Global Superconvergence and Extrapolation of Quasi-Wilson Element Solution to Viscoelasticity Type Equations

In this paper,based on the integral identities technique of the bilinear element,higher accuracy analysis of quasi-Wilson element is discussed for the viscoelasticity type equations.Moreover,It is proved that special character of the nonconforming error of quasi-Wilson element is of order O(h3) under rectangular meshes,which leads to the superclose property of order O(h2) and the global superconvergence result in broken H1-norm by use of interpolated post-processing method.The numerical approximation solution with higher accuracy of order O(h3) is derived through constructing a proper extrapolation scheme.