Effect of Marangoni Number on Thermocapillary Convection and Free-Surface Deformation in Liquid Bridges

分类： 动力与电气工程 >> 工程热物理学 提交时间： 2017-06-22 合作期刊: 《热科学学报》

Zhang, Y [ 1 ] Huang, HL [ 1 ] Zhou, XM [ 2 ] Zhu, GP [ 1 ] Zou, Y [ 1 ]

摘要： Floating zone technique is a crucible-free process for growth of high quality single crystals. Unstable thermocapillary convection is a typical phenomenon during the process under microgravity. Therefore, it is very important to investigate the instability of thermocapillary convection in liquid bridges with deformable free-surface under microgravity. In this works, the Volume of Fluid (VOF) method is employed to track the free-surface movement. The results are presented as the behavior of flow structure and temperature distribution of the molten zone. The impact of Marangoni number (Ma) is also investigated on free-surface deformation as well as the instability of thermocapillary convection. The free-surface exhibits a noticeable axisymmetric (but it is non-centrosymmetric) and elliptical shape along the circumferential direction. This specific surface shape presents a typical narrow 'neck-shaped' structure with convex at two ends of the zone and concave at the mid-plane along the axial direction. At both theta = 0 degrees and theta = 90 degrees, the deformation ratio increases rapidly with Ma at first, and then increases slowly. Moreover, the hydrothermal wave number m and the instability of thermocapillary convection increase with Ma.

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