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arXiv 0810.1475math.NAcs.NA
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大波数亥姆霍兹方程的间断伽辽金方法

Discontinuous Galerkin Methods for the Helmholtz Equation with Large Wave Number

The University of Tennessee(田纳西大学);Nanjing University(南京大学)

Xiaobing Feng, Haijun Wu

AI总结:

针对大波数亥姆霍兹方程,提出并分析了一种内罚间断伽辽金方法,证明了其无网格约束的稳定性,并给出了最优和次优误差估计。

摘要:

本文针对二维和三维中带有一阶吸收边界条件的亥姆霍兹方程,开发并分析了一些使用分段线性多项式的内罚间断伽辽金方法。证明了所提出的间断伽辽金方法在没有任何网格约束的情况下是稳定的(因此是适定的)。对于每个固定波数 $k$,在无网格约束下,推导了破碎 $H^1$ 范数中的最优阶(关于 $h$)误差估计和 $L^2$ 范数中的次优阶误差估计。当网格尺寸 $h$ 限制在预渐近区域(即 $k^2 h \gtrsim 1$)时,后一估计改进为最优阶。还进行了数值实验以衡量理论结果,并数值检验误差界中的污染效应(关于 $k$)。所提出的内罚间断伽辽金方法的新颖之处包括:首先,该方法不仅惩罚单元边上函数值的跳跃,还惩罚法向导数和切向导数的跳跃;其次,惩罚参数取为具有正虚部的复数,因此本质上和实际上对惩罚参数没有施加约束。由于亥姆霍兹问题是非厄米且不定的线性问题,正如预期,整个分析的关键和最难部分是建立数值解的稳定性估计(即先验估计)。为此,我们分析的关键是建立并利用局部版本的 Rellich 恒等式(对于拉普拉斯算子),并模仿文献 \cite{cummings00,Cummings_Feng06,hetmaniuk07} 中给出的 PDE 解的稳定性分析。

英文摘要:

This paper develops and analyzes some interior penalty discontinuous Galerkin methods using piecewise linear polynomials for the Helmholtz equation with the first order absorbing boundary condition in the two and three dimensions. It is proved that the proposed discontinuous Galerkin methods are stable (hence well-posed) without any mesh constraint. For each fixed wave number $k$, optimal order (with respect to $h$) error estimate in the broken $H^1$-norm and sub-optimal order estimate in the $L^2$-norm are derived without any mesh constraint. The latter estimate improves to optimal order when the mesh size $h$ is restricted to the preasymptotic regime (i.e., $k^2 h \gtrsim 1$). Numerical experiments are also presented to gauge the theoretical result and to numerically examine the pollution effect (with respect to $k$) in the error bounds. The novelties of the proposed interior penalty discontinuous Galerkin methods include: first, the methods penalize not only the jumps of the function values across the element edges but also the jumps of the normal and tangential derivatives; second, the penalty parameters are taken as complex numbers of positive imaginary parts so essentially and practically no constraint is imposed on the penalty parameters. Since the Helmholtz problem is a non-Hermitian and indefinite linear problem, as expected, the crucial and the most difficult part of the whole analysis is to establish the stability estimates (i.e., a priori estimates) for the numerical solutions. To the end, the cruxes of our analysis are to establish and to make use of a local version of the Rellich identity (for the Laplacian) and to mimic the stability analysis for the PDE solutions given in \cite{cummings00,Cummings_Feng06,hetmaniuk07}.

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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