An integrated hydrodynamic model that involves a laser heat source, surface evaporation, and interfacial driving forces is developed to simulate the complex physical process of a nanosecond pulsed laser impacting on a water droplet. Droplet deformation tracked by the coupled level set and volume of fluid method is contrasted with the experimental results, and it is shown that the coupled model can be used to simulate the droplet expansion dynamics. From the simulation of droplet deformation, it can be found that, with increasing laser energy, the droplet becomes thinner. With the highest laser energy, the jet on the opposite side to laser impact is interpreted as the flow of high-speed fluid near the axis, which is also confirmed by the velocity field. The simulated temperature reaches or even exceeds the critical value, and the recoil pressure does not completely cover the whole hemispherical surface of the droplet. The liquid-removal depth, which represents the distance that the liquid-phase interface retreats during evaporation, is much shallower than the absorption depth. It can be concluded that propulsion is gained from the intense evaporation of the superheated layer.

中文翻译：

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纳秒脉冲激光对水滴影响的数值研究

开发了一个涉及激光热源、表面蒸发和界面驱动力的集成流体动力学模型，以模拟纳秒脉冲激光撞击水滴的复杂物理过程。将耦合水平集和流体体积法跟踪的液滴变形与实验结果进行对比，表明耦合模型可用于模拟液滴膨胀动力学。从液滴变形的模拟可以发现，随着激光能量的增加，液滴变得更薄。在激光能量最高的情况下，激光撞击对面的射流被解释为轴附近的高速流体流动，这也得到了速度场的证实。模拟温度达到甚至超过临界值，并且反冲压力没有完全覆盖液滴的整个半球表面。液体去除深度，代表液相界面在蒸发过程中后退的距离，比吸收深度浅得多。可以得出结论，推进力是从过热层的强烈蒸发中获得的。