Electrowetting Induced Droplet Generation in T-Junctions

Abstract

In this study, droplet generation in a T-junction fluidic channel device was studied by using electrowetting actuation with the consideration of different droplet forming regimes. For this purpose, the finite element method (FEM) was used to solve the unsteady Naiver–Stokes equation. In addition, the level set method was applied to capture the interface between two phases. It was shown that there was a good agreement between obtained data and other work during the process of droplet generation in the absence of electrowetting actuation which results in the decrease in the size of the droplet with increasing the velocity ratios. In the shearing regime, the effectiveness of electrowetting on the droplet generation frequency as well as droplet size is visible in a T-junction fluidic channel since after applying voltages, specified with nondimensional electrowetting numbers of η=0.5 and 1.2, dispersed phase is pulled out into the oil phase. In fact, by applying the voltage on the top wall, the droplet breakup time was decreased and smaller droplets were produced. Finally, different important parameters such as pressure difference across the interface as well as shear stress exerted from the continuous phase shear stress were examined in detail.