Electrohydrodynamic instability at the interface between two leaky dielectric fluid layers

Abstract

The effects of an external electric field on the stability and dynamics of a planar interface between Transformer/Silicone oils (Tr/Si) layers are studied experimentally. Experiments performed in a configuration help in clarifying the effects of electrical stresses on the interface dynamics. Results demonstrate that application of electric field, higher than the critical value ( E ≥ E cr ), to the considered system enhances the spontaneous fluctuations at the interface and leads to an instability and formation of a filamentary structure at the interface. It is found that the presence of free charges made by dissociation process plays the main role in interface instability under applied electric field. Migration of the generated charge carriers drags fluid into motion and forms two counter-rotating vortices in the enclosure. Moreover, results confirm that application of electric field is an effective method for promoting mixing of two fluids, which can be helpful to step forward in design of new generation of fluid mixers here we call “ EHD Mixers”.