Interfacial hydrodynamics of electrosprays using leaky dielectric fluids

Electrohydrodynamics (EHD) deals with the motion of a liquid under the influence of an external electric field and a leaky dielectric fluid has low but non-zero conductivity. Many earlier studies on electrohydrodynamics have considered the flow of perfectly dielectric fluids. The present study has established a computational framework to investigate the droplet evolution pattern of leaky dielectric fluids under an externally applied electric field. The Navier-Stokes equations and charge conservation equations are solved using the Coupled Level Set and Volume of Fluid (CLSVOF) method. It was observed that the dynamics of the leaky dielectric liquid emanating from the orifice of an ejector depends on several factors like flow rate, electric field intensity, surface tension, Coulombic forces, electrophoretic forces, etc. Different jetting regimes like choked jets, pulsating jets, steady cone jets, multi jets, etc., were observed based on these conditions. Variations in the drop diameters and jet break-up length at different flow rates were studied, and the results were compared with the available experimental results. It was also observed that the break-up time and detached drop volume can be suitably tuned by varying the strength of the applied electric field.