Singh, GautamNatesan, SrinivasanSendur, Ali2026-01-242026-01-2420230020-71601029-0265https://doi.org/10.1080/00207160.2023.2166347https://hdl.handle.net/20.500.12868/5848This article focuses on constructing and analyzing a non-symmetric interior penalty Galerkin method (NIPG) on Shishkin mesh for solving singularly perturbed 2D elliptic boundary-value problems (BVPs). We use piecewise Lagrange interpolation at Gaussian points to improve the order of convergence of the interpolation error. We then study the superconvergence properties of the NIPG method and prove O(N-1 ln N)(k+1) order of convergence in the discrete energy-norm. Various numerical experiments are provided to validate the theoretical results.eninfo:eu-repo/semantics/closedAccessSingularly perturbed 2D elliptic BVPsconvection-diffusion problemShishkin meshdiscontinuous Galerkin method with interior penaltysuperconvergenceArticle10.1080/00207160.2023.216634710059489672-s2.0-85147018387Q2WOS:000918132900001Q1