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A numerical model for simulating precipitation of submicrometer particles in a singlewire electrostatic precipitator is discussed in this paper. It includes all important phenomena affecting the process: electric field, space charge density, gas flow, including the secondary electrohydrodynamic flow caused by the corona discharge and charged particles, and particle transport. A simplified corona model assumes just one ionic species and neglects the ionization zone. The fully coupled model for the secondary EHD flow, considering the ion convection, has been implemented. The dust particles are charged by ionic bombardment and diffusion. The gas flow pattern is significantly modified by the secondary EHD flow, which depends on the particle concentration. As for fine particles the drift velocity is small and particles practically follow the gas streamlines, the particle concentration has a very strong effect on the precipitation efficiency. Index Terms--Corona, electrohydrodynamics, electrostatic precipitators, particle charging, particle tracking.

This paper deals with optoelectrostatic pumping of conductive liquids in microchannels. In this technique, the fluid is heated by laser irradiation and exposed to an external ac electric field. If the fluid permittivity and conductivity vary with temperature, the electric body force is generated, and pumping effect can be achieved. A numerical model of this phenomenon is presented, and it is based on the finite-element analysis of the electric, thermal, and flow fields. The numerical predictions are compared with the experimental data, with a reasonable qualitative agreement. Index Terms--Computational electrostatics, electrohydrodynamics, microfluidics, micropumping.

The effect of airflow, including the electrohydrodynamic (EHD) flow produced by the electric corona discharge, and the flow generated externally on the corona discharge has been investigated numerically in this paper. Contrary to the common assumption that the corona discharge and the EHD flow can be decoupled by neglecting the convection term in the current density equation, the equations for electric field, charge transport, and fluid flow have been solved simultaneously. The numerical algorithm is based on boundary and finite element methods, the method of characteristics, and the finite volume method. The simulation results confirm that the EHD flow has a very small effect on the corona discharge. However, in some configurations, the external airflow may have considerable effect on the I-V characteristics of the system and the current density distribution on the ground electrode. Index Terms--Computational electrostatics, electric corona discharge, electric field, electrohydrodynamic (EHD) flow.

In this paper, the electrohydrodynamic (EHD) flow in a single wire-plate electrostatic precipitator has been analyzed numerically by employing a hybrid Finite-Element Method-Method of Characteristics numerical algorithm and the commercial computational fluid dynamic software FLUENT6.2. Parameters defining both the electric and the flow fields were predicted. The interaction between the electric and the flow fields has been discussed by adopting the proposed two-way coupling algorithm. With the help of the dimensionless analysis, an entire flow regime map has been developed for different Reynolds (Re) and EHD numbers. It was found that, at very low Re (< 15) and high EHD (> 2000) (based on the corona wire) numbers, the EHD flow dominates in the channel; as Re increases, the significance of the EHD wakes gradually decreases; at a higher Re (> 50) or a lower EHD (< 500) numbers, the EHD flow becomes the near-corona-wire phenomena, and the main flow dominates the channel. The possible influence of the EHD flow on the particle-collection efficiency was also discussed. Index Terms--Corona discharge, electric field, electrohydrodynamics (EHDs), electrostatic precipitation, numerical simulation.

This paper presents a new dynamic model for the negative corona discharge in the point-plane geometry. The hybrid boundary-element-finite-element method technique is used to calculate the electric-field parameters, and the method of characteristics is employed for the charge-transport prediction. The simulation results show the charge-density distributions in the air gap and along the axis of symmetry, and the total corona current, for different voltage waveforms and parameters of the electric circuit. Index Terms--Corona discharge, electric field, finite-element method, method of characteristics (MoC), space charge.

A numerical algorithm for simulation of the electric field, generated by charged fluid in partially filled cylindrical tanks, is presented. Originally, the fluid is uniformly charged to some level, but the charge is dissipated due to volume and surface conduction. The rate of charge dissipation is calculated by solving the current continuity equation, and the electric field distribution is also evaluated at each instant of time. Both problems are solved using the finite-element method in the time domain. The results of simulation show the effect of the surface conduction on the process dynamics. Index Terms--Charge relaxation, electric field, finite-dement method (FEM), surface conduction.

Due to their good dielectric properties and low global warming potential, C4F7N–CO2 and C4F7N–N2 mixtures have shown promising potential to replace SF6 in high voltage gas insulated equipment. However, during manufacturing, installation, and transportation of power equipment, burs and metal particles can be inevitably left inside, and they can cause corona discharge. Fundamental investigation of the corona discharge mechanism is essential to monitor partial discharge signals in environmentally friendly power equipment. This paper applies the fluid model to investigate the discharge mechanism of C4F7N–CO2 and C4F7N–N2 mixtures in negative point-plane corona discharge. A 2D axisymmetric model combines the drift-diffusion equations for electrons, positive ions, and negative ions and Poisson's equation to study the process of dynamics. The gas is a mixture of C4F7N (5%, 7%, or 13%) and CO2 or N2 (95%, 93%, or 87%). The rise time of the first discharge pulse in C4F7N–CO2 and C4F7N–N2 mixtures is about 0.1 ns. The interval time between the first and the second pulse in the 5% C4F7N–95%CO2 mixture is about 1.5 times longer than that in the 5% C4F7N–95% N2 mixture. When the C4F7N content is 7% and 13%, the interval time between the first and second pulses in C4F7N–CO2 mixtures is about 2 and 3 times longer than those in C4F7N–N2 mixtures, respectively. The suppression regions in C4F7N–CO2 mixtures are larger than those in corresponding C4F7N–N2 mixtures. The total number of electrons, positive ions, and negative ions in C4F7N–CO2 mixtures is higher than that in C4F7N–N2 mixtures, while the reduced electric field in C4F7N–CO2 mixtures is smaller than that in C4F7N–N2 mixtures. [ABSTRACT FROM AUTHOR]

This paper presents a numerical algorithm to simulate the charging dynamics of high-resistivity spherical particles by the ionic bombardment in an electric field. The algorithm is based on solving the Poisson equation, governing the electric field distribution, and the differential equation expressing the charge conservation law. The Poisson equation is solved be means of the finite-element method using the triangular discretization and the first of interpolation. The finite-volume method (in a version called the donor-cell method) is used to handle the charge conservation equation. Results of simulation are also presented and they illustrate the effect of different parameters on the charging dynamics. For high-conductivity particles, the charging rate is practically identical to that given by the Pauthernier formula. Charging of high-resistivity particles leads to more complicated solutions and is much slower. Index Terms--Applied electrostatics, charge transport, electric field, ionic bombardment, particle charging.

An iterative numerical algorithm for simulating particle trajectories in the tribocharge powder-coating process is presented in this paper. The electric field distribution is determined by means of the finite-element method. The particle trajectories are predicted by integrating the differential equation of motion, resulting from the Newton equation. The density of the space charge in the powder cloud is estimated using the particle-in-cell algorithm. All problems are solved iteratively until a self-consistent solution is found for all the involved parameters. The algorithm has been applied to a few different models of the problem assuming mono- and polydispersed powders. The effect of powder parameters on the wrap-round and Faraday-cage effects has been investigated. Index Terms--Applied electrostatics, electromechanics of particles, particle-in-cell method, powder coating.