Applied Mathematics and Mechanics (English Edition) ›› 2022, Vol. 43 ›› Issue (4): 603-614.doi: https://doi.org/10.1007/s10483-022-2831-6

• Articles • Previous Articles    

Condensed Galerkin element of degree m for first-order initial-value problem with O(h2m+2) super-convergent nodal solutions

Si YUAN, Quan YUAN   

  1. Department of Civil Engineering, Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry, Tsinghua University, Beijing 100084, China
  • Received:2021-10-27 Revised:2022-02-22 Published:2022-03-29
  • Contact: Quan YUAN, E-mail:yuanq19@mails.tsinghua.edu.cn
  • Supported by:
    the National Natural Science Foundation of China (Nos.51878383 and 51378293)

Abstract: A new type of Galerkin finite element for first-order initial-value problems (IVPs) is proposed. Both the trial and test functions employ the same m-degreed polynomials. The adjoint equation is used to eliminate one degree of freedom (DOF) from the test function, and then the so-called condensed test function and its consequent condensed Galerkin element are constructed. It is mathematically proved and numerically verified that the condensed element produces the super-convergent nodal solutions of O(h2m+2), which is equivalent to the order of accuracy by the conventional element of degree m+1. Some related properties are addressed, and typical numerical examples of both linear and nonlinear IVPs of both a single equation and a system of equations are presented to show the validity and effectiveness of the proposed element.

Key words: Galerkin method, finite element method (FEM), condensed element, superconvergence, adjoint operator, initial-value problem (IVP)

2010 MSC Number: 

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