Adaptive Mesh Refinement for a Finite Difference Scheme Using a Quadtree Decomposition Approach

Adaptive Mesh Refinement for a Finite Difference Scheme Using a Quadtree Decomposition Approach
Author: Nandagopalan Auviur Srinivasa
Publisher:
Total Pages:
Release: 2010
Genre:
ISBN:

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Some numerical simulations of multi-scale physical phenomena consume a significant amount of computational resources, since their domains are discretized on high resolution meshes. An enormous wastage of these resources occurs in refinement of sections of the domain where computation of the solution does not require high resolutions. This problem is effectively addressed by adaptive mesh refinement (AMR), a technique of local refinement of a mesh only in sections where needed, thus allowing concentration of effort where it is required. Sections of the domain needing high resolution are generally determined by means of a criterion which may vary depending on the nature of the problem. Fairly straightforward criteria could include comparing the solution to a threshold or the gradient of a solution, that is, its local rate of change to a threshold. While the former criterion is not particularly rigorous and hardly ever represents a physical phenomenon of interest, it is simple to implement. However, the gradient criterion is not as simple to implement as a direct comparison of values, but it is still quick and a good indicator of the effectiveness of the AMR technique. The objective of this thesis is to arrive at an adaptive mesh refinement algorithm for a finite difference scheme using a quadtree decomposition approach. In the AMR algorithm developed, a mesh of increasingly fine resolution permits high resolution computation in sub-domains of interest and low resolution in others. In this thesis work, the gradient of the solution has been considered as the criterion determining the regions of the domain needing refinement. Initial tests using the AMR algorithm demonstrate that the paradigm adopted has considerable promise for a variety of research problems. The tests performed thus far depict that the quantity of computational resources consumed is significantly less while maintaining the quality of the solution. Analysis included comparison of results obtained with analytical solutions for four test problems, as well as a thorough study of a contemporary problem in solid mechanics.

Adaptive Mesh Refinement - Theory and Applications

Adaptive Mesh Refinement - Theory and Applications
Author: Tomasz Plewa
Publisher: Springer Science & Business Media
Total Pages: 550
Release: 2005-12-20
Genre: Mathematics
ISBN: 3540270396

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Advanced numerical simulations that use adaptive mesh refinement (AMR) methods have now become routine in engineering and science. Originally developed for computational fluid dynamics applications these methods have propagated to fields as diverse as astrophysics, climate modeling, combustion, biophysics and many others. The underlying physical models and equations used in these disciplines are rather different, yet algorithmic and implementation issues facing practitioners are often remarkably similar. Unfortunately, there has been little effort to review the advances and outstanding issues of adaptive mesh refinement methods across such a variety of fields. This book attempts to bridge this gap. The book presents a collection of papers by experts in the field of AMR who analyze past advances in the field and evaluate the current state of adaptive mesh refinement methods in scientific computing.

An Adaptive Mesh-Moving and Local Refinement Method for Time-Dependent Partial Differential Equations

An Adaptive Mesh-Moving and Local Refinement Method for Time-Dependent Partial Differential Equations
Author:
Publisher:
Total Pages: 25
Release: 1990
Genre:
ISBN:

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We discuss mesh-moving, static mesh regeneration, and local mesh-refinement algorithms that can be used with a finite difference or finite element scheme to solve initial boundary value problems for vector systems of time-dependent partial differential equations in two space dimensions and time. A coarse based mesh of quadrilateral cells is moved by an algebraic mesh-movement function so as to follow and isolate spatially distinct phenomena. The local mesh-refinement method recursively divides the time step and spatial cells of the moving base mesh in regions where error indicators are high until a prescribed tolerance is satisfied. The static mesh-regeneration procedure is used to create a new base mesh when the existing one becomes to distorted. The adaptive methods have been combined with a MacCormack finite difference scheme for hyperbolic systems and an error indicator based upon estimates of the local discretization error obtained by Richardson extrapolation. Results are presented for several computational examples.

