Communications on Applied Mathematics and Computation ›› 2026, Vol. 8 ›› Issue (2): 411-426.doi: 10.1007/s42967-024-00444-4

• ORIGINAL PAPERS •     Next Articles

Two-Order Superconvergent CDG Finite Element Method for the Heat Equation on Triangular and Tetrahedral Meshes

Xiu Ye1, Shangyou Zhang2   

  1. 1. Department of Mathematics, University of Arkansas at Little Rock, Little Rock, AR, 72204, USA;
    2. Department of Mathematical Sciences, University of Delaware, Newark, DE, 19716, USA
  • Received:2024-01-01 Revised:2024-05-08 Online:2026-04-07 Published:2026-04-07
  • Contact: Shangyou Zhang,E-mail:szhang@udel.edu E-mail:szhang@udel.edu

Abstract: In this paper we introduce a conforming discontinuous Galerkin (CDG) finite element method for solving the heat equation. Unlike the rest of discontinuous Galerkin (DG) methods, the numerical-flux \begin{document}$ \{\nabla u_h\cdot \textbf{n}\} $\end{document} is not introduced to the computation in the CDG method. Additionally, the numerical-trace \begin{document}$ \{ u_h \} $\end{document} is not the average \begin{document}$ (u_h|_{T_1} +u_h|_{T_2})/2 $\end{document} (or some other simple average used in other DG methods), but a lifted \begin{document}$ P_{k+1} $\end{document} polynomial from the \begin{document}$ P_k $\end{document} solution \begin{document}$ u_h $\end{document} on nearby four triangles in 2D, or eight tetrahedra in 3D. We show a two-order superconvergence in space approximation when using the CDG method with a backward Euler time discretization, on triangular and tetrahedral meshes, for solving the heat equation. Numerical tests are reported which confirm the theory.

Key words: Parabolic equations, Finite element, Conforming discontinuous Galerkin (CDG), Triangular mesh, Tetrahedral mesh

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