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首页> 外文期刊>International Journal of Heat and Mass Transfer >Topological structure evolvement of flow and temperature fields in deformable drop Marangoni migration in microgravity
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Topological structure evolvement of flow and temperature fields in deformable drop Marangoni migration in microgravity

机译：微重力下可变形液滴Marangoni迁移中流场和温度场的拓扑结构演化

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摘要

Using the level-set method and the continuum interface model, the axisymmetric thermocapillary migration of a deformable liquid drop immerged in an immiscible bulk liquid with a temperature gradient is simulated numerically with constant material properties of the two phases. Steady terminal state of the motion can always be reached. The dimensionless terminal migration velocity decreases monotonously with the increase of the Marangoni number. Good agreements with space experimental data and most of previous numerical studies in the literature are evident. The terminal topological structure of flow field, in which a recirculation identical to Hill's vortex exists inside the drop, does not change with the Marangoni number. Only slight movement of the location of vortex center can be observed. On the contrary, bifurcations of the terminal topological structure of temperature field occur twice with increasing Marangoni number. At first, the uniform and straight layer-type structure of temperature field at infinitesimal Reynolds and Marangoni numbers wraps inside of the drop due to convective transport of heat as the Marangoni number increases, resulting in the emergence of an onion-type local cooler zone around the center of the drop beyond a lower critical Marangoni number. Expanding of this zone, particularly in the transverse direction, with the increasing of the Marangoni number leads to a cap- or even shell-type structure. The coldest point within the liquid drop locates on the axis. There is a middle critical Marangoni number, beyond which the coldest point will jump from the rear stagnation into the drop, though the topological structure of the temperature field does not change. The second bifurcation occurs at an upper critical Marangoni number, where the shell-type cooler zone inside drops ruptures from the central point and then a torus-type one emerges. The coldest point departs from the axis, and the so-called "cold-eye" appears in the meridian. It is also found that the inner and outer thermal boundary layers along the interface may exist both inside and outside the drop if Ma > 70. But the thickness decreases with the increasing Marangoni number more slowly than the prediction of potential flow at large Marangoni and Reynolds numbers. A velocity shear layer outside the drop is also introduced formally, of which modality may be affected by the convective transports of heat and/or momentum.
机译：使用水平集方法和连续体界面模型，以具有恒定的两相材料特性的数值模拟了浸没在具有温度梯度的不混溶大块液体中的可变形液滴的轴对称热毛细管迁移。始终可以达到运动的稳定终端状态。随着Marangoni数的增加，无因次末端迁移速度单调降低。与空间实验数据和文献中的大多数先前数值研究的良好一致性是显而易见的。流场的终端拓扑结构（其中液滴内部存在与Hill涡旋相同的再循环）不会随Marangoni数变化。只能观察到涡旋中心位置的轻微移动。相反，随着Marangoni数的增加，温度场末端拓扑结构的分支发生两次。首先，由于随着马兰戈尼数的增加，热量的对流传热，无穷小雷诺数和马兰戈尼数的温度场的均匀且平直的层状结构包裹在液滴内部，从而导致在马兰戈尼数附近出现洋葱型局部冷却器区域。下降中心超出了较低的临界Marangoni数。随着Marangoni数的增加，该区域的扩展，特别是在横向方向上的扩展，导致了帽型或什至壳型结构。液滴内最冷的点位于轴上。有一个中间临界Marangoni数，尽管温度场的拓扑结构没有改变，但最冷的点将从后停滞跃升到下降。第二个分叉发生在较高的临界Marangoni数处，其中液滴内部的壳型冷却器区域从中心点破裂，然后出现圆环型。最冷的点偏离轴，所谓的“冷眼”出现在子午线上。还发现，如果Ma> 70，则沿界面的内部和外部热边界层可能在液滴的内部和外部都存在。但是，随着Marangoni数的增加，厚度的减小比对大Marangoni和Reynolds的势流的预测要慢得多。数字。液滴外部的速度剪切层也被正式引入，其形式可能会受到热和/或动量的对流传输的影响。

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  • 来源
    《International Journal of Heat and Mass Transfer》 |2011年第22期|p.4655-4663|共9页
  • 作者

    Jian-Fu Zhao; Liang Zhang; Zhen-Dong Li; Wen-Tao Qin;

  • 作者单位

    Key Laboratory of Microgravity (National Microgravity Laboratory)/CAS, Institute of Mechanics, Chinese Academy of Sciences (CAS), Beijing 100190, China;

    Key Laboratory of Microgravity (National Microgravity Laboratory)/CAS, Institute of Mechanics, Chinese Academy of Sciences (CAS), Beijing 100190, China;

    State Nuclear Power Technology Research & Development Center, Beijing 100190, China;

    Henan Puvang Electric Power Company, Puyang 457000, China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    thermocapillary migration topological structure liquid drop;

    机译：热毛细管迁移拓扑结构液滴;

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