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arXiv physics/0603070physics.comp-phphysics.plasm-ph
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一种用于负拖缆模拟的自适应网格加密策略

An adaptive grid refinement strategy for the simulation of negative streamers

C. Montijn, W. Hundsdorfer, U. Ebert

摘要:

在非附着气体的电击穿过程中,负流光的演化可以用电子和正离子的双流体模型来描述。它包括带电粒子在局部电场中的漂移、扩散和反应的连续性方程,耦合到电势的泊松方程。该模型产生的场增强和陡峭的传播电离前端的尖端不断增长的电离丝。本文提出了一种自适应网格加密方法来模拟这类结构。它使用有限体积空间离散化和显式时间步进,这允许从泊松方程的连续性方程的网格解耦。标准的细化方法,其中的细化标准是基于本地错误监控失败,由于拖缆前端的拉字符传播到一个线性不稳定状态。我们提出了一个细化方法,处理所有这些功能。一维流光前以及三维流光圆柱对称(因此有效的2D数值目的)的测试成功地进行。在细网格上的结果表明,这种自适应网格方法是必要的,以捕捉流光的特性。这种细化策略使我们能够充分计算纯气体中的负流光的参数制度出现的物理不稳定性:分支流光。

英文摘要:

The evolution of negative streamers during electric breakdown of a non-attaching gas can be described by a two-fluid model for electrons and positive ions. It consists of continuity equations for the charged particles including drift, diffusion and reaction in the local electric field, coupled to the Poisson equation for the electric potential. The model generates field enhancement and steep propagating ionization fronts at the tip of growing ionized filaments. An adaptive grid refinement method for the simulation of these structures is presented. It uses finite volume spatial discretizations and explicit time stepping, which allows the decoupling of the grids for the continuity equations from those for the Poisson equation. Standard refinement methods in which the refinement criterion is based on local error monitors fail due to the pulled character of the streamer front that propagates into a linearly unstable state. We present a refinement method which deals with all these features. Tests on one-dimensional streamer fronts as well as on three-dimensional streamers with cylindrical symmetry (hence effectively 2D for numerical purposes) are carried out successfully. Results on fine grids are presented, they show that such an adaptive grid method is needed to capture the streamer characteristics well. This refinement strategy enables us to adequately compute negative streamers in pure gases in the parameter regime where a physical instability appears: branching streamers.

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