubble growth and collapse process, make it expand or collapse less violently. For a high viscosity, few liquid jets can impact the boundary and result in lower cavitation erosion. On the other hand, the surface-tension forces stave bubble growth progress and speed up bubble collapse process, so higher surface-tension increases liquid-jet impact force and produced higher erosive power. In addition, as the temperature of a liquid is one of the basic factors determining liquid viscosity, surface tension and the vapor pressure inside the bubble, it is an important factor determining cavitation and cavitation erosion.Based on the systematical investigation of cavitation bubble oscillation near different boundaries, the influence of the elastic modulus on the behavior of bubbles is obtained. Increasing elastic modulus leads to a significant decrease of bubble radius, collapse time and the bubble energy.These results are valuable in the fields of cavitation erosion, collateral damage in laser surgery, and cavitation-mediated enhancement of pulsed laser ablation of tissue; what is better, these results provide the theoretical and experimental reference to rational use of laser-induced plasma shock wave and cavitation, laser processing, laser lithotripsy, laser ophthalmology, and corresponding hydromechanics, etc.