An Adaptive Mesh Refinement Technique for Dynamics of Solids

An Adaptive Mesh Refinement Technique for Dynamics of Solids
Author: Abhishek Trivedi
Publisher:
Total Pages: 154
Release: 2007
Genre:
ISBN:

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Simulation of dynamics problems generally is heavily dependent on mesh size for convergence and accuracy. In many cases, the requirement of mesh size reaches to such proportions that the problem becomes unsolvable for the available computational resources. We perceive that such problems can be solved by refining and unrefining mesh adaptively during time stepping. Adaptive mesh refinement techniques available in popular literature are marred by various limitations, such as element-specific techniques, algorithm-specific techniques, etc. We utilize Conforming Hierarchical Refinement Methods (CHARMS) [32] for our purpose since it relies on the refinement of finite element basis instead of geometric sub-division of elements. Refinement in this fashion produces conforming meshes during adaptive mesh refinement for a wide range of elements. We improve CHARMS to incorporate time stepping problems. In order to show the effectiveness of such an algorithm, we modify an explicit Newmark solver to incorporate it within the adaptive mesh refinement framework. We perform the analysis of conservation properties of the modified algorithm to understand its limitations. Later, we demonstrate application of such development with a very practical example, simulation of an NDE experiment using ultrasonic guided waves. Details presented in [76] has shown that such a simulation would otherwise not have been possible. We further study the guided wave experiment and optimize various parameters of the algorithm to validate experimental results.

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.

Error-controlled Adaptive Finite Elements in Solid Mechanics

Error-controlled Adaptive Finite Elements in Solid Mechanics
Author: Ekkehard Ramm
Publisher: John Wiley & Sons
Total Pages: 436
Release: 2002-12-30
Genre: Technology & Engineering
ISBN: 0471496502

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Finite Element Methods are used for numerous engineering applications where numerical solutions of partial differential equations are needed. As computers can now deal with the millions of parameters used in these methods, automatic error estimation and automatic adaptation of the utilised method (according to this error estimation), has become a hot research topic. This text offers comprehensive coverage of this new field of automatic adaptation and error estimation, bringing together the work of eight outstanding researchers in this field who have completed a six year national research project within the German Science Foundation. The result is a state-of-the-art work in true reference style. Each chapter is self-contained and covers theoretical, algorithmic and software presentations as well as solved problems. A main feature consists of several carefully elaborated benchmarks of 2D- and 3D- applications. First book to go beyond the Finite Element Method in itself Covers material from a new research area Presents benchmarks of 2D- and 3D- applications Fits with the new trend for genetic strategies in engineering

Error-controlled Adaptive Finite Elements in Solid Mechanics

Error-controlled Adaptive Finite Elements in Solid Mechanics
Author: Ekkehard Ramm
Publisher: John Wiley & Sons
Total Pages: 422
Release: 2003-08-01
Genre: Technology & Engineering
ISBN: 0470857978

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Finite Element Methods are used for numerous engineering applications where numerical solutions of partial differential equations are needed. As computers can now deal with the millions of parameters used in these methods, automatic error estimation and automatic adaptation of the utilised method (according to this error estimation), has become a hot research topic. This text offers comprehensive coverage of this new field of automatic adaptation and error estimation, bringing together the work of eight outstanding researchers in this field who have completed a six year national research project within the German Science Foundation. The result is a state-of-the-art work in true reference style. Each chapter is self-contained and covers theoretical, algorithmic and software presentations as well as solved problems. A main feature consists of several carefully elaborated benchmarks of 2D- and 3D- applications. * First book to go beyond the Finite Element Method in itself * Covers material from a new research area * Presents benchmarks of 2D- and 3D- applications * Fits with the new trend for genetic strategies in engineering

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 Refinement and Nonlinear Fluid Problems

Adaptive Refinement and Nonlinear Fluid Problems
Author: Graham F. Carey
Publisher:
Total Pages: 39
Release: 1979
Genre: Finite element method
ISBN:

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The research activity deals with theory and implementation of adaptive mesh refinement for finite element analysis of linear and nonlinear problems in mechanics. The theoretical ideas are based upon the use of residuals from the equilibrium equation and associated error bounds which relate the error in the solution to these residuals. The techniques are equally applicable to finite element applications in fluid and solid mechanics. The strategy of interweaving Newton iteration and adaptive refinement appears particularly effective for the nonlinear problems examined. (Author).

