摘要
本文研究了时间分布阶波方程的全离散有限元数值逼近及其高精度误差分析的新途径.首先,基于L1公式离散Caputo时间分数阶导数,构造了时间分布阶波方程的有限元全离散格式,证明了格式的无条件稳定性.然后,利用双线性元的Ritz投影算子R_h和插值算子I_h之间的高精度误差估计,再借助于插值后处理技术得到了在全离散格式下单独利用插值或投影所无法得到的超逼近和超收敛结果.进一步地,将该方法应用于变系数分布阶波方程,也证明了格式的无条件稳定性和超收敛性.最后,对一些常见的单元作了进一步探讨.
In this paper,a new approach of numerical fully discrete scheme based on the finite element approximation for the distributed order time fractional diffusion equations is developed and high accuracy error analysis is provided.Firstly,based on the L1 formula for the approximation of the time distributed order fractional derivative,the fully discrete finite element scheme is derived and the unconditional stability of the scheme is obtained.Secondly,by use of the supercolse estimate between the Ritz projection operator Rh and interpolation operator I_h of the bilinear element and the interpolated post-processing technique,the superclose and superconvergence results for the fully discrete scheme are obtained,which can't be deduced by the interpolation or Ritz projection alone.Furthermore,the proposed method is applied to the equations with variable cofficienet and the unconditional stability and superconvergent eatimates are also proved.Finally,some popular finite elements are investigated.
引文
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