Radon transform interpretation of the Physical Optics integral and application to near and far field acoustic scattering problems

2010 ◽  
Author(s):  
H Arda Ulku ◽  
A Arif Ergin
Keyword(s):  
Radon Transform ◽  
Acoustic Scattering ◽  
Physical Optics ◽  
Far Field ◽  
Scattering Problems ◽  
Acoustic Scattering Problems

An Iterative Method for the Solution of Three-Dimensional Inverse Acoustic Scattering Problems

2002 ◽  
Author(s):  
Charbel Farhat ◽  
Radek Tezaur ◽  
Rabia Djellouli
Keyword(s):  
Domain Decomposition Method ◽  
Three Dimensional ◽  
Acoustic Scattering ◽  
Field Pattern ◽  
Far Field ◽  
Computationally Efficient ◽  
Scattering Problems ◽  
Multi Stage ◽  
Computational Methodology ◽  
Acoustic Scattering Problems

We present a computational methodology for retrieving the shape of an impenetrable obstacle from the knowledge of some acoustic far-field patterns. This methodology is based on the well-known regularized Newton algorithm, but distinguishes itself from similar optimization procedures by (a) a frequency-aware multi-stage solution strategy, (b) a computationally efficient usage of the exact sensitivities of the far-field pattern to the specified shape parameters, and (c) a numerically scalable domain decomposition method for the fast solution of three-dimensional direct acoustic scattering problems. We illustrate the salient features and highlight the performance characteristics of the proposed computational methodology with the solution on a parallel processor of various inverse mockup submarine problems.

scholarly journals Specification of Modal Participation Factors in Acoustic Scattering Problems

1993 ◽  
Vol 1 (1) ◽  
pp. 55-58
Author(s):  
M. Ettouney ◽  
R. Daddazio ◽  
F. DiMaggio
Keyword(s):  
Pressure Field ◽  
Harmonic Wave ◽  
Acoustic Scattering ◽  
Mode Shapes ◽  
Far Field ◽  
Scattering Problems ◽  
Factors Associated ◽  
Numerical Example ◽  
Structural Surface ◽  
Acoustic Scattering Problems

Using the wet modes of a submerged structure as expansion functions, it is shown how the scattered far-field pressures induced by an incident harmonic wave may be modified in a prescribed manner. This is done by applying forces directly to the structural surface, which superposes a radiated pressure field on the scattered one. By appropriate choice of the applied nodal forces, modal participation factors associated with any combination of mode shapes may be controlled. The method is illustrated by a numerical example.

Adaptivity and Three Dimensional Hierarchical Boundary Elements for Rigid Acoustic Scattering Problems

1995 ◽  
Author(s):  
Steven J. Newhouse ◽  
Ian C. Mathews
Keyword(s):  
Boundary Element ◽  
Acoustic Analysis ◽  
Three Dimensional ◽  
Acoustic Scattering ◽  
Error Estimator ◽  
Infinite Domain ◽  
Scattering Problems ◽  
Effective Form ◽  
Mesh Density ◽  
Acoustic Scattering Problems

Abstract The boundary element method is an established numerical tool for the analysis of acoustic pressure fields in an infinite domain. There is currently no well established method of estimating the surface pressure error distribution for an arbitrary three dimensional body. Hierarchical shape functions have been used as a highly effective form of p refinement in many finite and boundary element applications. Their ability to be used as an error estimator in acoustic analysis has never been fully exploited. This paper studies the influence of mesh density and interpolation order on several acoustic scattering problems. A hierarchical error estimator is implemented and its effectiveness verified against the spherical problem. A coarse cylindrical mesh is then refined using the new error estimator until the solution has converged. The effectiveness of this analysis is shown by comparing the error indicators derived during the analysis to the solution generated from a very fine cylindrical mesh.

Newton-Like Method for Solving Inverse Obstacle Acoustic Scattering Problems

2000 ◽  
Author(s):  
Rabia Djellouli ◽  
Charbel Farhat ◽  
Radek Tezaur
Keyword(s):  
Acoustic Scattering ◽  
Numerical Procedure ◽  
Decomposition Methods ◽  
Computationally Efficient ◽  
Scattering Problems ◽  
Absorbing Boundary ◽  
Element Discretization ◽  
Jacobian Matrices ◽  
Fast Solution ◽  
Acoustic Scattering Problems

Abstract A Newton-like method is designed for determining the shape or sought-after shape modifications of a scatterer from the knowledge of acoustic far-field patterns at a given number of observation points. This method distinguishes itself from existing numerical procedures by the following features: (a) exact Jacobian matrices for the linearized problems rather than approximate ones, (b) a fast numerical procedure for computing these Jacobian matrices, (c) a computationally efficient absorbing boundary condition for the finite element discretization, and (d) a numerically scalable domain decomposition methods for the fast solution of high-frequency direct acoustic scattering problems.

Marching schemes for inverse acoustic scattering problems

2005 ◽  
Vol 100 (4) ◽  
pp. 697-710 ◽  
Author(s):  
Frank Natterer ◽  
Frank Wübbeling
Keyword(s):  
Acoustic Scattering ◽  
Scattering Problems ◽  
Acoustic Scattering Problems
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