Simulations of microfluidic droplet formation using the two-phase level set method
Simulations of microfluidic droplet formation using the two-phase level set method
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DOI：
10.1016/j.ces.2011.06.034
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发表时间：
2011-10-15
影响因子：
4.7
通讯作者：
Zimmerman, William B.
中科院分区：
文献类型：
--
作者：
Bashir, Shazia;Rees, Julia M.;Zimmerman, William B.
微滴的形成是一个新兴的研究领域，因为它在基于微流控的芯片实验室设备中有着广泛的应用。我们的目标是了解微流控T形结中液滴形成的动力学，以便优化微流控装置的操作。对这一过程的了解构成了许多潜在应用的基础：新材料的合成、制药、化妆品和食品行业的产品配方。两相水平集方法非常适合于跟踪两种不相容流体之间的界面，已被用来对T形结中液滴的形成进行数值模拟。数值预测与实验观测结果吻合较好。流量比、毛细管数、粘度比和两不相容流体之间的界面张力等参数对液滴产生的物理过程有一定的影响。本文系统地研究了表面润湿性对表面润湿性的影响，通过改变接触角可以控制表面润湿性。由于两相流中液体之间的竞争润湿可能会引起不稳定的流型，因此通常需要尽量减少这种现象，因为它可能会扰乱均匀液滴的正常生产。数值模拟预测，当粘度比lambda(分散相粘度与连续相粘度之商)为O(1)时，润湿性对液滴长度的影响比Lambda为O(0.1)时更加显著。在超疏水区域，对于所有毛细管数，液滴大小与接触角无关。在给定的界面张力值下，当lambda为O(1)时，液滴长度大于lambda为O(0.1)时的液滴长度。液滴长度随界面张力Sigma的增加是In Sigma的函数，回归曲线的系数取决于粘度比。(C)2011爱思唯尔有限公司。保留所有权利。
Microdroplet formation is an emerging area of research due to its wide-ranging applications within microfluidic based lab-on-a-chip devices. Our goal is to understand the dynamics of droplet formation in a microfluidic T-junction in order to optimize the operation of the microfluidic device. Understanding of this process forms the basis of many potential applications: synthesis of new materials, formulation of products in pharmaceutical, cosmetics and food industries. The two-phase level set method, which is ideally suited for tracking the interfaces between two immiscible fluids, has been used to perform numerical simulations of droplet formation in a T-junction. Numerical predictions compare well with experimental observations. The influence of parameters such as flow rate ratio, capillary number, viscosity ratio and the interfacial tension between the two immiscible fluids is known to affect the physical processes of droplet generation. In this study the effects of surface wettability, which can be controlled by altering the contact angle, are investigated systematically. As competitive wetting between liquids in a two-phase flow can give rise to erratic flow patters, it is often desirable to minimize this phenomenon as it can lead to a disruption of the regular production of uniform droplets. The numerical simulations predicted that wettability effects on droplet length are more prominent when the viscosity ratio lambda (the quotient of the viscosity of the dispersed phase with the viscosity of the continuous phase) is O(1), compared to the situation when lambda is O(0.1). The droplet size becomes independent of contact angle in the superhydrophobic regime for all capillary numbers. At a given value of interfacial tension, the droplet length is greater when lambda is O(1) compared to the case when lambda is O(0.1). the increase in droplet length with interfacial tension, sigma, is a function of In sigma with the coefficients of the regression curves depending on the viscosity ratio. (c) 2011 Elsevier Ltd. All rights reserved.