arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2107.07945math.NAcs.NA
收藏

块多重网格方法中基于符号的收敛性分析及其在Stokes问题中的应用

Symbol based Convergence Analysis in Block Multigrid Methods with Applications for Stokes Problems

Marco Donatelli, Matthias Bolten, Paola Ferrari, Isabella Furci

AI总结:

针对对称不定鞍点结构线性系统的多重网格收敛分析难题,提出基于生成符号的块Toeplitz结构收敛分析方法,构建收敛速率与矩阵规模无关的代数多重网格法,并在Stokes问题离散矩阵上验证了有效性。

摘要:

本文主要研究具有特殊鞍点结构的大型线性系统的高效多重网格方法。实际上,当系统矩阵对称但不定时,通常用于证明多重网格收敛性的变分收敛理论无法直接应用。不过,已有不同的代数方法可对经过适当预处理的鞍点问题进行分析,证明两层网格方法的收敛性。尤其当系数矩阵的子块具有Toeplitz或循环结构时,该方法十分高效。此时,我们可以借助相关生成符号推导收敛的充分条件,并为鞍点问题的预处理提供最优参数。\n本文针对具有隐式块Toeplitz结构的问题,提出了一种基于符号的收敛性分析方法。这类问题可通过研究其关联生成函数f的性质来分析,该生成函数是一个矩阵值函数,其维数取决于问题的块大小。在数值实验中,我们重点研究了由Stokes问题有限元离散得到的矩阵序列。通过分析所得矩阵序列隐含的9×9块多层结构,我们验证了该方法的有效性。此外,我们还提出了一种高效的代数多重网格方法,其收敛速率与矩阵规模无关。最后,我们通过多组数值实验,将所提方法的结果与当前最优策略进行了对比。

英文摘要:

The main focus of this paper is the study of efficient multigrid methods for large linear systems with a particular saddle-point structure. Indeed, when the system matrix is symmetric, but indefinite, the variational convergence theory that is usually used to prove multigrid convergence cannot be directly applied. However, different algebraic approaches analyze properly preconditioned saddle-point problems, proving convergence of the Two-Grid method. In particular, this is efficient when the blocks of the coefficient matrix possess a Toeplitz or circulant structure. Indeed, it is possible to derive sufficient conditions for convergence and provide optimal parameters for the preconditioning of the saddle-point problem in terms of the associated generating symbols. In this paper, we propose a symbol-based convergence analysis for problems that have a hidden block Toeplitz structure. Then, they can be investigated focusing on the properties of the associated generating function f, which consequently is a matrix-valued function with dimension depending on the block size of the problem. As numerical tests we focus on the matrix sequence stemming from the finite element approximation of the Stokes problem. We show the efficiency of the methods studying the hidden 9-by-9 block multilevel structure of the obtained matrix sequence. Moreover, we propose an efficient algebraic multigrid method with convergence rate independent of the matrix size. Finally, we present several numerical tests comparing the results with state-of-the-art strategies.

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。

↑