Download or read book Finite Element Analysis of Acoustic Scattering written by Frank Ihlenburg and published by Springer Science & Business Media. This book was released on 2006-03-29 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Effect of Ocean Surface Profiles on Near surface Steady state Acoustic Scattering written by Nathaniel Rivera and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hybrid Smoothed Finite Element Method for Two dimensional Underwater Acoustic Scattering Problems written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Acoustic Scattering from Ellipses by the Modal Element Method written by Kevin Lee Kreider and published by . This book was released on 1995 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Use of the Finite Element Method for the Modeling of Acoustic Scattering from One dimensional Rough Fluid poroelastic Interfaces written by Anthony Lucas Bonomo and published by . This book was released on 2014 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: A poroelastic finite element formulation originally derived for modeling porous absorbing material in air is adapted to the problem of acoustic scattering from a poroelastic seafloor with a one-dimensional randomly rough interface. The developed formulation is verified through calculation of the plane wave reflection coefficient for the case of a flat surface and comparison with the well known analytical solution. The scattering strengths are then obtained for two different sets of material properties and roughness parameters using a Monte Carlo approach. These numerical results are compared with those given by three analytic scattering models---perturbation theory, the Kirchhoff approximation, and the small-slope approximation---and from those calculated using two finite element formulations where the sediment is modeled as an acoustic fluid.

Download or read book Acoustic Interactions with Submerged Elastic Structures written by Ard‚shir Guran and published by World Scientific. This book was released on 2002 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt: This series of volumes constitutes an outstanding collection of contributions by the most active research workers in the area of acoustics and mechanics. It brings the reader up to date on the status of the various aspects of research in this field. The volumes should preserve their value for a long time, as they represent a monument to the achievements of human research capabilities in the underwater-acoustics aspects of the environment.

Download or read book Modal Ring Method for the Scattering of Sound written by Kenneth J. Baumeister and published by . This book was released on 1993 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Acoustic Interactions with Submerged Elastic Structures written by A. Guran and published by World Scientific. This book was released on 2001 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: The interaction of acoustic fields with submerged elastic structures, both by propagation and scattering, is being investigated at various institutions and laboratories world-wide with ever-increasing sophistication of experiments and analysis. This book offers a collection of contributions from these research centers that represent the present state-of-the-art in the study of acoustic elastic interaction, being on the cutting edge of these investigations. This includes the description of acoustic scattering from submerged elastic objects and shells by the Resonance Scattering Theory of Flax, Dragonette and berall, and the interaction of these phenomena in terms of interface waves. It also includes the use of this theory for the purpose of inverse scattering, i.e. the determination of the scattered objects properties from the received acoustic backscattered signals. The problem of acoustically excited waves in inhomogeneous and anisotropic materials, and of inhomogeneous propagating waves is considered. Vibrations and resonances of elastic shells, including shells with various kinds of internal attachments, are analyzed. Acoustic scattering experiments are described in the time domain, and on the basis of the WignerOCoVille distribution. Acoustic propagation in the water column over elastic boundaries is studied experimentally both in laboratory tanks, and in the field, and is analyzed theoretically. Ultrasonic nondestructive testing, including such aspects like probe modelling, scattering by various types of cracks, receiving probes and calibration by a side-drilled hole is also studied in details. A comprehensive picture of these complex phenomena and other aspects is presented in the book by researchers that are experts in each of these domains, giving up-to-date accounts of the field in all these aspects. Contents: Discrete Spectral Analysis for Solitary Waves (J Engelbrecht et al.); Propagation and Interaction of Waves in Nonlinear-Elastic Solids with Microstructures (V I Erofeyev); Matched Field Processing: A Powerful Tool for the Study of Oceans and Scatterers (A Tolstoy); Progress in Underwater Acoustic Modeling (P C Etter); Reflectivity Response of a Submerged Layer with Density, Sound Velocity and Absorbtion Gradients (R Carb-Fit(r)); Mathematical Aspects of Wave Phenomena in a Wave Guide with Elastic Walls and Operator Polynomials (B P Belinskiy & J P Dauer); On Some General Mathematical Properties of the System Elastic Plate OCo Acoustic Medium (B P Belinskiy); Acoustic Scattering from Finite Length Cylinders Encapped by Two Hemispheres (D Decultot et al.); Acoustic Scattering from a Circular Cylindrical Shell Immersed in Water. Generation and Reradiation of Guided Waves (F L(r)on & G Maze); The Finite Element/Boundary Element Approach to the Radiation and Scattering of Submerged Shells Including Internal Structure or Equipment (R Miller); Resonance Extraction, Phase Matching Method and the Surface Paths for Finite Elastic Cylinders (X-L Bao); Nonlinear Waves in Thermoelastic Solids Undergoing Phase Transitions (J K Knowles). Readership: Nonlinear scientists."

