Induction of Marangoni convection in pure water drops
Induction of Marangoni convection in pure water drops
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DOI：
10.1063/1.4966542
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发表时间：
2016-10
影响因子：
4
通讯作者：
Yutaku Kita;Alexandros Askounis;M. Kohno;Y. Takata;Jungho Kim;K. Sefiane
中科院分区：
文献类型：
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作者：
Yutaku Kita;Alexandros Askounis;M. Kohno;Y. Takata;Jungho Kim;K. Sefiane
我们报告通过红外热成像对纯水滴中的热毛细管或马兰戈尼流动进行实验观察/可视化。马兰戈尼流是通过用激光局部加热中心正下方的基板，在液滴上施加温度梯度来诱导的。显然，沿着液体-空气界面的温度梯度约为。马兰戈尼流需要 2.5 °C 才能作为双涡流启动，随后的梯度约为 2.5 °C。 1.5°C 来维持它们。涡流表现出振荡行为，它们合并和分裂，以使液滴补偿不均匀的加热和冷却。这些模式的起源是通过比较无量纲马兰戈尼数和瑞利数来确定的，这显示了马兰戈尼对流的主导地位。第二组实验进一步支持了这一事实，其中当液滴倒置（悬滴）时观察到相同的流动模式。
We report on experimental observations/visualization of thermocapillary or Marangoni flows in a pure water drop via infrared thermography. The Marangoni flows were induced by imposing a temperature gradient on the drop by locally heating the substrate directly below the center with a laser. Evidently, a temperature gradient along the liquid-air interface of ca. 2.5 °C was required for the Marangoni flows to be initiated as twin vortices and a subsequent gradient of ca. 1.5 °C to maintain them. The vortices exhibited an oscillatory behavior where they merged and split in order for the drop to compensate for the non-uniform heating and cooling. The origin of these patterns was identified by comparing the dimensionless Marangoni and Rayleigh numbers, which showed the dominance of the Marangoni convection. This fact was further supported by a second set of experiments where the same flow patterns were observed when the drop was inverted (pendant drop).