Asymmetrical breakup of bubbles at a microfluidic T-junction divergence: feedback effect of bubble collision

Abstract

International audienceThis paper aims at studying the asymmetrical breakup of bubbles at a microfluidic T-junction divergence stemming from the feedback effect of bubble behaviors at the T-junction convergence in a loop with the symmetrical branches by a high-speed digital camera. The experiments were performed under gas/liquid flow rates ratio ranging from 0.084 to 4.333. The microfluidic channels have uniform square cross-section with 400 mu m wide and 400 mu m deep. Four bubble behaviors (bubble pair asymmetrical collision, bubble pair staggered flow, single bubble flow and dynamic transformation flow) were observed at the T-junction convergence in different gas and liquid flow rates. The feedback effects of asymmetrical collision and staggered flow of bubble pairs at the T-junction convergence on bubble behavior at the T-junction divergence were mainly investigated. The result showed that the feedback effect is negligible at relatively low flow rates when no collision of bubble pairs occurs. And the bubble pair asymmetrical collision at T-junction convergence or an amplified effect of structured blemish of microchannel at relatively high flow rates is primarily responsible for the asymmetric breakup of bubbles at the T-junction divergence

Shear-induced tail breakup of droplets (bubbles) flowing in a straight microfluidic channel

“…Previous studies have shown that a low viscosity ratio between disperse phase and continuous phase and the presence of surfactants are the prerequisites for forming the tip stream (De Bruijn, 1993;Eggleton et al, 2001;Moyle et al, 2012;Stone, 1994). Our previous studies (Wu et al, 2012) and this work have also proved the conclusion. In addition, the experimental results in this work indicate that the tip stream formation is a time-dependent process.…”

Dynamic Characterization of a Valveless Micropump Considering Entrapped Gas Bubbles

“…Wetting behavior was shown to play a significant role on the formation and motion of the bubbles. Feedback effects of bubble collision on bubble behavior at the convergence and divergence of a T-junction were investigated by Wu et al [23]. Fu et al found that the slug bubble formation process could be divided into expansion, collapsing, and pinch-off.…”

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

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