Applied Computational Fluid Dynamics Techniques

Applied Computational Fluid Dynamics Techniques
Author: Rainald Löhner
Publisher: John Wiley & Sons
Total Pages: 544
Release: 2008-04-30
Genre: Science
ISBN: 9780470989661

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Computational fluid dynamics (CFD) is concerned with the efficient numerical solution of the partial differential equations that describe fluid dynamics. CFD techniques are commonly used in the many areas of engineering where fluid behavior is an important factor. Traditional fields of application include aerospace and automotive design, and more recently, bioengineering and consumer and medical electronics. With Applied Computational Fluid Dynamics Techniques, 2nd edition, Rainald Löhner introduces the reader to the techniques required to achieve efficient CFD solvers, forming a bridge between basic theoretical and algorithmic aspects of the finite element method and its use in an industrial context where methods have to be both as simple but also as robust as possible. This heavily revised second edition takes a practice-oriented approach with a strong emphasis on efficiency, and offers important new and updated material on; Overlapping and embedded grid methods Treatment of free surfaces Grid generation Optimal use of supercomputing hardware Optimal shape and process design Applied Computational Fluid Dynamics Techniques, 2nd edition is a vital resource for engineers, researchers and designers working on CFD, aero and hydrodynamics simulations and bioengineering. Its unique practical approach will also appeal to graduate students of fluid mechanics and aero and hydrodynamics as well as biofluidics.

Dynamics of Solid Structures

Dynamics of Solid Structures
Author: Georgy Viktorovich Kostin
Publisher: Walter de Gruyter GmbH & Co KG
Total Pages: 357
Release: 2017-11-20
Genre: Science
ISBN: 311051625X

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This monograph covers new variational and projection methods to study the dynamics within solid structures. To cope with the underlying initial-boundary value problems, the method of integrodifferential relations is employed. Applications and examples in physics, mechanics and control engineering range from natural vibrations or forced motions of elastic and viscoelastic bodies to heat and mass transfer processes. Contents Generalized formulations of parabolic and hyperbolic problems Variational principles in linear elasticity Variational statements in structural mechanics Ritz method for initial-boundary value problems Variational and projection techniques with semi-discretization Integrodifferential approach to eigenvalue problems Spatial vibrations of elastic beams with convex cross-sections Double minimization in optimal control problems Semi-discrete approximations in inverse dynamic problems Modeling and control in mechatronics

Patch-based Adaptive Mesh Refinement for Multimaterial Hydrodynamics

Patch-based Adaptive Mesh Refinement for Multimaterial Hydrodynamics
Author: B. Liu
Publisher:
Total Pages: 17
Release: 2005
Genre:
ISBN:

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We present a patch-based direct Eulerian adaptive mesh refinement (AMR) algorithm for modeling real equation-of-state, multimaterial compressible flow with strength. Our approach to AMR uses a hierarchical, structured grid approach first developed by (Berger and Oliger 1984), (Berger and Oliger 1984). The grid structure is dynamic in time and is composed of nested uniform rectangular grids of varying resolution. The integration scheme on the grid hierarchy is a recursive procedure in which the coarse grids are advanced, then the fine grids are advanced multiple steps to reach the same time, and finally the coarse and fine grids are synchronized to remove conservation errors during the separate advances. The methodology presented here is based on a single grid algorithm developed for multimaterial gas dynamics by (Colella et al. 1993), refined by(Greenough et al. 1995), and extended to the solution of solid mechanics problems with significant strength by (Lomov and Rubin 2003). The single grid algorithm uses a second-order Godunov scheme with an approximate single fluid Riemann solver and a volume-of-fluid treatment of material interfaces. The method also uses a non-conservative treatment of the deformation tensor and an acoustic approximation for shear waves in the Riemann solver. This departure from a strict application of the higher-order Godunov methodology to the equation of solid mechanics is justified due to the fact that highly nonlinear behavior of shear stresses is rare. This algorithm is implemented in two codes, Geodyn and Raptor, the latter of which is a coupled rad-hydro code. The present discussion will be solely concerned with hydrodynamics modeling. Results from a number of simulations for flows with and without strength will be presented.