Effect of ambient fluid flow upon onset of oscillatory thermocapillary convection in half-zone liquid bridge
Effect of ambient fluid flow upon onset of oscillatory thermocapillary convection in half-zone liquid bridge
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DOI：
10.1007/bf02945971
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发表时间：
2005-03
期刊：
影响因子：
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通讯作者：
Motoki Irikura;Y. Arakawa;I. Ueno;H. Kawamura
中科院分区：
文献类型：
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作者：
Motoki Irikura;Y. Arakawa;I. Ueno;H. Kawamura
在半区液桥中振荡热毛细对流的发生对液桥自由表面的换热和周围空气的运动非常敏感。然而，通过自由表面的热传递对转变机制和振荡流的三维性质的影响尚未完全了解。本文采用实验和数值方法研究了环境气体的热流体行为及其对临界温度的影响。在实验中，通过在两种流体中悬浮示踪颗粒来可视化液体桥和周围空气中的流动。通过放置两个垂直于液桥的分区盘来调节周围空气区的体积。振荡的开始取决于分区磁盘之间的距离；临界马兰戈尼数随距离的减小而增大。为了确定振荡的起始点，用有限差分法对液桥和周围空气进行了三维模拟。计算结果表明，自由表面的换热对振荡的发生有重要影响。计算结果与实验临界值吻合较好。
Onset of the oscillatory thermocapillary convection in a half-zone liquid bridge is known to be sensitive to heat transfer at free surface of the liquid bridge and the ambient air motion. The effect of the heat transfer through the free surface upon the onset of the transition mechanism and three-dimensional nature of the oscillatory flow, however, is not yet fully understood. In the present study, the thermal fluid behavior of the ambient gas and its effect upon the criticality were investigated experimentally and numerically. In the experiment, flows in the liquid bridge and the ambient air were visualized by suspending tracer particles in both fluids. Volume of the ambient air region was adjusted by placing two partition disks perpendicular to the liquid bridge. The onset of oscillation depended on the distance between the partition disks; the critical Marangoni number increased with the decreasing distance. Three-dimensional simulation of the liquid bridge and the ambient air has been performed by the finite difference method in order to determine the onset of the oscillation. The present calculations demonstrate significant influence of the heat transfer at the free surface on the onset of oscillation. The results of calculations yield a good agreement with the experimental critical values.