三维矩形域上泊松方程四面体线元的超逼近与外推

改进三角元的积分恒等式,使之适用于拟一致四面体元,借此证明了泊松方程四面体线元梯度有超逼近现象,函数值Richardson外推可以提高精度.     

椭圆型方程四面体线元的超逼近与外推

重新讨论了三角线元的积分恒等式,使之适用于三维区域的拟一致四面体元,借此证明了椭圆型方程有限元解梯度有超逼近现象,函数值Richardson外推可以提高精度.     

粘弹性方程各向异性有限元方法的超收敛分析

克服了传统有限元要求剖分网格满足正则假设(或拟一致假设)的限制,在一种新定义的各向异性网格———广义拟一致网格上,分析了粘弹性方程双线性有限元解的超逼近性质,并给出相应的超收敛结果。     

一个Crouzeix-Raviart型有限元方法关于二阶椭圆问题超逼近的一个新证明

In this paper,a new proof of superclose of a Crouzeix-Raviart type finite element is given for second order elliptic boundary value problem by Bramble-Hilbert lemma on anisotropic meshes.     

抛物积分微分问题各向异性有限元的超收敛分析

研究具有各向异性特征的双二次元对抛物积分微分方程进行了逼近.通过采用积分恒等式和插值后处理技术,在各向异性网格下得到了比以往文献高一阶的超逼近和超收敛结果.     

Superconvergence analysis of Wilson element on anisotropic meshes

The Wilson finite element method is considered to solve a class of twodimensional second order elliptic boundary value problems. By using of the particular structure of the element and some new techniques, we obtain the superclose and global superconvergence on anisotropic meshes. Numerical example is also given to confirm our theoretical analysis.     

High accuracy analysis of the characteristic‐nonconforming FEM for a convection‐dominated transport problem

A low order characteristic‐nonconforming finite element method is proposed for solving a two‐dimensional convection‐dominated transport problem. On the basis of the distinguish property of element, that is, the consistency error can be estimated as order O(h²), one order higher than that of its interpolation error, the superclose result in broken energy norm is derived for the fully discrete scheme. In the process, we use the interpolation operator instead of the so‐called elliptic projection, which is an indispensable tool in the traditional finite element analysis. Furthermore, the global superconvergence is obtained by using the interpolated postprocessing technique. Lastly, some numerical experiments are provided to verify our theoretical analysis. Copyright © 2013 John Wiley & Sons, Ltd.     

非线性四阶双曲方程的非协调有限元分析

讨论了四阶非线性双曲方程在半离散格式下的非协调有限元逼近,借助ACM单元的非协调性,得到了最优误差估计,超逼近和超收敛结果.同时利用Bramble-Hilbert引理,构造了一个新的合适的外推格式,得到了比通常收敛性高一阶的超收敛结果.     

不完全双二次元的积分展开式及其应用

导出了不完全双二次元的几个积分展开式,并利用这些积分展开式及插值后处理技巧,对Poisson方程得到了比通常误差估计高一阶的超逼近性质和整体超收敛结果.     

Superconvergence analysis and extrapolation of quasi-Wilson nonconforming finite element method for nonlinear Sobolev equations

Quasi-Wilson nonconforming finite element approximation for a class of nonlinear Sobolev equa-tions is discussed on rectangular meshes. We first prove that this element has two special characters by novel approaches. One is that (▽h ( u-Ihu )1, ▽hvh) h may be estimated as order O ( h2 ) when u ∈ H3 (Ω), where Ihu denotes the bilinear interpolation of u , vh is a polynomial belongs to quasi-Wilson finite element space and ▽h denotes the piecewise defined gradient operator, h is the mesh size tending to zero. The other is that the consistency error of this element is of order O ( h2 ) /O ( h3 ) in broken H 1-norm, which is one/two order higher than its interpolation error when u ∈ H3 (Ω) /H4 (Ω). Then we derive the optimal order error estimate and su- perclose property via mean-value method and the known high accuracy result of bilinear element. Furthermore, we deduce the global superconvergence through interpolation post processing technique. At last, an extrapola- tion result of order O ( h3 ), two order higher than traditional error estimate, is obtained by constructing a new suitable extrapolation scheme.