Communications on Applied Mathematics and Computation ›› 2022, Vol. 4 ›› Issue (2): 437-476.doi: 10.1007/s42967-021-00123-8

• ORIGINAL PAPERS • 上一篇    下一篇

Convergence and Superconvergence of the Local Discontinuous Galerkin Method for Semilinear Second-Order Elliptic Problems on Cartesian Grids

Mahboub Baccouch   

  1. Department of Mathematics, University of Nebraska at Omaha, Omaha, NE 68182, USA
  • 收稿日期:2020-09-20 修回日期:2021-01-30 出版日期:2022-06-20 发布日期:2022-04-29
  • 通讯作者: Mahboub Baccouch E-mail:mbaccouch@unomaha.edu
  • 基金资助:
    The author would like to thank the anonymous reviewers for the valuable comments and suggestions which improved the quality of the paper. This research was supported by the NASA Nebraska Space Grant (Federal Grant/Award Number 80NSSC20M0112).

Convergence and Superconvergence of the Local Discontinuous Galerkin Method for Semilinear Second-Order Elliptic Problems on Cartesian Grids

Mahboub Baccouch   

  1. Department of Mathematics, University of Nebraska at Omaha, Omaha, NE 68182, USA
  • Received:2020-09-20 Revised:2021-01-30 Online:2022-06-20 Published:2022-04-29
  • Contact: Mahboub Baccouch E-mail:mbaccouch@unomaha.edu
  • Supported by:
    The author would like to thank the anonymous reviewers for the valuable comments and suggestions which improved the quality of the paper. This research was supported by the NASA Nebraska Space Grant (Federal Grant/Award Number 80NSSC20M0112).

摘要: This paper is concerned with convergence and superconvergence properties of the local discontinuous Galerkin (LDG) method for two-dimensional semilinear second-order elliptic problems of the form -Δu=f (x, y, u) on Cartesian grids. By introducing special GaussRadau projections and using duality arguments, we obtain, under some suitable choice of numerical fuxes, the optimal convergence order in L2-norm of O(hp+1) for the LDG solution and its gradient, when tensor product polynomials of degree at most p and grid size h are used. Moreover, we prove that the LDG solutions are superconvergent with an order p + 2 toward particular Gauss-Radau projections of the exact solutions. Finally, we show that the error between the gradient of the LDG solution and the gradient of a special Gauss-Radau projection of the exact solution achieves (p + 1)-th order superconvergence. Some numerical experiments are performed to illustrate the theoretical results.

关键词: Semilinear second-order elliptic boundary-value problems, Local discontinuous Galerkin method, A priori error estimation, Optimal superconvergence, Supercloseness, Gauss-Radau projections

Abstract: This paper is concerned with convergence and superconvergence properties of the local discontinuous Galerkin (LDG) method for two-dimensional semilinear second-order elliptic problems of the form -Δu=f (x, y, u) on Cartesian grids. By introducing special GaussRadau projections and using duality arguments, we obtain, under some suitable choice of numerical fuxes, the optimal convergence order in L2-norm of O(hp+1) for the LDG solution and its gradient, when tensor product polynomials of degree at most p and grid size h are used. Moreover, we prove that the LDG solutions are superconvergent with an order p + 2 toward particular Gauss-Radau projections of the exact solutions. Finally, we show that the error between the gradient of the LDG solution and the gradient of a special Gauss-Radau projection of the exact solution achieves (p + 1)-th order superconvergence. Some numerical experiments are performed to illustrate the theoretical results.

Key words: Semilinear second-order elliptic boundary-value problems, Local discontinuous Galerkin method, A priori error estimation, Optimal superconvergence, Supercloseness, Gauss-Radau projections

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