Experimental investigation of self-induced thermocapillary convection for an evaporating meniscus in capillary tubes using micro-particle image velocimetry
Experimental investigation of self-induced thermocapillary convection for an evaporating meniscus in capillary tubes using micro-particle image velocimetry
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DOI：
10.1063/1.1901688
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发表时间：
2005-05-01
影响因子：
4.6
通讯作者：
Christy, JRE
中科院分区：
文献类型：
--
作者：
Buffone, C;Sefiane, K;Christy, JRE
本文报道了小毛细管内蒸发弯月面液体自诱导对流的实验研究。在三重接触线处的强蒸发冷却导致沿液-气界面的温度沿着变化，这产生表面张力梯度，其进而驱动观察到的对流。乙醇和甲醇在三个管尺寸（600，900，和1630 μ m）进行了研究。在液相中的流动模式的特点是使用微粒子图像测速（PIV）技术与矢量空间分辨率为640 nm。热毛细Marangoni对流是观察到在水平方向的毛细管的水平直径部分作为两个contrarotating涡类似的强度，而在垂直直径部分的一个单一的顺时针方向的涡主要存在。这种流型的扭曲可归因于重力。在垂直截面的对称性的失真和损失被发现表现出振荡的行为。对流（由涡量表示）被认为是更强的挥发性液体和较小的管尺寸。与对流时间尺度归一化的涡被发现是较高的挥发性较低的液体，并增加与管半径。因此，使用无量纲液体饱和蒸气压的归一化涡量的进一步校正导致发现独立于管尺寸和液体性质的参数，这表明这里描述的现象是普遍的，并且由三线附近的局部条件决定。(c)2005年美国物理学会。
The present paper reports an experimental investigation of the self-induced liquid convection for an evaporating meniscus in small capillary tubes. The strong evaporative cooling at the triple contact line leads to a variation in temperature along the liquid-vapor interface, which generates a gradient of surface tension that in turn drives the observed convection. Ethanol and methanol in three tube sizes (600, 900, and 1630 mu m) were investigated in this study. The flow pattern in the liquid phase has been characterized using a micro-particle image velocimetry (PIV) technique with a vector spatial resolution of 640 nm. Thermocapillary Marangoni convection is observed in horizontal diametrical sections of the horizontally oriented capillary tubes as two contrarotating vortices of similar strength, whereas in vertical diametrical sections a single clockwise vortex is mostly present. This distortion of the flow pattern could be attributed to gravity. The distortion and loss of symmetry in the vertical section is found to exhibit an oscillatory behavior. The convection (represented by the vorticity) is found to be stronger for more volatile liquids and smaller tube sizes. The vorticity normalized with the convective time scale is found to be higher for the less volatile liquid and to increase with the tube radius. Therefore, a further correction of the normalized vorticity using a dimensionless liquid saturated vapor pressure leads to a parameter that is found independent of the tube size and the liquid properties, suggesting that the phenomena described here are universal and dictated by the local conditions near the triple line. (c) 2005 American Institute of Physics.