Black Box Multigrid Solver for Definite and Indefinite Problems

Black Box Multigrid Solver for Definite and Indefinite Problems PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 21

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Book Description
A two-level analysis method for certain separable problems is introduced. It motivates the definition of improved versions of Black Box Multigrid for diffusion problems with discontinuous coefficients and indefinite Helmholtz equations. For anisotropic problems, it helps in choosing suitable implementations for frequency decomposition multigrid methods. For highly indefinite problems, it provides a way to choose in advance a suitable mesh size for the coarsest grid used. Numerical experiments confirm the analysis and show the advantage of the present methods for several examples.

Black Box Multigrid Solver for Definite and Indefinite Problems

Black Box Multigrid Solver for Definite and Indefinite Problems PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 21

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Book Description
A two-level analysis method for certain separable problems is introduced. It motivates the definition of improved versions of Black Box Multigrid for diffusion problems with discontinuous coefficients and indefinite Helmholtz equations. For anisotropic problems, it helps in choosing suitable implementations for frequency decomposition multigrid methods. For highly indefinite problems, it provides a way to choose in advance a suitable mesh size for the coarsest grid used. Numerical experiments confirm the analysis and show the advantage of the present methods for several examples.

Matrix-Based Multigrid

Matrix-Based Multigrid PDF Author: Yair Shapira
Publisher: Springer Science & Business Media
ISBN: 1475737262
Category : Mathematics
Languages : en
Pages : 225

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Book Description
Many important problems in applied science and engineering, such as the Navier Stokes equations in fluid dynamics, the primitive equations in global climate mod eling, the strain-stress equations in mechanics, the neutron diffusion equations in nuclear engineering, and MRIICT medical simulations, involve complicated sys tems of nonlinear partial differential equations. When discretized, such problems produce extremely large, nonlinear systems of equations, whose numerical solution is prohibitively costly in terms of time and storage. High-performance (parallel) computers and efficient (parallelizable) algorithms are clearly necessary. Three classical approaches to the solution of such systems are: Newton's method, Preconditioned Conjugate Gradients (and related Krylov-space acceleration tech niques), and multigrid methods. The first two approaches require the solution of large sparse linear systems at every iteration, which are themselves often solved by multigrid methods. Developing robust and efficient multigrid algorithms is thus of great importance. The original multigrid algorithm was developed for the Poisson equation in a square, discretized by finite differences on a uniform grid. For this model problem, multigrid exhibits extremely rapid convergence, and actually solves the problem in the minimal possible time. The original algorithm uses rediscretization of the partial differential equation (POE) on each grid in the hierarchy of coarse grids that are used. However, this approach would not work for more complicated problems, such as problems on complicated domains and nonuniform grids, problems with variable coefficients, and non symmetric and indefinite equations. In these cases, matrix-based multi grid methods are in order.

Algebraic Multilevel Iteration Methods with Applications

Algebraic Multilevel Iteration Methods with Applications PDF Author:
Publisher:
ISBN:
Category : Differential equations, Partial
Languages : en
Pages : 152

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Book Description


SIAM Journal on Scientific Computing

SIAM Journal on Scientific Computing PDF Author:
Publisher:
ISBN:
Category : Electronic data processing
Languages : en
Pages : 780

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Book Description


The Robust Multigrid Technique

The Robust Multigrid Technique PDF Author: Sergey I. Martynenko
Publisher: Walter de Gruyter GmbH & Co KG
ISBN: 3110539268
Category : Mathematics
Languages : en
Pages : 212

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Book Description
This book presents a detailed description of a robust pseudomultigrid algorithm for solving (initial-)boundary value problems on structured grids in a black-box manner. To overcome the problem of robustness, the presented Robust Multigrid Technique (RMT) is based on the application of the essential multigrid principle in a single grid algorithm. It results in an extremely simple, very robust and highly parallel solver with close-to-optimal algorithmic complexity and the least number of problem-dependent components. Topics covered include an introduction to the mathematical principles of multigrid methods, a detailed description of RMT, results of convergence analysis and complexity, possible expansion on unstructured grids, numerical experiments and a brief description of multigrid software, parallel RMT and estimations of speed-up and efficiency of the parallel multigrid algorithms, and finally applications of RMT for the numerical solution of the incompressible Navier Stokes equations. Potential readers are graduate students and researchers working in applied and numerical mathematics as well as multigrid practitioners and software programmers. Contents Introduction to multigrid Robust multigrid technique Parallel multigrid methods Applications of multigrid methods in computational fluid dynamics