An Adaptive Mesh Algorithm for Solving Systems of Time Dependent Partial Differential Equations

An Adaptive Mesh Algorithm for Solving Systems of Time Dependent Partial Differential Equations
Author: David C. Arney
Publisher:
Total Pages: 263
Release: 1985
Genre:
ISBN:

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This thesis discusses and adaptive mesh algorithm that can be used with a finite difference or finite element scheme to solve initial-boundary value problems for vector systems of time dependent partial differential equations in two space dimensions. This algorithm combines the adaptive technique of mesh moving, static rezoning, and local mesh refinement. The nodes of a coarse mesh of quadrilateral cells are moved by a simple algebraic node movement function. The local mesh refinement method recursively divides cells of the moving coarse mesh within clustered regions that contain nodes with large error until a user prescribed error tolerance is satisfied. Keywords: Hyperbolic equations; Expert systems; and Computations.

The Scaled Boundary Finite Element Method

The Scaled Boundary Finite Element Method
Author: Chongmin Song
Publisher: John Wiley & Sons
Total Pages: 775
Release: 2018-06-19
Genre: Science
ISBN: 1119388457

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An informative look at the theory, computer implementation, and application of the scaled boundary finite element method This reliable resource, complete with MATLAB, is an easy-to-understand introduction to the fundamental principles of the scaled boundary finite element method. It establishes the theory of the scaled boundary finite element method systematically as a general numerical procedure, providing the reader with a sound knowledge to expand the applications of this method to a broader scope. The book also presents the applications of the scaled boundary finite element to illustrate its salient features and potentials. The Scaled Boundary Finite Element Method: Introduction to Theory and Implementation covers the static and dynamic stress analysis of solids in two and three dimensions. The relevant concepts, theory and modelling issues of the scaled boundary finite element method are discussed and the unique features of the method are highlighted. The applications in computational fracture mechanics are detailed with numerical examples. A unified mesh generation procedure based on quadtree/octree algorithm is described. It also presents examples of fully automatic stress analysis of geometric models in NURBS, STL and digital images. Written in lucid and easy to understand language by the co-inventor of the scaled boundary element method Provides MATLAB as an integral part of the book with the code cross-referenced in the text and the use of the code illustrated by examples Presents new developments in the scaled boundary finite element method with illustrative examples so that readers can appreciate the significant features and potentials of this novel method—especially in emerging technologies such as 3D printing, virtual reality, and digital image-based analysis The Scaled Boundary Finite Element Method: Introduction to Theory and Implementation is an ideal book for researchers, software developers, numerical analysts, and postgraduate students in many fields of engineering and science.

An Adaptive Method with Mesh Moving and Local Mesh Refinement for Time-Dependent Partial Differential Equations

An Adaptive Method with Mesh Moving and Local Mesh Refinement for Time-Dependent Partial Differential Equations
Author: David C. Arney
Publisher:
Total Pages: 56
Release: 1988
Genre:
ISBN:

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The authors discuss mesh moving, static mesh regeneration, and local mesh refinement algorithms that can be used with a finite difference or finite element scheme to solve initial-boundary value problems for vector systems of time-dependent partial differential equations in two-space dimensions and time. A coarse base mesh of quadrilateral cells is moved by an algebraic mesh movement function so that it may follow and isolate spatially distinct phenomena. The local mesh refinement method recursively divides the time step and spatial cells of the moving base mesh in regions were error indicators are high until a prescribed tolerance is satisfied. The static mesh regeneration procedure is used to create a new base mesh when the existing ones become too distorted. In order to test our adaptive algorithms, the authors implemented them in a system code with an initial mesh generator, a MacCormack finite difference scheme for hyperbolic systems, and an error indicator based upon estimates of the local discretization error obtained by Richardson extrapolation. Results are presented for several computational examples. (kr).

