Breakup of microdroplets in asymmetricTjunctions

Abstract

Symmetric T junctions have been used widely in microfluidics to generate equal-sized microdroplets, which are applicable in drug delivery systems. A newly proposed method for generating unequal-sized microdroplets at a T junction is investigated theoretically and experimentally. Asymmetric T junctions with branches of identical lengths and different cross sections are utilized for this aim. An equation for the critical breakup of droplets at asymmetric T junctions and one for determining the breakup point of droplets are developed. A good agreement was observed between the theories (present and previous) and the experiments.

Asymmetric breakup of a droplet in an axisymmetric extensional flow

“…(17)] could be employed to describe the breakup with negligible errors when the asymmetry is small. Figure 9.…”

“…In 2004, Link and co-workers [9] successfully broke the droplet into two daughter droplets with unequal sizes through T-junctions with two side arms of unequal lengths, which verified very well that the asymmetric geometry of microchannels could generate an asymmetric flow field and result in the asymmetric deformation and breakup of droplets. After that, various devices have been designed to study the asymmetric rheology behaviors of droplets in confined geometries, such as bifurcating channel [16], asymmetric T junction [17], Y junctions [16], obstacles [18,19] etc. In 2013, Salkin and co-workers [20] investigated the fragmentation of isolated slugs against rectangular obstacles and asymmetric loops.…”

Split of two-phase plug flow with elongated bubbles at a microscale branching T-junction

“…1. Thus, the behavior of the plug flows at the branching T-junctions (Ménétrier-Deremble and Tabeling, 2006;Azzi et al, 2010;Hong et al, 2010;He et al, 2011;Wolden, 2012;Chen et al, 2012Chen et al, , 2013Wang et al, 2014) or at the impacting T-junctions (Link et al, 2004;Jullien et al, 2009;Leshansky and Pismen, 2009;Fu et al, 2011;Afkhami et al, 2011;Hoang et al, 2013;Bedram and Moosavi, 2013;Samie et al, 2013) could be well predicted by analyzing the dynamics of the unit cell, provided that the distance between the bubbles (or the length of the liquid slugs) is long enough to avoid mutual interaction between them. Here, the branching T-junction implies a straight channel with a perpendicular side arm, whereas the impacting T-junction has two downstream channels both perpendicular to the upstream channel but pointing out in opposite directions from each other (Chen et al, 2014).…”

Three dimensional simulations of droplet formation in symmetric and asymmetric T-junctions using the color-gradient lattice Boltzmann model

“…For example, Shi et al [20] simulated the droplet formation in a two-dimensional symmetric T-junction by using the free-energy lattice Boltzmann method developed by Liu and Zhang [9], and investigated the effect of various parameters on the droplet size, including flow rate ratio, capillary number, geometry, and wetting property. Quite recently, asymmetric T-junctions have emerged as a promising tool for microfluidic functions, e.g., the asymmetric T-junctions have been applied in droplet breakup process to divide one droplet into two unequal parts [21][22][23]. In asymmetric T-junctions, the width of inlet channel of the continuous phase w c1 is unequal to the width of outlet channel w c2 , which provides a new controlling parameter for droplet formation, written as the channel width ratio Z ¼ w c1 =w c2 .…”