Effect of Marangoni Flows on the Shape of Thin Sessile Droplets Evaporating into Air
Effect of Marangoni Flows on the Shape of Thin Sessile Droplets Evaporating into Air
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DOI：
10.1021/acs.langmuir.5b02673
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发表时间：
2015-12-15
期刊：
影响因子：
3.9
通讯作者：
Colinet, Pierre
中科院分区：
文献类型：
--
作者：
Tsoumpas, Yannis;Dehaeck, Sam;Colinet, Pierre
用马赫-曾德尔干涉仪研究了完全润湿液体的自由后退蒸发固着液滴，其中所观察到的有限接触角归因于蒸发。实验获得的液滴形状被发现偏离，在某些条件下，从经典的宏观静态配置文件的固着液滴。观察到的偏差（或其缺乏）解释的Marangoni流由于蒸发引起的热梯度沿沿着液体空气界面。当这种马兰戈尼效应很强时，实验曲线在离接触线一定距离处表现出最大斜率。在这种情况下，轴对称流从接触线被引导到顶点（沿着液气界面），因此将更多的液体输送到液滴的中心并使其看起来膨胀。这些研究结果定量证实的润滑模型占的影响的Marangoni效应的液滴形状的预测。
Freely receding evaporating sessile droplets of perfectly wetting liquids, for which the observed finite contact angles are attributed to evaporation, are studied with a Mach Zehnder interferometer. The experimentally obtained droplet shapes are found to depart, under some conditions, from the classical macroscopic static profile of a sessile droplet. The observed deviations (or the absence thereof) are explained in terms of a Marangoni flow due to evaporation-induced thermal gradients along the liquid air interface. When such a Marangoni effect is strong, the experimental profiles exhibit a maximum of the slope at a certain distance from the contact line. In this case, the axisymmetric flow is directed from the contact line to the apex (along the liquid air interface), hence delivering more liquid to the center of the droplet and making it appear inflated. These findings are quantitatively confirmed by predictions of a lubrication model accounting for the impact of the Marangoni effect on the droplet shape.