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arXiv 0904.1885math.NAcs.NAmath.AP
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高对比度扩散方程单元中心有限体积离散的鲁棒多重网格预处理器

Robust multigrid preconditioners for cell-centered finite volume discretization of the high-contrast diffusion equation

Louisiana State University(路易斯安那州立大学)

Burak Aksoylu, Zuhal Yeter

AI总结:

针对高对比度扩散方程的守恒五点单元中心有限体积离散,通过扩展奇异摄动分析证明并数值验证了Aksoylu等人提出的预处理器的鲁棒性,该预处理器对系数对比度和网格尺寸同时鲁棒,且性能独立于延拓算子和光滑子。

摘要:

我们研究了高对比度扩散方程的守恒五点单元中心有限体积离散。我们的目标是构建对系数对比度大小和网格尺寸同时鲁棒的预处理器。为此,我们通过将设计的奇异摄动分析从线性有限元离散扩展到上述离散,证明并数值验证了Aksoylu等人(2008, Comput. Vis. Sci. 11, pp. 319--331)提出的预处理器的鲁棒性。奇异摄动分析比有限元更复杂,因为离散矩阵中的所有子块都依赖于扩散系数。然而,这种依赖关系在渐近意义上被消除。这使得相同的预处理器能够被利用,因为子矩阵具有相似的极限行为;从而缩小了可用于不同离散的预处理器族——这是一个理想的预处理器设计目标。我们将数值结果与标准单元中心多重网格进行比较,观察到我们的预处理器的性能与所使用的延拓算子和光滑子无关。作为附带结果,我们还证明了高扩散岛上的解渐近地变为常数。将这种对底层PDE的定性理解整合到我们的预处理器中是其优越性能的主要原因。对角缩放可能是高对比度系数最基本的预处理器。通过扩展Graham和Hagger引入的基于矩阵条目的谱分析,我们严格证明了对角缩放矩阵的小特征值的数量取决于构成高扩散区域的孤立岛的数量。

英文摘要:

We study a conservative 5-point cell-centered finite volume discretization of the high-contrast diffusion equation. We aim to construct preconditioners that are robust with respect to the magnitude of the coefficient contrast and the mesh size simultaneously. For that, we prove and numerically demonstrate the robustness of the preconditioner proposed by Aksoylu et al. (2008, Comput. Vis. Sci. 11, pp. 319--331) by extending the devised singular perturbation analysis from linear finite element discretization to the above discretization. The singular perturbation analysis is more involved than that of finite element because all the subblocks in the discretization matrix depend on the diffusion coefficient. However, that dependence is eliminated asymptotically. This allows the same preconditioner to be utilized due to similar limiting behaviours of the submatrices; leading to a narrowing family of preconditioners that can be used for different discretizations--a desirable preconditioner design goal. We compare our numerical results to standard cell-centered multigrid and observe that performance of our preconditioner is independent of the utilized prolongation operators and smoothers. As a side result, we also prove that the solution over the highly-diffusive island becomes constant asymptotically. Integration of this qualitative understanding of the underlying PDE to our preconditioner is the main reason behind its superior performance. Diagonal scaling is probably the most basic preconditioner for high-contrast coefficients. Extending the matrix entry based spectral analysis introduced by Graham and Hagger, we rigorously show that the number of small eigenvalues of the diagonally scaled matrix depends on the number of isolated islands comprising the highly-diffusive region.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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