Local Discontinuous Galerkin and Classical Finite Element Methods: Differences and Similarities

Author(s):  
Paul Castillo

In this work a quantitative and qualitative comparison of the Local Discontinuous Galerkin method and classical finite element methods applied to elliptic problems is performed. High order discretizations are considered. The methods are compared with respect to accuracy of the approximation, rates of convergence, asymptotic behavior of the spectral condition number of the stiffness matrix.

2018 ◽  
Vol 16 (1) ◽  
pp. 1091-1103 ◽  
Author(s):  
Leilei Wei ◽  
Yundong Mu

AbstractIn this paper we develop and analyze the local discontinuous Galerkin (LDG) finite element method for solving the general Lax equation. The local discontinuous Galerkin method has the flexibility for arbitrary h and p adaptivity, and allows for hanging nodes. By choosing the numerical fluxes carefully we prove stability and give an error estimate. Finally some numerical examples are computed to show the convergence order and excellent numerical performance of proposed method.


2012 ◽  
Vol 17 (4) ◽  
pp. 558-570 ◽  
Author(s):  
Zongxiu Ren ◽  
Leilei Wei ◽  
Yinnian He ◽  
Shaoli Wang

In this paper we develop and analyze an implicit fully discrete local discontinuous Galerkin (LDG) finite element method for a time-fractional Zakharov–Kuznetsov equation. The method is based on a finite difference scheme in time and local discontinuous Galerkin methods in space. We show that our scheme is unconditional stable and L 2 error estimate for the linear case with the convergence rate through analysis.


2019 ◽  
Vol 17 (07) ◽  
pp. 1950035 ◽  
Author(s):  
Mahboub Baccouch

In this paper, we present a superconvergent local discontinuous Galerkin (LDG) method for nonlinear fourth-order boundary-value problems (BVPs) of the form [Formula: see text]. We prove optimal [Formula: see text] error estimates for the solution and for the three auxiliary variables that approximate the first, second, and third-order derivatives. The order of convergence is proved to be [Formula: see text], when piecewise polynomials of degree at most [Formula: see text] are used. Our numerical experiments demonstrate optimal rates of convergence. We further prove that the derivatives of the LDG solutions are superconvergent with order [Formula: see text] toward the derivatives of Gauss–Radau projections of the exact solutions. Finally, we prove that the LDG solutions are superconvergent with order [Formula: see text] toward Gauss–Radau projections of the exact solutions. Our numerical results indicate that the numerical order of superconvergence rate is [Formula: see text]. Our proofs are valid for arbitrary regular meshes using piecewise polynomials of degree [Formula: see text] and for the classical sets of boundary conditions. Several computational examples are provided to validate the theoretical results.


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