Droplet generation at Hele-Shaw microfluidic T-junction
Droplet generation at Hele-Shaw microfluidic T-junction
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DOI：
10.1063/1.5086808
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发表时间：
2019-02-01
影响因子：
4.6
通讯作者：
Leshansky, A. M.
中科院分区：
文献类型：
--
作者：
Chakraborty, I.;Ricouvier, J.;Leshansky, A. M.
本文提出了一种数值模拟与实验相结合的方法，研究了在垂直方向上流动受到强烈限制的浅T型微流控通道中液滴生成的动力学过程。数值模拟采用准二维Hele-Shaw近似，界面捕捉过程基于耦合Level-Set和Volume-of-Fluid方法。我们调查的毛细管数，Ca，通道的几何形状（横截面的纵横比，chi），和流量（分散连续相）的比率，伽玛，对液滴破碎的动力学的影响。根据钙，三个不同的流动制度被确定：挤压，撕裂和喷射。在低钙的压缩制度中，所产生的液滴的大小取决于chi和Gamma，而它几乎是不敏感的钙在协议以前的研究。在中等Ca的撕裂状态下，液滴尺寸减小为类似于Ca-1/3，而它只是chi和Gamma的弱函数。最后，在喷射状态下，在足够高的Ca下发生两相的稳定并流。基于Hele-Shaw流动近似的数值预测与我们的内部实验结果非常一致，表明所提出的方法可以有效地用于计算成本低且足够准确的浅微流体装置中两相流的建模。由AIP Publishing授权出版。
We proposed the combined numerical and experimental study of the dynamics of droplets generation at shallow microfluidic T-junction, where the flow is strongly confined in the vertical direction. The numerical simulation is performed by employing quasi-2D Hele-Shaw approximation with an interface capturing procedure based on coupled Level-Set and Volume-of-Fluid methods. We investigate the effect of the capillary number, Ca, the channel geometry (cross section aspect ratio, chi), and the flow rate (disperse-to-continuous phases) ratio, Gamma, on the dynamics of the droplet breakup. Depending on Ca, three distinct flow regimes are identified: squeezing, tearing and jetting. In the squeezing regime at low Ca, the size of the generated droplets depends on chi and Gamma, while it is almost insensitive to Ca in agreement to previous studies. In the tearing regime at moderate Ca, the droplet size decreases as similar to Ca-1/3, while it is only a weak function of chi and Gamma. Finally, in the jetting regime, the steady co-flow of both phases takes place at high enough Ca. The numerical predictions based on the Hele-Shaw flow approximation are in excellent agreement with our in-house experimental results, demonstrating that the proposed approach can be effectively used for computationally inexpensive and adequately accurate modeling of biphasic flows in shallow microfluidic devices. Published under license by AIP Publishing.