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arXiv 0911.4772math.NAcs.NA
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界面问题的破碎$P_1$-非协调有限元方法分析

An Analysis of broken $P_1$-Nonconforming Finite Element Method For Interface Problems

Korea Advanced Institute of Science and Technology(韩国科学技术院)

Do Y. Kwak, K. T. Wee

AI总结:

针对二阶椭圆界面问题,提出基于破碎$P_1$-非协调线性多项式的浸入界面有限元方法,并证明$H^1$和$L^2$范数下的最优收敛阶;进一步提出混合有限体积法,避免求解鞍点问题,给出速度和压力的最优误差估计。

摘要:

我们研究求解带界面的二阶椭圆问题的一些数值方法。我们引入了一种基于'破碎'$P_1$-非协调分段线性多项式的浸入界面有限元方法,该多项式在界面三角形单元上以边平均为自由度。这些线性多项式被破碎以匹配沿界面的齐次跳跃条件,允许界面切割单元。我们证明了$H^1$和$L^2$范数下的最优收敛阶。接下来,我们在\cite{Kwak2003}引入的框架中提出了一种混合有限体积法,使用Raviart-Thomas混合有限元和这种'破碎'$P_1$-非协调元。这种混合有限体积法的优点是,一旦我们求解了对称正定压力方程(无拉格朗日乘子),速度就可以通过一个简单公式局部计算。该过程避免了求解鞍点问题。此外,我们展示了混合有限体积法中速度和压力的最优误差估计。数值结果显示了压力在$L^2$范数和破碎$H^1$范数下以及速度在$H(\Div)$范数下的最优误差阶。

英文摘要:

We study some numerical methods for solving second order elliptic problem with interface. We introduce an immersed interface finite element method based on the `broken' $P_1$-nonconforming piecewise linear polynomials on interface triangular elements having edge averages as degrees of freedom. This linear polynomials are broken to match the homogeneous jump condition along the interface which is allowed to cut through the element. We prove optimal orders of convergence in $H^1$ and $L^2$-norm. Next we propose a mixed finite volume method in the context introduced in \cite{Kwak2003} using the Raviart-Thomas mixed finite element and this `broken' $P_1$-nonconforming element. The advantage of this mixed finite volume method is that once we solve the symmetric positive definite pressure equation(without Lagrangian multiplier), the velocity can be computed locally by a simple formula. This procedure avoids solving the saddle point problem. Furthermore, we show optimal error estimates of velocity and pressure in our mixed finite volume method. Numerical results show optimal orders of error in $L^2$-norm and broken $H^1$-norm for the pressure, and in $H(\Div)$-norm for the velocity.

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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