The Influence of Vortex Flow in the Dispersed Phase on Droplet Formation Dynamics

Abstract This work explores the characteristics of a two-phase system's dispersed phase flow that interacts inside the microfluidic channel at the junction. Direct visualization and μ-particle image velocimetry measurements are performed on the interaction of two immiscible fluids in different stepped flow-focusing (SFF) channels for droplet formation. The capillary instabilities produce the counter-rotating vortex flow in dispersed phase fluid at the interface, which plays a significant role in droplet formation. The vortex flow has been analyzed using various data processing techniques. The effect of flowrate and step channel dimensions on the evolution of the vortices generated during droplet thread propagation is studied. The strength of the vortex and momentum flux led to the development of more bulging shapes in the droplet thread. Also, this study exhibits transient flow characteristics during the detachment stage and contributes to understanding its influences on mass transfer at the microlevel dimensions.