Shear-thinning droplet formation inside a microfluidic T-junction under an electric field

Researchers usually simplify their simulations by considering the Newtonian fluid assumption in microfluidic devices. However, it is essential to study the behavior of real non-Newtonian fluids in such systems. Moreover, using the external electric or magnetic fields in these systems can be very beneficial for manipulating the droplet size. This study considers the simulation of the process of non-Newtonian droplets’ formation under the influence of an external electric field. The novelty of this study is the use of a shear-thinning fluid as the droplet phase in this process, which has been less studied despite its numerous applications. The effects of an external electric field on this process are also investigated. Aqueous carboxymethyl cellulose (CMC) solution with different mass concentrations is selected as the non-Newtonian fluid of the droplet phase. The level set numerical method is used to analyze the formation of droplets in a T-junction. First, the effects of changing the key parameters such as the inlet velocities of phases, the concentration of the droplet phase, and the contact angle and the time of first droplet formation are investigated. The results indicate that as the concentration of the droplet phase increases, the diameter of the droplet decreases. Next, by applying a voltage difference to the system, an electric field is created inside the system. It is found that the stronger the electric field, the larger the droplet size due to the direction of electric forces applied to the interface of the droplet.