Influence of electric field on the dynamics of drop formation from submerged orifices

We investigate the influence of an external electric field on the dynamics of drop formation from a submerged orifice in a liquid-liquid system by performing direct numerical simulations. A Volume-of-Fluid solver coupled with the electric field equations is used for simulating the electro-hydrodynamic system. The simulations reveal that the ratio of fluid permittivity and conductivity plays a pivotal role in deciding the volume of the detached drops as well as the limiting length at breakup. For a system wherein the injected fluid has a lower permittivity and higher conductivity than the surrounding fluid (system A), the volume of the drops formed decreases with electric field strength and the breakup length increases. In contrast, when the injected fluid has higher permittivity and lower conductivity than the surrounding fluid, the volume of the detached drops decreases with increasing field strength. The aspect ratio of the detached drops also depends on the relative magnitude of the fluid permittivity and conductivity. The contradictory nature of charge accumulation at the interfaces and the relative difference of electric field strength inside and outside the drop are found to be the root cause for this contrasting behavior between the two systems considered in our study.