Numerical Challenges in Lattice Quantum Chromodynamics

Numerical Challenges in Lattice Quantum Chromodynamics PDF Author: Andreas Frommer
Publisher: Springer Science & Business Media
ISBN: 3642583334
Category : Mathematics
Languages : en
Pages : 197

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Book Description
Lattice gauge theory is a fairly young research area in Theoretical Particle Physics. It is of great promise as it offers the framework for an ab-initio treatment of the nonperturbative features of strong interactions. Ever since its adolescence the simulation of quantum chromodynamics has attracted the interest of numerical analysts and there is growing interdisciplinary engage ment between theoretical physicists and applied mathematicians to meet the grand challenges of this approach. This volume contains contributions of the interdisciplinary workshop "Nu merical Challenges in Lattice Quantum Chromo dynamics" that the Institute of Applied Computer Science (IAI) at Wuppertal University together with the Von-Neumann-Institute-for-Computing (NIC) organized in August 1999. The purpose of the workshop was to offer a platform for the exchange of key ideas between lattice QCD and numerical analysis communities. In this spirit leading experts from both fields have put emphasis to transcend the barriers between the disciplines. The meetings was focused on the following numerical bottleneck problems: A standard topic from the infancy of lattice QCD is the computation of Green's functions, the inverse of the Dirac operator. One has to solve huge sparse linear systems in the limit of small quark masses, corresponding to high condition numbers of the Dirac matrix. Closely related is the determination of flavor-singlet observables which came into focus during the last years.

Challenges in Scientific Computing - CISC 2002

Challenges in Scientific Computing - CISC 2002 PDF Author: Eberhard Baensch
Publisher: Springer Science & Business Media
ISBN: 3642190146
Category : Mathematics
Languages : en
Pages : 300

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Book Description
The conference Challenges In Scientific Computing (CISC 2002) took place from October, 2 to 5, 2002. The hosting institution was the Weierstrass Insti tute for Applied Analysis and Stochastics (WIAS) in Berlin, Germany. The main purpose of this meeting was to draw together researchers working in the fields of numerical analysis and scientific computing with a common interest in the numerical treatment and the computational solution of systems of nonlinear partial differential equations arising from applications of physical and engineering problems. The main focus of the conference was on the problem class of non linear transport/diffusion/reaction systems, chief amongst these being: the Navier-Stokes equations, semiconductor-device equations and porous media flow problems. The emphasis was on unsolved problems, challenging open questions from applications and assessing the various numerical methods used to handle them, rather than concentrate on accurate results from "solved" problems. Thanks to the participants it was an interesting meeting. The presentations stimulated exchanging ideas and lively discussions. This proceedings comprises 13 papers form the conference, ranging from numerical methods for flow problems, multigrid methods, semiconductor and microwave simulation, solution methods, finite element analysis to software aspects. This interesting conference would not have been possible without the help of the staff of the WIAS. I thank all participants, and all our supporters, especially those not onstage, for making the conference a success.

Efficient "black-box" Multigrid Solvers for Convection-dominated Problems

Efficient Author: Glyn Owen Rees
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Discretization Methods and Iterative Solvers Based on Domain Decomposition

Discretization Methods and Iterative Solvers Based on Domain Decomposition PDF Author: Barbara I. Wohlmuth
Publisher: Springer Science & Business Media
ISBN: 3642567673
Category : Mathematics
Languages : en
Pages : 209

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Book Description
Domain decomposition methods provide powerful and flexible tools for the numerical approximation of partial differential equations arising in the modeling of many interesting applications in science and engineering. This book deals with discretization techniques on non-matching triangulations and iterative solvers with particular emphasis on mortar finite elements, Schwarz methods and multigrid techniques. New results on non-standard situations as mortar methods based on dual basis functions and vector field discretizations are analyzed and illustrated by numerical results. The role of trace theorems, harmonic extensions, dual norms and weak interface conditions is emphasized. Although the original idea was used successfully more than a hundred years ago, these methods are relatively new for the numerical approximation. The possibilites of high performance computations and the interest in large- scale problems have led to an increased research activity.

Seventh Copper Mountain Conference on Multigrid Methods

Seventh Copper Mountain Conference on Multigrid Methods PDF Author: N. Duane Melson
Publisher:
ISBN:
Category :
Languages : en
Pages : 440

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Book Description