Download or read book Finite element analysis of wave propagation and scattering with applications to acoustic fluid structure interaction written by Frank Ihlenburg and published by . This book was released on 1997 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Amplitude Finite Element Formulation for High frequency Acoustic Scattering Problems written by Jacob Bedrossian and published by . This book was released on 2007 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Finite Element and Boundary Methods in Structural Acoustics and Vibration written by Noureddine Atalla and published by CRC Press. This book was released on 2015-04-17 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: Effectively Construct Integral Formulations Suitable for Numerical ImplementationFinite Element and Boundary Methods in Structural Acoustics and Vibration provides a unique and in-depth presentation of the finite element method (FEM) and the boundary element method (BEM) in structural acoustics and vibrations. It illustrates the principles using a

Download or read book Finite Element and Domain Decomposition Methods for Acoustic Scattering Problems written by Antonini Puppin-Macedo and published by . This book was released on 1999 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Finite Element boundary Elements Modelling of Acoustic Scattering from Viscoelastic Anechoic Structures written by Alberto Di Meglio and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This research work focuses on the analysis of multi-layered, anechoic tiles for underwater applications, especially in the field of communications. It is firstly shown how the sound absorbing properties of viscoelastic materials can be modified and enhanced by the proper use of fillers, such as lead oxide and mica. Successively, a new method for identifying the viscoelastic frequency-dependent properties of such materials from experimental data is presented. The method is based on a variational method analogous to the Hamilton Principle. It allows calculating hard-to-find properties such as the complex viscoelastic response functions and the complex Poisson ratio. After the materials properties have been determined, it is shown how they can be incorporated into the combined finite-element-boundary element method to provide accurate numerical solutions to the acoustic scattering problem. A tile made of three layers, a reflecting aluminium layer, an absorbing butyl rubber layer and a matching layer made of a regular grid of polyurethane cones is finally analysed in several scattering and geometrical configurations. The scattering patterns produced by a plane wave incident on the tile are plotted, discussed and compared with experimental data obtained from in-tank scattering measurements of a model tile.

Download or read book A Hybrid Fem T Matrix Technique for the Analysis of Acoustic Wave Scattering by Elastic Shells of Revolution written by Kumar Eswaran and published by . This book was released on 1982 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: A hybrid finite element cum T-matrix technique is introduced for the analysis of problems involving acoustic wave scattering by shells of revolution immersed in water. The concept of a mechanical impedance or receptance is used from the theory of vibrations to provide a relationship between the velocity of the shell surface and the pressure acting upon it. This relationship is introduced in the Helmholtz integral relations for the incident and scattered fields and a T-matrix for the scattering problem is derived. The mechanical impedance is calcuated by a conventional FEM technique. Numerical results are obtained for spherical shells as a check on the numerical procedure and also for a finite capped cyclindrical shell for waves incident along the rotational axes of symmetry. The comparison with the experimental results of Dr. S. Numrich and Dr. L. Dragonette of the Naval Research Laboratory is excellent. (Author).

Download or read book The Scaled Boundary Finite Element Method written by Chongmin Song and published by John Wiley & Sons. This book was released on 2018-06-19 with total page 775 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Partition of Unity Boundary Element and Finite Element Method written by Ganesh Chandrashen Diwan and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Acoustic Analysis of a Duct of Varying Cross Section with Steady Flow in One Dimension Using Finite Element Methods and Its Comparison with Circular Duct Analysis written by Gurpreet Singh Narula and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Analysis of acoustic scattering in ducts of continuously varying cross section, when compressible potential flow is passed through it, is of importance in many applications. It is the purpose of this study to develop the circular duct and the one dimensional finite element models for different ducts and to study their relative acoustic scattering characteristics. Both finite element models are developed using similar formulation techniques. The equations of motion for circular duct model are re-formulated for the one dimensional model to take the local area into account. A velocity potential formulation is used. The code developed for evaluating the velocity potential for both models uses an LU decomposition linear equation solver. A convergence test is designed for the iterative solution of the flow code to get a user-defined level of accuracy between successive iterations. The sound source at the source plane for both models is taken as a combination of positive and negative propagating modes (in the one dimensional model, however, there is only one positive and negative propagating mode). A hybrid finite element technique is developed which has modal degrees of freedom for the nodes located at the source and the exit planes and nodal degrees of freedom at the interior nodes. The range of validity of results, in terms of the power transmission coefficient, is determined for one dimensional model and compared to the circular duct model for different duct profiles, their contraction ratios, steady flow mach numbers and for a range of source frequency spanning from plane wave to multi-mode propagation. Both models are compared with an established approximate analytical solution to determine their correctness"--Abstract, leaf iii