Streamer branching in transient nonuniform short gap discharges using numerical modeling

271

164

In this paper, we give a detailed review of recent work carried out on the numerical characterization of non-thermal gas discharge plasmas in air at atmospheric pressure. First, we briefly describe the theory of discharge development for dielectric barrier discharges, which is central to the production of non-equilibrium plasma, and we present a hydrodynamic model to approximate the evolution of charge densities. The model consists of the continuity equations for electrons, positive and negative ions coupled to Poisson's equation for the electric field. We then describe features of the finite element flux corrected transport algorithm, which has been developed to specifically aim for accuracy (no spurious diffusion or oscillations), efficiency (through the use of unstructured grids) and ease of extension to complex 3D geometries in the framework of the hydrodynamic model in gas discharges. We summarize the numerical work done by other authors who have applied different methods to various models and then we present highlights of our own work, which includes code validation, comparisons with existing results and modelling of radio frequency systems, dc discharges, secondary effects such as photoionization and plasma production in the presence of dielectrics. The extension of the code to 3D for more realistic simulations is demonstrated together with the adaptive meshing technique, which serves to achieve higher efficiency. Finally, we illustrate the versatility of our scheme by using it to simulate the transition from non-thermal to thermal discharges.We conclude that numerical modelling and, in particular, the extension to 3D can be used to shed new light on the processes involved with the production and control of atmospheric plasma, which plays an important role in a host of emerging technologies.

Section: Photoionization Modelmentioning

confidence: 84%

Numerical modelling of atmospheric pressure gas discharges leading to plasma production

Georghiou¹,

Papadakis²,

Morrow³

et al. 2005

271

164

“…The numerical algorithm used for the solution of the continuity equation for charges and the Navier-Stokes equations is based on the improved FE-FCT method developed by the authors and is described in its threedimensional form in [17]. The FCT method essentially uses a low order (that includes diffusion) and a higher order scheme (that is oscillatory) to reconstruct the optimal solution.…”

Section: Fe-fct Methodmentioning

confidence: 99%

Numerical analysis of the stability of the electrohydrodynamic (EHD) electroconvection between two plates

Vázquez¹,

Georghiou²,

Castellanos³

2008

The time evolution of the problem of Electrohydrodynamic (EHD) convection in a liquid between two plates is analysed numerically. The equations are nondimensionalized using the ion drift velocity and the viscous time scales. Following the non-dimensionalisation of the respective model, two different techniques have been used to describe the charge evolution, namely the Finite-Element Flux-Corrected Transport Method and the Particle-In-Cell technique. The results obtained with the two schemes, apart from showing good agreement, have revealed the appearance of a two-roll structure not described in previous works. This is investigated in detail for both strong and weak injection.

“…The numerical algorithm used for the solution of the continuity equation for charges and the Navier-Stokes equations is based on the improved FE-FCT method developed by the authors and is described in its three-dimensional form in [21]. The FCT method essentially uses a low order (that includes diffusion) and a higher order scheme (that is oscillatory) to reconstruct the optimal solution.…”

Section: Fct Methodsmentioning

confidence: 99%

“…The major drawback of PIC is the heavy computational cost as a large number of particles are needed to model realistic situations. On the other hand, the FE-FCT method was originally developed for the simulation of shock waves predominantly in fluid mechanics [18][19][20] and more recently it has been greatly improved and successfully applied in other areas such as gas discharges [21,22].…”

Section: Introductionmentioning

confidence: 99%

Characterization of injection instabilities in electrohydrodynamics by numerical modelling: comparison of particle in cell and flux corrected transport methods for electroconvection between two plates

Vázquez

Georghiou

Castellanos

2006

Numerical simulations are carried out for the characterization of injection instabilities in electrohydrodynamics and, in particular, the development of electroconvection between two parallel plates. The particle-in-cell and the finite element-flux corrected transport methods are used for the simulation of the test case, as they have proved very powerful and accurate in the solution of complex transport problems. Results are presented for unipolar injection (both strong and weak injections) between two plane electrodes immersed in a dielectric liquid, and the good agreement obtained by the two methods demonstrates not only their theoretical validity but also their practical ability to deal with transport problems in the presence of steep gradients. Some differences appear mainly in the prediction of small oscillations of the velocity and consequently of the electric current. These differences are highlighted and an explanation of their source is given.