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arXiv 1106.4079math.NAcs.NA
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大波数亥姆霍兹方程的连续内部罚有限元方法

Continuous Interior Penalty Finite Element Methods for the Helmholtz Equation with Large Wave Number

Nanjing University(南京大学)

Haijun Wu

AI总结:

针对大波数亥姆霍兹方程,提出并分析使用虚部为正的复罚参数的连续内部罚有限元方法,证明其无网格约束的稳定性并导出误差估计。

摘要:

本文针对二维和三维空间中带有一阶吸收边界条件的亥姆霍兹方程,使用分片线性多项式开发并分析了一些连续内部罚有限元方法(CIP-FEMs)。所提出方法的新颖之处在于使用具有正虚部的复罚参数。证明如果罚参数是纯虚数 $ı\ga$ 且 $0<\ga\le C$,则所提出的 CIP-FEM 是稳定的(因此适定),无需任何网格约束。此外,当 $k^3h^2\le C_0$ 时,该方法在 $H^1$ 范数下满足误差估计 $C_1kh+C_2k^3h^2$;当 $k^3h^2> C_0$ 且 $kh$ 有界时,满足 $C_1kh+\frac{C_2}{\ga}$,其中 $k$ 是波数,$h$ 是网格尺寸,$C$ 是与 $k$、$h$ 和 $\ga$ 无关的正常数。还推导了最优阶 $L^2$ 误差估计。如果罚参数是虚部为正的复数,该分析同样适用。通过取 $\ga\to 0+$,上述估计在条件 $k^3h^2\le C_0$ 下推广到线性有限元方法。数值结果验证了理论发现,表明罚参数可调以大幅减少污染误差。

英文摘要:

This paper develops and analyzes some continuous interior penalty finite element methods (CIP-FEMs) using piecewise linear polynomials for the Helmholtz equation with the first order absorbing boundary condition in two and three dimensions. The novelty of the proposed methods is to use complex penalty parameters with positive imaginary parts. It is proved that, if the penalty parameter is a pure imaginary number $ı\ga$ with $0<\ga\le C$, then the proposed CIP-FEM is stable (hence well-posed) without any mesh constraint. Moreover the method satisfies the error estimates $C_1kh+C_2k^3h^2$ in the $H^1$-norm when $k^3h^2\le C_0$ and $C_1kh+\frac{C_2}{\ga}$ when $k^3h^2> C_0$ and $kh$ is bounded, where $k$ is the wave number, $h$ is the mesh size, and the $C$'s are positive constants independent of $k$, $h$, and $\ga$. Optimal order $L^2$ error estimates are also derived. The analysis is also applied if the penalty parameter is a complex number with positive imaginary part. By taking $\ga\to 0+$, the above estimates are extended to the linear finite element method under the condition $k^3h^2\le C_0$. Numerical results are provided to verify the theoretical findings. It is shown that the penalty parameters may be tuned to greatly reduce the pollution errors.

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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