Numerical simulation for a droplet fission process of electrowetting on dielectric device

Electrowetting has been proposed as a technique for manipulating droplets surrounded by air or oil. In this paper, we discuss the modeling and simulation of the droplet fission process between two parallel plates inside an electrowetting on dielectric (EWOD) device. Since the gap between the plates is small, we use the two-phase Hele-Shaw flow as a model. An immersed boundary (IB) method is employed to solve the governing equations and a local level set method is used to track the drop interface. For comparison purposes, the same set of two-phase Hele-Shaw equations are also solved directly using the ghost-fluid (GF) method. Numerical results are consistent with experimental observations reported in the literature, provided that care is taken to treat the contact angle. Key words: electrowetting, ghost fluid method, Hele-Shaw equations, immersed boundary method, local level set method, microfluidics, moving interface, two-phase flow