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arXiv 1505.03032math.NAcs.NA
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有限元法在有狄拉克源项的椭圆问题中的局部误差估计

Local Error Estimates of the Finite Element Method for an Elliptic Problem with a Dirac Source Term

Silvia Bertoluzza, Astrid Decoene, Loïc Lacouture, Sébastien Martin

AI总结:

本文研究了含狄拉克源项的椭圆问题的有限元解误差,通过局部误差估计展示H^s半范数下的准最优收敛性及H^1半范数下的最优收敛性,采用Nitsche和Schatz型误差估计、Aubin-Nitsche对偶引理弱形式及离散inf-sup条件进行理论分析。

摘要:

具有狄拉克测度的椭圆问题解不属于H1,因此有限元解的收敛性不最优。梯度网格是恢复低阶有限元在L2范数下的准最优性的标准方法。在L2半范数中已证明最优(或准最优)收敛性,其中L2半范数定义为排除奇异性的子域上的L2范数。本文展示在H^s半范数(s>0)中准最优收敛性,并在最低阶情况下在H1半范数中达到最优收敛性,于二维空间中使用准均匀网格。该问题受狄拉克测度作为物理问题简化模型的启发,高精度有限元解在奇异点处并非必需。本文结果通过局部Nitsche和Schatz型误差估计、Aubin-Nitsche对偶引理弱形式及离散inf-sup条件获得,并通过数值示例验证。

英文摘要:

The solutions of elliptic problems with a Dirac measure in right-hand side are not H1 and therefore the convergence of the finite element solutions is suboptimal. Graded meshes are standard remedy to recover quasi-optimality, namely optimality up to a log-factor, for low order finite elements in L2-norm. Optimal (or quasi-optimal for the lowest order case) convergence has been shown in L2-seminorm, where the L2-seminorm is defined as the L2-norm on a subdomain which excludes the singularity. Here we show a quasi-optimal convergence for the Hs-seminorm, s \textgreater{} 0, and an optimal convergence in H1-seminorm for the lowest order case, on a family of quasi- uniform meshes in dimension 2. This question is motivated by the use of the Dirac measure as a reduced model in physical problems, and a high accuracy at the singularity of the finite element method is not required. Our results are obtained using local Nitsche and Schatz-type error estimates, a weak version of Aubin-Nitsche duality lemma and a discrete inf-sup condition. These theoretical results are confirmed by numerical illustrations.

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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