In this paper, we consider the cascadic multigrid method for the mortar P1 nonconforming element which is used to solve the Poisson equation and prove that the cascadic conjugate gradient method is accurate with optim...
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In this paper, we consider the cascadic multigrid method for the mortar P1 nonconforming element which is used to solve the Poisson equation and prove that the cascadic conjugate gradient method is accurate with optimal complexity.
The purpose of this paper is to study the cascadic multigrid method for the secondorder elliptic problems with curved boundary in two-dimension which are discretized by the isoparametric finite element method with num...
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The purpose of this paper is to study the cascadic multigrid method for the secondorder elliptic problems with curved boundary in two-dimension which are discretized by the isoparametric finite element method with numerical integration. We show that the CCG method is accurate with optimal complexity and traditional multigrid smoother (likesymmetric Gauss-Seidel, SSOR or damped Jacobi iteration) is accurate with suboptimal complexity.
In this paper, a cascadic multigrid method for P-1-nonconforming quadrilateral finite element approximation of second order elliptic problem is studied. A new intergrid transfer operator is constructed to connect the ...
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In this paper, a cascadic multigrid method for P-1-nonconforming quadrilateral finite element approximation of second order elliptic problem is studied. A new intergrid transfer operator is constructed to connect the nonnested coarse and fine grid spaces. We show that the cascadic multigrid method is accurate with optimal complexity for conjugate gradient smoother, and suboptimal complexity for some other traditional multigrid smoothers. Finally, some numerical experiments are reported to support the theory.
We present a red-black skewed extrapolation cascadicmultigrid (SkECMG) method to solve the Poisson equation in two dimensions based on the modified standard and skewed five-point finite difference discretization. Wit...
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We present a red-black skewed extrapolation cascadicmultigrid (SkECMG) method to solve the Poisson equation in two dimensions based on the modified standard and skewed five-point finite difference discretization. With the help of the extrapolation technique, we develop a new extrapolation operator. Applying this proposed extrapolation operator for the second-order finite difference solutions on the current and previous coarse grid, we can design a fourth-order initial value for the iterative solver on the next finer grid. The red-black Gauss-Seidel method is adopted as a smoother which is conducive to parallel implementation. Moreover, we discuss a new sifting method as a stopping criterion to reduce the number of smoothing iterations. The numerical experiment is conducted on the square domain to verify that our SkECMG algorithm can achieve high efficiency and keep less cost simultaneously.
A cascadicmultigrid (CMG) method for elliptic problems with strong material jumps is proposed and analyzed. Non-matching grids at interfaces between subdomains are allowed and treated by mortar elements. The arising ...
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A cascadicmultigrid (CMG) method for elliptic problems with strong material jumps is proposed and analyzed. Non-matching grids at interfaces between subdomains are allowed and treated by mortar elements. The arising saddle point problems are solved by a subspace confined conjugate gradient method as smoother for the CMG. Details of algorithmic realization including adaptivity are elaborated. Numerical results illustrate the efficiency of the new subspace CMG algorithm.
作者:
Pan, KejiaHe, DongdongHu, HonglingRen, ZhengyongCent S Univ
Sch Math & Stat Changsha 410083 Hunan Peoples R China Tongji Univ
Sch Aerosp Engn & Appl Mech Shanghai 200092 Peoples R China Hunan Normal Univ
Coll Math & Comp Sci Minist Educ China Key Lab High Performance Comp & Stochast Informat Changsha 410081 Hunan Peoples R China Cent S Univ
Sch Geosci & Infophys Changsha 410083 Hunan Peoples R China Cent S Univ
Minist Educ Key Lab Metallogen Predict Nonferrous Met & Geol Changsha 410083 Hunan Peoples R China
In this paper, we develop a new extrapolation cascadic multigrid method, which makes it possible to solve three dimensional elliptic boundary value problems with over 100 million unknowns on a desktop computer in half...
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In this paper, we develop a new extrapolation cascadic multigrid method, which makes it possible to solve three dimensional elliptic boundary value problems with over 100 million unknowns on a desktop computer in half a minute. First, by combining Richardson extrapolation and quadratic finite element (FE) interpolation for the numerical solutions on two-level of grids (current and previous grids), we provide a quite good initial guess for the iterative solution on the next finer grid, which is a third-order approximation to the FE solution. And the resulting large linear system from the FE discretization is then solved by the Jacobi-preconditioned conjugate gradient (JCG) method with the obtained initial guess. Additionally, instead of performing a fixed number of iterations as used in existing cascadic multigrid methods, a relative residual tolerance is introduced in the JCG solver, which enables us to obtain conveniently the numerical solution with the desired accuracy. Moreover, a simple method based on the midpoint extrapolation formula is proposed to achieve higher-order accuracy on the finest grid cheaply and directly. Test results from four examples including two smooth problems with both constant and variable coefficients, an H3-regular problem as well as an anisotropic problem are reported to show that the proposed method has much better efficiency compared to the classical V-cycle and W-cycle multigridmethods. Finally, we present the reason why our method is highly efficient for solving these elliptic problems. (C) 2017 Elsevier Inc. All rights reserved.
A cascadic multigrid method for semilinear elliptic problem is analysed. It has been proved that the algorithm has optimal order of convergence in energy norm and quasi-optimal computational complexity under more gene...
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A cascadic multigrid method for semilinear elliptic problem is analysed. It has been proved that the algorithm has optimal order of convergence in energy norm and quasi-optimal computational complexity under more general conditions. (C) 2003 Elsevier Inc. All rights reserved.
In this paper, we analyze a cascadic multigrid method for semilinear elliptic problems in which the derivative of the semilinear term is Holder continuous. We first investigate the standard finite element error estima...
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In this paper, we analyze a cascadic multigrid method for semilinear elliptic problems in which the derivative of the semilinear term is Holder continuous. We first investigate the standard finite element error estimates of this kind of problem. We then solve the corresponding discrete problems using the cascadic multigrid method. We prove that the algorithm has an optimal order of convergence in energy norm and quasi-optimal computational complexity. We also report some numerical results to support the theory.
In this paper, by using a modulus-based matrix splitting method as a smoother, a new modulus-based cascadic multigrid method is presented for solving elliptic variational inequality problems. Convergence of the new me...
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In this paper, by using a modulus-based matrix splitting method as a smoother, a new modulus-based cascadic multigrid method is presented for solving elliptic variational inequality problems. Convergence of the new method is analyzed. Numerical experiments confirm the theoretical analysis and show the efficiency of the proposed method.
An efficient extrapolation cascadic multigird (EXCMG) method is developed to solve large linear systems resulting from edge element discretizations of 3D H(curl)\documentclass[12pt]{minimal} \usepackage{amsmath} \usep...
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An efficient extrapolation cascadic multigird (EXCMG) method is developed to solve large linear systems resulting from edge element discretizations of 3D H(curl)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$H(\textbf{curl})$$\end{document} problems on rectangular meshes. By treating edge unknowns as defined on the midpoints of edges, following the similar idea of the nodal EXCMG method, we design a new prolongation operator for 3D edge-based discretizations, which is used to construct a high-order approximation to the finite element solution on the refined grid. This good initial guess greatly reduces the number of iterations required by the multigrid smoother. Furthermore, the divergence correction technique is employed to further speed up the convergence of the multigridmethod. Numerical examples including problems with high-contrast discontinuous coefficients are presented to validate the effectiveness of the proposed EXCMG method. The edge-based EXCMG method is more efficient than the auxiliary-space Maxwell solver (AMS) for definite problems in the considered geometrical configuration, and it can also efficiently solve large-scale indefinite problems encountered in engineering and scientific fields.
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