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The application of an electric field on a fluid in motion gives rise to unique features and flow manipulation capabilities. Technologies ranging from bubble formation, droplet generation, fiber spinning, and many others are predicated on this type of flows, often referred to as Electrohydrodynamics (EHD). In this paper, we present a numerical methodology that allows for the modeling of such processes in a generalized way. The method can account for the premixing of various liquid species, the injection of gases in the mixture and the interaction of such complex multiphase flow with an electric field, static or AC. The domain in which these processes take place can be of arbitrary geometric complexity, allowing for design and optimization of complex EHD devices. Our study looks at the critical phases of some of these processes and emphasizes the strong coupling of fluid mechanics and electric fields and the influence of the electric field on fluid flow and vice versa. The conservation of mass and momentum, with appropriate additional force terms coming from the presence of the electric field, and the electrostatic equations are coupled together and solved using the Finite Volume method. The Volume of Fluid (VoF) technique is used to track free surfaces dynamically. The solution procedure iteratively computes electric body and surface forces and then includes those into the Navier-Stokes equation to predict the velocity field and other fluid parameters. No initial shape is assumed for the fluid(s) and charge distributions. The methodology presented handles two-dimensional, axisymmetric. and full three-dimensional cases of arbitrary geometric complexity, allowing for mixing and microfluidic configurations of high levels of realism. We highlight the capability of the method by demonstrating cases like the formation of a Taylor cone, microfluidic bubble generation, jet evolution, and droplet breakup. Results agree well with both existing experimental and computational reports.

The phenomenon of electrohydrodynamic (EHD) jetting is affected by both the flow and electric properties of the dielectric fluid. A computational fluid dynamics (CFD) approach has been used to analyse the resultant effect of fluid viscosity on EHD flows. This study looks at the unique effect of fluid viscosity on the flow profile, velocity magnitude and the electric field distribution. It is very difficult to experimentally study these relationships, but CFD provides insights that can open the world of Electrohydrodynamics to new levels of applications; as this will give an idea of how to manipulate the jet formation. Viscosity has been highlighted as one of the key parameters that aid jet elongation and stability. Therefore, the necessity to study its role. Most studies have been carried out experimentally, but this paper provides computation insights. To solve the multiphase problem, a finite volume method using the Volume of Fluid approach for capturing the shape of the interface was used for the investigation. The leaky dielectric model which describes the process solves the combination of the Charge Transport Model and Navier-Stokes equations simultaneously. The transient liquid-gas interface tracking was achieved using the VOF technique. Among many other features observed, the results showed that it takes more time for the electric field to overcome the opposing surface tension of the solution at higher viscosity than at lower viscosity. Higher electric field magnitudes/strength were observed for the fluid of lower viscosity than that of the higher viscosity. Also, an increase in the viscosity reduces the droplet size/jet diameter.