Dynamics of three-dimensional electrohydrodynamic instabilities on Taylor cone jets using a numerical approach

Abstract

Electrohydrodynamic (EHD) jets are a highly promising technology for the generation of three-dimensional micro- and nanoscale structures, but the advancement of this technology is hindered by the insufficient understanding of many aspects of its flow mechanisms, such as the whipping behavior under larger electric potentials. A fully coupled numerical simulation of the three-dimensional electrohydrodynamic jet flow is used here since non-symmetric effects govern most of their EHD regimes. By applying considerable electric capillary numbers (CaE>0.25), we capture radial instabilities that until now no other numerical simulation was able to present. A comparison against previous two-dimensional axis-symmetric and validation with experimental studies of the Taylor cone jet is initially done. An exciting gain in accuracy was obtained, having an error of around 1.101% on the morphology against experimental results. Moreover, our numerical model takes into consideration the contact angle between the surface of the nozzle and the liquid, which is shown to be a very important variable for improved accuracy in the morphologic shape of the Taylor cone. Moreover, the three-dimensional structures and flow dynamics, under different electric capillary numbers, and their connection to the instabilities of the jet are studied. We present a novel visualization of the formation of droplet generation with the receded Taylor cone and the whipping dynamics.