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Numerical analysis of deformation and breakup of a compound droplet in microchannels
European Journal of Mechanics - B/Fluids ( IF 2.6 ) Pub Date : 2021-04-06 , DOI: 10.1016/j.euromechflu.2021.03.005
Cuong T. Nguyen , Hung V. Vu , Truong V. Vu , Thuan V. Truong , Nang X. Ho , Binh D. Pham , Hoe D. Nguyen , Vinh T. Nguyen

Compound droplets with different sizes are increasingly used in industrial production and academic research. This study aims to improve understanding of the dynamical behaviors of the compound droplet moving in microchannels. The compound droplet consisting of one inner core is initially concentric and placed at the entrance of a circular channel with a cone at the downstream region. Following this primary channel is a secondary channel that is circular and straight. Manipulation of the droplet is assisted by a flow introduced via the gap between two channels. The numerical results show that when passing through these confined channels, the droplet experiences a finite deformation or breakup mode. In each mode, the deformation or breakup of the compound droplet is also different when changing the values of the parameters including the capillary number, the ratio of the droplet radii, the ratio of the interfacial tension, the size of the secondary channel, the gap size and the cone angle. The finitely deformed droplet can be either nearly ellipsoidal with a deformation index D of around unity (i.e., first deformation mode) or highly elongated with a high D (i.e., second deformation mode). Breakup of the compound droplet happens to the outer droplet, and the breakup point is located either in front of the inner droplet (i.e., first breakup mode) or behind it (i.e., second breakup mode). The simple droplets yielded in the first breakup mode has a higher total volume than those in the second breakup mode. It is found that the droplet experiences the first deformation mode to the first breakup mode, then the second deformation mode and finally the second breakup mode when Ca increases. The regime diagrams of these modes, based on these parameters, are also presented.



中文翻译:

复合液滴在微通道中变形和破裂的数值分析

具有不同尺寸的复合液滴越来越多地用于工业生产和学术研究中。这项研究旨在增进对复合液滴在微通道中移动的动力学行为的理解。由一个内芯组成的复合液滴最初是同心的,并放置在圆形通道的入口处,在下游区域有一个圆锥体。在该主要通道之后是圆形且笔直的次要通道。经由两个通道之间的间隙引入的流动有助于液滴的操纵。数值结果表明,当通过这些受限通道时,液滴会经历有限的变形或破裂模式。在每种模式下 当改变包括毛细管数,液滴半径比,界面张力比,第二通道尺寸,间隙尺寸和锥度在内的参数值时,复合液滴的变形或破裂也不同。角度。有限变形的液滴可以是具有变形指数的近似椭圆形D大约为1(即第一变形模式)或高度拉长而具有高D(即第二变形模式)。复合液滴的破裂发生在外部液滴上,并且破裂点位于内部液滴的前面(即第一分裂模式)或位于内部液滴的后面(即第二分裂模式)。在第一破碎模式下产​​生的简单液滴具有比第二破碎模式下更高的总体积。发现当Ca增加时,液滴经历从第一变形模式到第一破裂模式,然后经历第二变形模式并且最后经历第二破裂模式。还提供了基于这些参数的这些模式的状态图。

更新日期:2021-04-11
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