A three-dimensional level set method for droplet sorting using a non-uniform electric field

Abstract

In this research, we have developed a computational method for droplet sorting using a non-uniform electric field. The method is based on a three-dimensional level-set method and the leaky-dielectric electrohydrodynamics (EHD) model. Level-set method is used for modeling the interface of the two-phase flow system. The electrostatic phenomenon is dealt with the leaky dielectric-leaky dielectric fluid system. At first, we validated our developed model for a classical flow case: a droplet subjected to a uniform electric field. The results obtained from the present computational method show good agreement with the existing results from the literature. After validation, we implemented the developed code in a practical application of droplet sorting using a non-uniform electric field (known as dielectrophoresis) in a rectangular microchannel with an orthogonal side channel. We mainly focus on the sorting of the droplet without and with the electric field effect as a function of different parameters of the problem. Depending on the intensity of the physical parameters, the droplet can flow into either the downstream main channel or it can sort into the orthogonal side branch. The sorting of a droplet is characterized by the critical branch ratio, qc above which the droplet enters the side branch. The results and conclusions from the present thesis facilitate the understanding of the fundamental principles and mechanisms of electrohydrodynamics (EHD)-based droplet sorting using dielectrophoresis in microfluidic channels. Therefore, present results can have potential usefulness toward the design and development of droplet-based microfluidic devices.