Dynamics of droplet formation and mechanisms of satellite droplet formation in T-junction microchannel

Abstract

The dynamics of droplet formation in T-junction microchannel was visually investigated. Three different droplet formation flow patterns were observed: single satellite droplet, no satellite droplet, multiple satellite droplets. The formation process of droplets could be divided into four sequential stages: squeezing stage, transition stage, pinch-off stage, and filament thinning stage. In the squeezing stage and pinch-off stage, the minimum neck width of the droplet varies linearly with time, and the neck thinning rate is independent of continuous phase capillary number. In the transition stage, the minimum neck width of the droplet follows power-law relation with time, and the thinning rate of the droplet neck increases with continuous phase capillary number. In the filament rupture stage, the rupture mode of the filament varies with the increase of continuous phase flow rate. The different satellite droplet formation flow patterns and mechanisms were studied and elucidated.