用于模拟凝固金属液滴撞击的改进相场框架
An improved phase-field framework for simulating impacts of solidifying metal drops
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中文总结 AI 辅助
该研究针对传统相场公式无法模拟凝固金属液滴撞击后熔体回缩的问题，改进相场框架并引入壁能与惩罚项，经锡液滴撞击实验验证，可准确捕捉相关动力学并得到稳定溅射物直径。
中文摘要 AI 辅助
本文通过针对性的自由能修改，开发了一种用于模拟凝固熔融金属液滴撞击动力学的改进相场方法。传统的Cahn-Hilliard-Navier-Stokes（CHNS）公式通常无法捕捉液滴凝固部分的熔体回缩，因为在单序参数的扩散界面模型中，新形成的固体区域未被视为实际的内部边界。因此，该公式缺乏能够驱动熔体在凝固溅射物上回缩的内部润湿条件或局部壁能机制。为解决这一局限，研究人员在自由能中添加了一个扩散域壁能项，其化学势贡献在扩散的液体-凝固材料-气三相线区域附近起作用，使剩余熔体能够在凝固溅射物上回缩。此外，研究人员引入了一个凝固惩罚项，以固定撞击过程中形成的凝固溅射物，并抑制冻结区域内残留的Cahn-Hilliard扩散导致的非物理界面运动。该公式通过凝固锡液滴撞击的基准实验进行验证，结果显示，局部壁能项能够捕捉最大铺展后的熔体回缩，而惩罚项可有效阻止凝固溅射物的运动。与实验、体积流体模拟及标准相场预测的定性和定量比较表明，所提公式能够捕捉最大铺展后的熔体回缩，并提供稳定最终溅射物直径的准确估计值。
英文摘要
Here, an improved phase-field method for simulating the impact dynamics of solidifying molten metal droplets is developed using targeted free-energy modifications. Conventional Cahn-Hilliard-Navier-Stokes (CHNS) formulations generally do not capture melt retraction over a solidified portion of the droplet, because the newly formed solid region is not treated as an actual internal boundary in a single-order-parameter diffuse-interface model. As a result, the formulation lacks an internal wetting condition or localized wall-energy mechanism capable of driving melt retraction over a solidified splat. To address this limitation, a diffuse-domain wall-energy term is added to the free energy, with a chemical-potential contribution that is active near the diffuse liquid-solidified-material-gas triple-line region, enabling the remaining melt to retract over a solidified splat. In addition, a solidification penalty term is introduced to immobilize the solidified splat formed during impact and suppress unphysical interface motion caused by residual Cahn-Hilliard diffusion inside the frozen region. The proposed formulation is validated against benchmark experiments on impacts of solidifying tin droplets. The results reveal that the localized wall-energy term captures post-maximum-spread melt retraction, while the penalty term effectively arrests motion of the solidified splat. Qualitative and quantitative comparisons with experiments, volume-of-fluid simulations, and standard phase-field predictions demonstrate that the proposed formulation captures post-maximum-spread melt retraction and provides an accurate estimate of the stabilized final splat diameter.
