液滴在液面上的相互作用对很多自然过程和工业应用都非常重要。在很多情况下,其系统是多组分的,这导致液面产生马兰戈尼流动,有可能使液滴之间出现斥力。本研究通过观察两个漂浮在乙醇-水混合液表面且完全相同的油滴的运动,研究“麦圈效应”产生的吸引力与溶质马兰戈尼流产生的斥力的综合影响。实验中发现了三种典型行为：排斥、吸引-合并和吸引-反弹;即液滴相互排斥,相互吸引后合并,相互吸引后接触并反弹。通过对引力与斥力的分析得到了用于区分液滴排斥和吸引行为的标度律。对于相互吸引的液滴,液滴由合并到反弹的转变则是由于润滑效应：当液滴浸没在液池中的部分大于半个球体时,两液滴之间会在接触时形成一个润滑液层,这阻止了液滴的合并。该研究有助于加深对液面上液滴操控的理解。
The interaction of drops floating on liquid surfaces is important for many natural processes and industrial applications. In many cases, the system is multicomponent, leading to Marangoni flows on the surface, which might lead to repulsive forces between the drops. Here we investigate the combined effect of the attractive ``Cheerios effect'' and the repulsive solutal Marangoni flow by observing the behaviors of two identical oil drops floating on a partially miscible pool made of ethanol-water mixtures. Three typical behaviors are found: Repel, Attract-Coalesce and Attract-Rebound, in which the drops repel each other, attract each other and then coalesce, and attract and rebound upon contact. A scaling theory based on the two competing forces is developed to distinguish the repulsive and attractive behaviors of the drops. For the transition from Attract-Coalesce to Attract-Rebound, a lubrication layer is found to form when the immersed lower halves of the drops are more than half a sphere, which prevents the drops from coalescing. Our work may improve the knowledge on drop manipulations on liquid surfaces.
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