Ternary modeling of the interaction between immiscible droplets in a confined shear flow

To investigate the interaction between two equal-sized immiscible droplets in a confined shear flow, a two-dimensional finite-element analysis is carried out by employing a ternary diffuse-interface model. Particularly, the present numerical model allows wetting between the immiscible droplets, and three different types of interaction could be identified, namely, (i) reverse motion, (ii) pass-over motion, and (iii) rotary Janus motion after wetting. A reversing flow that is generated near the droplets can entrain them, resulting in a reverse motion. The rotary Janus motion is observed when the droplets are wetted on each other as the fluid film between them is completely drained. More details of the rotary Janus motion are presented in terms of the droplet trajectory and deformation, and the effect of the initial droplet position, capillary number, and confinement is studied.