Formation of viscoelastic droplets in asymmetrical parallel microchannels

Abstract

The dynamics of viscoelastic droplet formation in T-shaped asymmetric parallel microchannels are investigated using a high-speed camera. The effects of fluid viscoelasticity and flow rates of the two phases on the stability and uniformity of droplets, fluid flow distribution, and droplet formation period are explored. The results reveal that the viscoelasticity advances the transition from the squeezing stage to the rapid pinch-off stage, slows down the necking of rapid pinch-off stage and increases the duration of the stretching stage. It is found that the stability is significantly improved by increasing the continuous phase flow rate, and the droplet uniformity is affected by both the flow rates of the two phases and the fluid elasticity. In addition, prediction models for the fluid flow distribution, droplet size and droplet formation period are established. At last, the breakup mode of different elasticity filament and the satellite droplet size are studied. It is concluded that the increased elasticity contributes to the elimination of satellite droplets, and the satellite droplet size are affected by the fluid elasticity and the continuous phase flow rate.