A 3-D Adaptive Mesh Refinement Algorithm for Multimaterial Gas Dynamics

A 3-D Adaptive Mesh Refinement Algorithm for Multimaterial Gas Dynamics
Author:
Publisher:
Total Pages: 18
Release: 1991
Genre:
ISBN:

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Adaptive Mesh Refinement (AMR) in conjunction with high order upwind finite difference methods has been used effectively on a variety of problems. In this paper we discuss an implementation of an AMR finite difference method that solves the equations of gas dynamics with two material species in three dimensions. An equation for the evolution of volume fractions augments the gas dynamics system. The material interface is preserved and tracked from the volume fractions using a piecewise linear reconstruction technique. 14 refs., 4 figs.

Adaptive Mesh Experiments for Hyperbolic Partial Differential Equations

Adaptive Mesh Experiments for Hyperbolic Partial Differential Equations
Author: David C. Arney
Publisher:
Total Pages: 34
Release: 1990
Genre:
ISBN:

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Experiments were conducted on mesh moving and local mesh refinement algorithms that are used with a finite difference scheme to solve initial-boundary value problems for vector systems of hyperbolic partial differential equations in one dimension. The mesh moving algorithms move a coarse base mesh by a mesh movement function to follow and isolate spatially distinct phenomena. The local mesh refinement method recursively divides the time step and spatial cells in regions where error indicators are high until a prescribed error tolerance is satisfied. The adaptive mesh algorithms are implemented in a code with an initial mesh generator, a MacCormack finite difference scheme, and an error estimator. Experiments are conducted for several different problems to determine the efficiency of the adaptive methods and their combinations and to gauge their effectiveness in solving one-dimensional problems. (jhd).

Handbook of Data Structures and Applications

Handbook of Data Structures and Applications
Author: Dinesh P. Mehta
Publisher: CRC Press
Total Pages: 1387
Release: 2004-10-28
Genre: Computers
ISBN: 1420035177

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Although there are many advanced and specialized texts and handbooks on algorithms, until now there was no book that focused exclusively on the wide variety of data structures that have been reported in the literature. The Handbook of Data Structures and Applications responds to the needs of students, professionals, and researchers who need a mainstream reference on data structures by providing a comprehensive survey of data structures of various types. Divided into seven parts, the text begins with a review of introductory material, followed by a discussion of well-known classes of data structures, Priority Queues, Dictionary Structures, and Multidimensional structures. The editors next analyze miscellaneous data structures, which are well-known structures that elude easy classification. The book then addresses mechanisms and tools that were developed to facilitate the use of data structures in real programs. It concludes with an examination of the applications of data structures. The Handbook is invaluable in suggesting new ideas for research in data structures, and for revealing application contexts in which they can be deployed. Practitioners devising algorithms will gain insight into organizing data, allowing them to solve algorithmic problems more efficiently.

The Finite Volume Method in Computational Fluid Dynamics

The Finite Volume Method in Computational Fluid Dynamics
Author: F. Moukalled
Publisher: Springer
Total Pages: 799
Release: 2015-08-13
Genre: Technology & Engineering
ISBN: 3319168746

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This textbook explores both the theoretical foundation of the Finite Volume Method (FVM) and its applications in Computational Fluid Dynamics (CFD). Readers will discover a thorough explanation of the FVM numerics and algorithms used for the simulation of incompressible and compressible fluid flows, along with a detailed examination of the components needed for the development of a collocated unstructured pressure-based CFD solver. Two particular CFD codes are explored. The first is uFVM, a three-dimensional unstructured pressure-based finite volume academic CFD code, implemented within Matlab. The second is OpenFOAM®, an open source framework used in the development of a range of CFD programs for the simulation of industrial scale flow problems. With over 220 figures, numerous examples and more than one hundred exercise on FVM numerics, programming, and applications, this textbook is suitable for use in an introductory course on the FVM, in an advanced course on numerics, and as a reference for CFD programmers and researchers.