Engulfment of a drop on solids coated by thin and thick fluid films
Engulfment of a drop on solids coated by thin and thick fluid films
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DOI：
10.1017/jfm.2023.110
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发表时间：
2022-08
影响因子：
3.7
通讯作者：
Chunheng Zhao;V. Kern;A. Carlson;Taehun Lee
中科院分区：
文献类型：
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作者：
Chunheng Zhao;V. Kern;A. Carlson;Taehun Lee
摘要当水滴与不混溶油膜接触时，表现出复杂的界面动力学。当扩散因子为正时，在接触时，油扩散到液滴的液体-空气界面上，首先形成液体桥，其曲率驱动明显的液滴扩散运动，然后吞没液滴。我们研究这种流动使用三相格子玻尔兹曼模拟的基础上的保守相场模型，和实验。惯性和粘性有限的动力学探索使用Ohnesorge数$Oh$和膜高度$H$和初始滴半径$R$之间的比率。这两个制度表明，径向增长的液桥$r$是相当不敏感的膜高度$H$，并与时间$T$为$r\sim T^{1/2}$为$Oh\ll 1$，$r\sim T^{2/5}$为$Oh\gg 1$。对于$Oh\gg 1$，我们的实验表明，这种不混溶的液体桥的增长是类似的混溶滴膜聚结的情况。相反的增长的液体桥，但是，我们发现，后期的吞没动力学和最终的接口配置文件的比例$H/R$的显着影响。
Abstract When an aqueous drop contacts an immiscible oil film, it displays complex interfacial dynamics. When the spreading factor is positive, upon contact, the oil spreads onto the drop's liquid–air interface, first forming a liquid bridge whose curvature drives an apparent drop spreading motion and later engulfs the drop. We study this flow using both three-phase lattice Boltzmann simulations based on the conservative phase field model, and experiments. Inertially and viscously limited dynamics are explored using the Ohnesorge number $Oh$ and the ratio between the film height $H$ and the initial drop radius $R$. Both regimes show that the radial growth of the liquid bridge $r$ is fairly insensitive to the film height $H$, and scales with time $T$ as $r\sim T^{1/2}$ for $Oh\ll 1$, and as $r\sim T^{2/5}$ for $Oh\gg 1$. For $Oh\gg 1$, we show experimentally that this immiscible liquid bridge growth is analogous with the miscible drop–film coalescence case. Contrary to the growth of the liquid bridge, however, we find that the late-time engulfment dynamics and final interface profiles are significantly affected by the ratio $H/R$.