School of Mathematics, Computer Science & Engineering, Department of Mechanical Engineering & Aeronautics, City University of London, Northampton Square, London, United Kingdom.
PLoS One. 2018 Sep 25;13(9):e0204125. doi: 10.1371/journal.pone.0204125. eCollection 2018.
The impact of a laser pulse onto a liquid metal droplet is numerically investigated by utilising a weakly compressible single phase model; the thermodynamic closure is achieved by the Tait equation of state (EoS) for the liquid metal. The smoothed particle hydrodynamics (SPH) method, which has been employed in the arbitrary Lagrangian Eulerian (ALE) framework, offers numerical efficiency, compared to grid related discretization methods. The latter would require modelling not only of the liquid metal phase, but also of the vacuum, which would necessitate special numerical schemes, suitable for high density ratios. In addition, SPH-ALE allows for the easy deformation handling of the droplet, compared to interface tracking methods where strong mesh deformation and most likely degenerate cells occur. Then, the laser-induced deformation of the droplet is simulated and cavitation formation is predicted. The ablation pattern due to the emitted shock wave and the two low pressure lobes created in the middle of the droplet because of the rarefaction waves are demonstrated. The liquid metal droplet is subject to material rupture, when the shock wave, the rarefaction wave and the free surface interact. Similar patterns regarding the wave dynamics and the hollow structure have been also noticed in prior experimental studies.
利用弱可压缩单相模型对激光脉冲撞击液态金属液滴的过程进行数值研究；利用液态金属的泰特状态方程（EOS）实现热力学封闭。与基于网格的离散化方法相比，光滑粒子流体动力学（SPH）方法在任意拉格朗日-欧拉（ALE）框架中具有更高的数值效率。后者不仅需要对液态金属相进行建模，还需要对真空相进行建模，这将需要特殊的数值方案，以适应高密度比。此外，与界面跟踪方法相比，SPH-ALE 允许更容易地处理液滴的变形，因为界面跟踪方法会发生强烈的网格变形和可能的退化单元。然后，模拟了液滴的激光诱导变形，并预测了空化的形成。展示了由于发射激波和由于稀疏波在液滴中间形成的两个低压叶导致的烧蚀模式。当冲击波、稀疏波和自由表面相互作用时，液态金属液滴会发生材料破裂。在先前的实验研究中也注意到了类似的关于波动力学和空心结构的模式。
