Finite Element Analysis of Acoustic Scattering

Author: Frank Ihlenburg
Publisher: Springer Science & Business Media
ISBN: 0387227008
Format: PDF, ePub, Docs
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A cognitive journey towards the reliable simulation of scattering problems using finite element methods, with the pre-asymptotic analysis of Galerkin FEM for the Helmholtz equation with moderate and large wave number forming the core of this book. Starting from the basic physical assumptions, the author methodically develops both the strong and weak forms of the governing equations, while the main chapter on finite element analysis is preceded by a systematic treatment of Galerkin methods for indefinite sesquilinear forms. In the final chapter, three dimensional computational simulations are presented and compared with experimental data. The author also includes broad reference material on numerical methods for the Helmholtz equation in unbounded domains, including Dirichlet-to-Neumann methods, absorbing boundary conditions, infinite elements and the perfectly matched layer. A self-contained and easily readable work.

Numerical Simulations in Room Acoustics Using Direct Coupling Techniques and Finite Elements

Author: Martina Pospiech
Publisher: Logos Verlag Berlin GmbH
ISBN: 3832531394
Format: PDF
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This thesis presents a coupling approach for time-harmonic problems in linear room acoustics. Therein the closed acoustic system is subdivided into air, sound source and different boundary components. The sound field of each air component is approximated with the help of modal basis functions and continuous transitions between single components are enabled by enforcing coupling conditions. Coupling to realistic boundary conditions is realized by wavenumber- and frequency-dependent impedance functions for plate-like sound absorbers. Afterwards the solution is computed by minimizing the energy based on Hamilton's Principle. For computing the basis functions and the energies of the components the Spectral Finite Element Method and the adapted Patch Recovery Method are applied. Finally numerical benchmark-simulations show the applications of this coupling approach.

Modern Solvers for Helmholtz Problems

Author: Domenico Lahaye
Publisher: Birkhäuser
ISBN: 3319288326
Format: PDF, Kindle
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This edited volume offers a state of the art overview of fast and robust solvers for the Helmholtz equation. The book consists of three parts: new developments and analysis in Helmholtz solvers, practical methods and implementations of Helmholtz solvers, and industrial applications. The Helmholtz equation appears in a wide range of science and engineering disciplines in which wave propagation is modeled. Examples are: seismic inversion, ultrasone medical imaging, sonar detection of submarines, waves in harbours and many more. The partial differential equation looks simple but is hard to solve. In order to approximate the solution of the problem numerical methods are needed. First a discretization is done. Various methods can be used: (high order) Finite Difference Method, Finite Element Method, Discontinuous Galerkin Method and Boundary Element Method. The resulting linear system is large, where the size of the problem increases with increasing frequency. Due to higher frequencies the seismic images need to be more detailed and, therefore, lead to numerical problems of a larger scale. To solve these three dimensional problems fast and robust, iterative solvers are required. However for standard iterative methods the number of iterations to solve the system becomes too large. For these reason a number of new methods are developed to overcome this hurdle. The book is meant for researchers both from academia and industry and graduate students. A prerequisite is knowledge on partial differential equations and numerical linear algebra.

Finite Element Methods for Maxwell s Equations

Author: Peter Monk
Publisher: Oxford University Press
ISBN: 9780198508885
Format: PDF
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The emphasis in on finite element methods for scattering problems that involve the solution of Maxwell's equations on infinite domains. Suitable variational formulations are developed and justified mathematically. An error analysis of edge finite element methods that are particularly well suited to Maxwell's equations is the main focus of the book.

Inverse Acoustic and Electromagnetic Scattering Theory

Author: David Colton
Publisher: Springer Science & Business Media
ISBN: 9783540628385
Format: PDF, Mobi
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This book is devoted to the mathematical and numerical analysis of the inverse scattering problem for acoustic and electromagnetic waves. The second edition includes material on Newton’s method for the inverse obstacle problem, an elegant proof of uniqueness for the inverse medium problem, a discussion of the spectral theory of the far field operator and a method for determining the support of an inhomogeneous medium from far field data.

Linear Integral Equations

Author: Rainer Kress
Publisher: Springer Science & Business Media
ISBN: 1461495938
Format: PDF
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This book combines theory, applications, and numerical methods, and covers each of these fields with the same weight. In order to make the book accessible to mathematicians, physicists, and engineers alike, the author has made it as self-contained as possible, requiring only a solid foundation in differential and integral calculus. The functional analysis which is necessary for an adequate treatment of the theory and the numerical solution of integral equations is developed within the book itself. Problems are included at the end of each chapter. For this third edition in order to make the introduction to the basic functional analytic tools more complete the Hahn–Banach extension theorem and the Banach open mapping theorem are now included in the text. The treatment of boundary value problems in potential theory has been extended by a more complete discussion of integral equations of the first kind in the classical Holder space setting and of both integral equations of the first and second kind in the contemporary Sobolev space setting. In the numerical solution part of the book, the author included a new collocation method for two-dimensional hypersingular boundary integral equations and a collocation method for the three-dimensional Lippmann-Schwinger equation. The final chapter of the book on inverse boundary value problems for the Laplace equation has been largely rewritten with special attention to the trilogy of decomposition, iterative and sampling methods Reviews of earlier editions: "This book is an excellent introductory text for students, scientists, and engineers who want to learn the basic theory of linear integral equations and their numerical solution." (Math. Reviews, 2000) "This is a good introductory text book on linear integral equations. It contains almost all the topics necessary for a student. The presentation of the subject matter is lucid, clear and in the proper modern framework without being too abstract." (ZbMath, 1999)

Computational Acoustics of Noise Propagation in Fluids Finite and Boundary Element Methods

Author: Steffen Marburg
Publisher: Springer Science & Business Media
ISBN: 9783540774488
Format: PDF, Docs
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The book provides a survey of numerical methods for acoustics, namely the finite element method (FEM) and the boundary element method (BEM). It is the first book summarizing FEM and BEM (and optimization) for acoustics. The book shows that both methods can be effectively used for many other cases, FEM even for open domains and BEM for closed ones. Emphasis of the book is put on numerical aspects and on treatment of the exterior problem in acoustics, i.e. noise radiation.