Theoretical analysis on electrohydrodynamic instability of a low viscous electrified jet

Abstract

In present work, a dispersion equation describing electrohydrodynamic (EHD) instability of a low viscous electrified jet was derived, where the Naiver-Stokes equations combined with the electrodynamic and hydrodynamic boundary conditions are utilized. The effect of operating parameters containing electric potential, initial jet velocity and electrode spacing on stability of the electrified jet was systematically examined and extensively analyzed, as well as liquid properties including liquid viscosity and surface tension. The analysis indicate that the axisymmetric surface waves dominate the breakup instability of the electrified jet at low electric potential or low flowrate. As flowrate or electric potential increases, the influence of the non-axisymmetric surface waves is gradually enhanced. The electrode spacing and initial diameter of the jet also have extremely slight effect on the surface wave growth rate. The viscosity could stabilize the electrified jet and almost has no influence on the maximum wave number. With the surface tension increasing, the stability of the jet is usually enhanced. The analytical results agree well with the experimental observation in the varicose instability. Meanwhile, the discrepancy between the predicted and experimental data in the whipping instability indicates the influence of non-linear perturbations is indispensable.