On the contact-line pinning in cavity formation during solid-liquid impact
On the contact-line pinning in cavity formation during solid-liquid impact
复制标题
固液碰撞过程中空腔形成的接触线钉扎
DOI：
10.1017/jfm.2015.574
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发表时间：
2015-11-01
影响因子：
3.7
通讯作者：
Lu, X. -Y.
中科院分区：
文献类型：
--
作者：
Ding, H.;Chen, B. -Q.;Lu, X. -Y.
我们通过实验、模拟和理论分析相结合的方式研究球体和圆柱体撞击液池期间的空腔形成，特别关注接触线钉扎及其与随后空腔演化的关系。这些流动由纳维-斯托克斯扩散界面求解器模拟，该求解器允许移动接触线。在对实验测量量（例如固定接触线的位置和界面形状）达成一致的基础上，我们研究了实验无法获得的流动细节，识别空腔形成中的界面区域并检查撞击物体的几何效应。通过分析钉扎弯月面的力平衡，我们将润湿性、惯性、冲击物体的几何形状、界面弯曲和接触线位置与接触线钉扎联系起来，结果与模拟和实验的结果相比较。除了调节界面弯曲之外，物体的几何形状对液体中低压的大小和流动分离的发生也有显着的影响。因此，具有尖锐边缘的物体比光滑的物体更容易产生空腔。开发了基于 Rayleigh-Besant 方程的理论模型，以定量描述接触线钉扎后空腔的径向膨胀。解决方案的精度很大程度上受到与固定弯月面连接的界面上的几何信息的影响，这表明全局空腔动力学对固定接触线周围局部流动的依赖性。发现空腔壁上的垂直波纹传播遵循空心射流上扰动演化的色散关系。
We investigate the cavity formation during the impact of spheres and cylinders into a liquid pool by using a combination of experiments, simulations and theoretical analysis, with particular interest in contact-line pinning and its relation with the subsequent cavity evolution. The flows are simulated by a Navier-Stokes diffuse-interface solver that allows for moving contact lines. On the basis of agreement on experimentally measured quantities such as the position of the pinned contact line and the interface shape, we investigate flow details that are not accessible experimentally, identify the interface regions in the cavity formation and examine the geometric effects of impact objects. We connect wettability, inertia, geometry of the impact object, interface bending and contact-line position with the contact-line pinning by analysing the force balance at a pinned meniscus, and the result compares favourably with those from simulations and experiments. In addition to adjusting the interface bending, the object geometry also has a significant effect on the magnitude of low pressure in the liquid and the occurrence of flow separation. As a result, it is easier for an object with sharp edges to generate a cavity than a smooth object. A theoretical model based on the Rayleigh-Besant equation is developed to provide a quantitative description of the radial expansion of the cavity after the pinning of the contact line. The accuracy of the solution is greatly affected by the geometrical information on the interface connected to the pinned meniscus, showing the dependence of the global cavity dynamics on the local flows around the pinned contact line. Vertical ripple propagation on the cavity wall is found to follow the dispersion relation for the perturbation evolution on a hollow jet.