Supercloseness of the NIPG method for a singularly perturbed convection diffusion problem on Shishkin mesh in 2D
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As a popular stabilization technique, the nonsymmetric interior penalty Galerkin (NIPG) method has significant application value in computational fluid dynamics. In this paper, we study the NIPG method for a typical two-dimensional singularly perturbed convection diffusion problem on a Shishkin mesh. According to the characteristics of the solution, the mesh and numerical scheme, a new composite interpolation is introduced. In fact, this interpolation is composed of a vertices-edges-element interpolation within the layer and a local L^2-projection outside the layer. On the basis of that, by selecting penalty parameters on different types of interelement edges, we further obtain the supercloseness of almost k+1/2 order in an energy norm. Here k is the degree of piecewise polynomials. Numerical tests support our theoretical conclusion.
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