Characteristics of an Electrohydrodynamic Jet Induced by Electrochemical Injection and Field-Enhanced Dissociation in a Blade-Plane Geometry

Abstract

Although the issue of charge formation mechanisms is a major area of interest within the field of electrohydrodynamic (EHD) flows, no attempt has been made to quantitatively investigate theoretical models from the perspective of electrode processes. This article aims to provide a novel simulation model considering both electrochemical injection and field-enhanced dissociation. The concentration-dependent Butler–Volmer (B–V) equation describing the nature of the electron transfer process is employed for the first time as a charge injection law applicable to dielectric liquids, in which the injection current density depends not only on the potential drop across the thin layer between the electrode and the outer Helmholtz plane (OHP) of the electrical double layer (EDL) but also on the concentration of the reactant next to the electrode. The results show that the electrochemical injection plays a key role in producing the flapping charge density, while the field-enhanced dissociation mechanism is vital for stabilizing the jet. The movement, amalgamation, and dissipation of vortex pairs on both sides of the charge density can be detected by the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> -criterion. The temporal evolution of the axial concentration of charges can infer the formation time of homocharge or heterocharge zones. The range and amplitude of the electric force density are in accordance with conclusion drawn by experimental studies. It is hoped that these findings can provide an original support for improving the performance of EHD pumps.