Simulation of the integral electric current characteristics of unsteady-state current passage through liquid dielectrics

The paper presents the technique for computing current-time characteristics of the transient regime, taking place after the pulsed application or change of high voltage, and dynamical current-voltage ones obtained with the voltage sawtooth modulation. The basis of the simulation is the complete set of electrohydrodynamic equations with both the convective and the migration mechanisms of charge transport being taken into account jointly. The numerical calculations were performed using commercial software package COMSOL Multiphysics based on the finite element method. The simulation was carried out for the needle-plane electrode system. The unsteady-state current passage processes, including electrohydrodynamic flow formation, were calculated. The interrelation between the latter and the total current passing through the electrical circuit were investigated. The shape and features of the current-voltage characteristics obtained with the voltage sawtooth modulation were shown to be dependent on the mechanism of charge formation. The qualitative comparison between the simulated dynamical current- voltage characteristics and the original experimental data has shown a good agreement.