Division of Mechanical Engineering, Graduate School of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, 278-8510, Chiba, Japan.
Department of Mechanical Engineering (Department of Mechanical and Aerospace Engineering after Apr. 2023), Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, 278-8510, Chiba, Japan.
J Colloid Interface Sci. 2023 Jul;641:187-196. doi: 10.1016/j.jcis.2023.02.151. Epub 2023 Mar 9.
Multicellular convective structures that are induced in a fluid exposed to temperature difference are commonly observed in nature and in daily life. Different types of basic flow patterns are induced in a free liquid film by thermocapillary effect, whereas the formation of such multicellular structures has not been hitherto unravelled.
A thin film of high-Prandtl-number liquid is prepared in a rectangular aperture of the order of 0.1 mm in thickness sustained by its surface tension. A designated temperature difference is imposed between the end surfaces of the aperture to generate a thermocapillary-driven convection in the free liquid film. We monitor the induced thermal flow patterns to evaluate the cell numbers and their wavelength by experimental and numerical approaches.
The multicellular structure is established by the thermocapillary effect in the free liquid films. The cell number increases in a stepwise manner as the liquid-film width increases. When the cell number increases, another pair of the cells always newly emerges. We determine the wavelength in a non-dimensional manner, and present the variation of the wavelength against the aspect ratio corresponding to the liquid-film width. The results are compared to those of convectional Marangoni-Bénard convection.
在受到温度差影响的流体中，会产生多细胞对流结构，这种结构在自然界和日常生活中很常见。在自由液膜中，热毛细效应会引起不同类型的基本流动模式，而这种多细胞结构的形成至今尚未被揭示。
通过表面张力支撑厚度约为 0.1 毫米的矩形孔中的高普朗特数液体薄膜。在孔的两端表面施加指定的温度差，以在自由液膜中产生热毛细驱动对流。我们通过实验和数值方法监测感应的热流动模式，以评估细胞数量及其波长。
在自由液膜中，通过热毛细效应形成了多细胞结构。随着液膜宽度的增加，细胞数量呈阶梯式增加。当细胞数量增加时，另一对细胞总是新出现的。我们以无量纲的方式确定波长，并给出与液膜宽度对应的长宽比的波长变化。结果与传统的马兰戈尼-贝纳德对流进行了比较。
