Elongated Cavitation Bubbles Induced by Long-Pulsed Lasers: A Computational Study

Laser-induced cavitation plays a significant role in many engineering and biomedical applications. If the duration of laser pulse is similar to or longer than the local acoustic time scale (i.e. long-pulsed laser), the dynamics of the cavitation bubble is determined not only by the initial event of bubble nucleation, but also by the continuation of laser absorption and phase transition. In this talk, we present a coupled photo-thermal-mechanical model to predict the formation of non-spherical, elongated bubbles due to long-pulsed laser radiation. Key components of the computational framework will be introduced, including the FInite Volume method with Exact multi-material Riemann problems (FIVER), an embedded boundary method for fluid-laser coupling, and a customized local level set method for interface tracking. The numerical results will be compared with high-speed images obtained from Ho:YAG and thulium fiber laser experiments. A parametric study will be presented to investigate the effects of laser beam properties on bubble shape and the efficiency of energy delivery.