Marangoni instabilities for convective mobile interfaces during drop exchange: Experimental study and CFD simulation
Marangoni instabilities for convective mobile interfaces during drop exchange: Experimental study and CFD simulation
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DOI：
10.1016/j.colsurfa.2012.10.032
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发表时间：
2014-01-20
影响因子：
5.2
通讯作者：
Miller, R.
中科院分区：
文献类型：
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作者：
Javadi, A.;Karbaschi, M.;Miller, R.
利用表面活性染料对液滴内液体的流入模式进行了实验研究，并与CFD模拟结果进行了比较。实验结果与仿真结果吻合。CFD模拟结果与水滴轮廓分析张力测量法（PAT）测量的表面张力值吻合较好。表面活性剂的流入引起了马兰戈尼不稳定性，这是由表面活性剂局部到达液滴表面引起的。与模拟结果相比，实验观察到的这种马兰戈尼不稳定性的开始有大约10秒的延迟。讨论了不同的情况，包括边界层障碍，动力学控制的吸附机制，更新移动界面的方式，以及发生这种不稳定性所需的临界马兰戈尼数。结果表明，除了通常定义的临界马兰戈尼数外，马兰戈尼不稳定性延迟的主要原因可能是液滴表面的迁移率，这可能会阻止这种表面效应出现所需的准静态吸附层的建立。(C) 2012 Elsevier B.V.版权所有
The inflow pattern of liquid into a droplet is studied experimentally using a surface active dye and compared with results of CFD simulations. The results show visual agreement between experiments and simulations. The CFD simulations show also good agreement with the surface tension measured by drop profile analysis tensiometry (PAT). The inflow of the surfactant induces a Marangoni instability caused by the local arrival of the surfactant at the drop surface. The onset of this Marangoni instability observed experimentally has a delay of about 10 s when compared with the simulation results. Different scenarios are discussed, including a boundary layer barrier, a kinetic-controlled adsorption mechanism, the way of renewing a mobile interface, and a critical Marangoni number required for the onset of such instability. It turns out that besides the commonly defined critical Marangoni number, the main reason for delay of Marangoni instability is possibly the mobility of the drop surface which can prevent the establishment of a quasi static adsorbed layer required for the appearance of such surface effect. (C) 2012 Elsevier B.V. All rights reserved.