Drop impact onto a liquid layer of finite thickness: Dynamics of the cavity evolution
Drop impact onto a liquid layer of finite thickness: Dynamics of the cavity evolution
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DOI：
10.1103/physreve.79.036306
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发表时间：
2009-03-01
影响因子：
2.4
通讯作者：
Tropea, Cameron
中科院分区：
文献类型：
--
作者：
Berberovic, Edin;van Hinsberg, Nils P.;Tropea, Cameron
在目前的工作中，提出了对有限厚度的液膜的法向跌落冲击的实验、数值和理论研究。确定并分析了液滴冲击液体表面的动力学、空腔的形状、凹坑中毛细波的形成和传播以及刚性壁上的残余膜厚度。使用高速视频系统观察薄膜内凹坑的形状以及撞击时形成的上升液体层。研究了各种影响参数（例如液滴冲击速度、液膜厚度和液体物理性质（包括粘度和表面张力））对弹坑形成的时间演化的影响。作为实验的补充，使用先进的自由表面捕获模型对现象进行直接数值模拟，该模型基于有限体积数值方法框架中经典流体体积 (VOF) 模型的双流体公式。在该模型中，相分数的传输方程中引入了额外的对流项，这对提高界面分辨率起到了决定性的作用。此外，还开发了一个考虑了液体惯性、粘度、重力和表面张力的凹坑穿透深度的分析模型。如果冲击速度较高，该模型与远离墙壁的早期穿透实验非常吻合。最后，对壁上的残余膜厚度进行了缩放分析，证明与数值预测非常吻合。
In the present work experimental, numerical, and theoretical investigations of a normal drop impact onto a liquid film of finite thickness are presented. The dynamics of drop impact on liquid surfaces, the shape of the cavity, the formation and propagation of a capillary wave in the crater, and the residual film thickness on the rigid wall are determined and analyzed. The shape of the crater within the film and the uprising liquid sheet formed upon the impact are observed using a high-speed video system. The effects of various influencing parameters such as drop impact velocity, liquid film thickness and physical properties of the liquids, including viscosity and surface tension, on the time evolution of the crater formation are investigated. Complementary to experiments the direct numerical simulations of the phenomena are performed using an advanced free-surface capturing model based on a two-fluid formulation of the classical volume-of-fluid (VOF) model in the framework of the finite volume numerical method. In this model an additional convective term is introduced into the transport equation for phase fraction, contributing decisively to a sharper interface resolution. Furthermore, an analytical model for the penetration depth of the crater is developed accounting for the liquid inertia, viscosity, gravity, and surface tension. The model agrees well with the experiments at the early times of penetration far from the wall if the impact velocity is high. Finally, a scaling analysis of the residual film thickness on the wall is conducted demonstrating a good agreement with the numerical predictions.