A Robust Smoother for Convection-Diffusion Problems with Closed Characteristics |
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Authors: | Klaus Johannsen |
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Affiliation: | IWR/Technical Simulation Universit?t Heidelberg Im Neuenheimer Feld 368 D-9120 Heidelberg Germany e-mail: Klaus.Johannsen@iwr.uni-heidelberg.de http://www.iwr.uni-heidelberg.de/?Klaus.Johannsen, DE
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Abstract: | In this paper we analyze a model problem for the convection-diffusion equation where the reduced problem has closed characteristics. A full upwinding finite difference scheme is used to discretize the problem. Additionally to the strength of the convection, an arbitrary amount of crosswind-diffusion can be added on the discrete level. We present a smoother which is robust w.r.t. the strength of convection and the amount of crosswind-diffusion. It is of Gauss–Seidel type using a downwind ordering. To handle the cyclic dependencies a frequency-filtering algorithm is used. The algorithm is of nearly optimal complexity ?(n log n). It is proved that it fulfills a robust smoothing property. |
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Keywords: | AMS Subject Classifications: 65N06 65N55 |
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