Transition from squeezing to dripping in a microfluidic T-shaped junction
Transition from squeezing to dripping in a microfluidic T-shaped junction
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DOI：
10.1017/s002211200700910x
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发表时间：
2008-01-25
影响因子：
3.7
通讯作者：
Stone, H. A.
中科院分区：
文献类型：
--
作者：
De Menech, M.;Garstecki, P.;Stone, H. A.
我们描述了一个数值研究的结果，在有限的几何形状的微流控T-路口的不混溶流体的流的动力学的分裂。我们确定了三种不同的制度形成的液滴：挤压，滴和喷射，提供了一个统一的图片典型的微流体系统的乳化过程。破碎的挤压机制是特定于微流体系统，因为流体的物理限制对界面动力学具有显著的影响。在这种制度下，破碎过程主要是由一个新兴的液滴上游的压力的积累和破碎的动力学和液滴的大小的缩放的影响只有很弱的毛细管数的值。滴落制度，而显然同源的无界的情况下，也受到显着的影响，受约束的几何形状，这些影响修改的比例定律的液滴的大小来自界面和粘性应力的平衡。最后，喷射方案仅在非常高的流速下或在低界面张力下（即，毛细管数的较高值）设置，类似于无界情况。
We describe the results of a numerical investigation of the dynamics of breakup of streams of immiscible fluids in the confined geometry of a microfluidic T-junction. We identify three distinct regimes of formation of droplets: squeezing, dripping and jetting, providing a unifying picture of emulsification processes typical for microfluidic systems. The squeezing mechanism of breakup is particular to microfluidic systems, since the physical confinement of the fluids has pronounced effects on the interfacial dynamics. In this regime, the breakup process is driven chiefly by the buildup of pressure upstream of an emerging droplet and both the dynamics of breakup and the scaling of the sizes of droplets are influenced only very weakly by the value of the capillary number. The dripping regime, while apparently homologous to the unbounded case, is also significantly influenced by the constrained geometry; these effects modify the scaling law for the size of the droplets derived from the balance of interfacial and viscous stresses. Finally, the jetting regime sets in only at very high flow rates, or with low interfacial tension, i.e. higher values of the capillary number, similar to the unbounded case.