Propagation in an elastic wedge using the virtual source technique

Abawi, Ahmad T.; Porter, Michael B.

doi:10.1121/1.4808533

Cited by 4 publications

(8 citation statements)

References 7 publications

(7 reference statements)

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“…This prediction is carried out using the equivalent source method (ESM). 5,[29][30][31] In the literature, the ESM is also referred to as the wave superposition method or the virtual source method.…”

Section: Formulations For the Prediction Of The Scattered Field Umentioning

confidence: 99%

“…[4][5][6] No matter what the method, numerically deriving the scattering properties of a complex object with a large number of internal degrees of freedom is ultimately a very costly endeavor (see Zampolli et al paper 7 and references therein). The structural Green's function or structural impedance must be modeled either with an analytical formulation for structures of simple shape or otherwise with finite element methods.…”

Section: Introductionmentioning

confidence: 99%

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Prediction of a body's structural impedance and scattering properties using correlation of random noise

Rakotonarivo

Kuperman

Williams

2013

The Journal of the Acoustical Society of America

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This paper derives a method to estimate the structural or surface impedance matrix (or equivalently the inverse of the structural Green's function) for an elastic body by placing it in an encompassing and spatially random noise field and cross-correlating pressure and normal velocity measurements taken on its surface. A numerical experiment is presented that utilizes a cross-correlation method to determine the structural impedance matrix for an infinite cylindrical shell excited by a spatially random noise field. It is shown that the correlation method produces the exact analytic form of the structural impedance matrix. Furthermore, using standard impedance formulations of the scattered and incident pressure fields at the object surface that are based on the equivalent source method and using this estimated structural impedance, a prediction of the scattered acoustic field at any position outside of the object can be made for any given incident field. An example is presented for a point (line) source near a cylindrical shell and when compared with the analytical result, excellent agreement is found between the scattered fields at a radius close to the shell.

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Section: Formulations For the Prediction Of The Scattered Field Umentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Prediction of a body's structural impedance and scattering properties using correlation of random noise

Rakotonarivo

Kuperman

Williams

2013

The Journal of the Acoustical Society of America

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“…The unknown coefficients in these equations are determined by applying the boundary conditions at the top and bottom surfaces and in the interface. The roots of the determinant of the resulting equation give the eigenvalues, k. The components of the displacement and stress tensor are computed from the potentials according to Equation (5).…”

Section: Sep 2007mentioning

confidence: 99%

Coupled Mode Propagation in Elastic Media

Abawi¹,

Porter²

2007

Self Cite

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LONG TERM GOALSDevelop an accurate and reliable range-dependent propagation model for propagation in an ocean overlying an elastic bottom based on coupled mode theory. OBJECTIVESThe objective of this effort is to develop, test and validate a range-dependent elastic propagation code by developing a coupled-mode extension to the existing elastic normal mode codes. APPROACHIn a variety of applications in shallow water acoustics, coupled mode theory is an attractive model. In addition to the parabolic equation technique (PE), it is the only other numerically efficient model that provides the solution of the wave equation in a range-dependent environment. However, while the parabolic equation technique for propagation in the ocean over a bottom modeled as a fluid has been hugely successful, up to date there is no PE model that can produce reliable results for propagation over an elastic bottom. It is the goal of this work to use elastic coupled mode theory to develop a range-dependent propagation model for waves in an ocean overlying an elastic bottom. To accomplish this goal, we plan to use the elastic coupled mode theory developed in [1], the acoustic version of which was successfully applied to the acoustic wedge in [2]. In this method, as in its acoustic counterpart, the range-dependent waveguide is divided into small stair-steps, and the field from one stair step to the next is propagated by the coupled mode differential equation, here referred to as the coupled mode engine. The coupled mode engine uses a marching technique similar to the one used in the PE method, except that in this case the grid spacing is determined by the width of the stair-steps, which is determined by the degree at which the water depth changes as a function of range. During this process, it computes the mode coupling matrices from the knowledge of the local modes and their depth derivatives. By combining the coupled mode engine with an elastic normal mode model, we plan to develop a model for propagation of waves in a range-dependent environment overlying an elastic bottom. WORK COMPLETEDAccording to the elastic coupled mode model used in our work, the displacement vector and the stress tensor are expanded in terms of local modes with coefficients that depend on range as 1

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“…The acoustic properties of rectangular rooms have also been discussed (Aretz et al, 2014;Godinho et al, 2011;Meissner, 2013). Acoustic waves propagated in wedges have been analyzed by use of various methods (Abawi, Porter, 2007; Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

“…Acoustic waves propagated in wedges have been analyzed by use of various methods (Abawi, Porter, 2007; Fig. 1. Wedge region with a sound source located at the bottom.…”

Section: Introductionmentioning

confidence: 99%

Sound Radiation from a Surface Source Located at the Bottom of the Wedge Region

Szemela¹

2015

Archives of Acoustics

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Applying rigorous analytical methods, formulas describing the sound radiation have been obtained for the wedge region bounded by two transverse baffles with a common edge and bottom. It has been assumed that the surface sound source is located at the bottom. The presented formulas can be used to calculate the sound pressure and power inside the wedge region. They are valid for any value of the wedge angle and represent a generalization of the formulas describing the sound radiation inside the two and three-wall corner region. Moreover, the presented formulas can be easily adapted for any case when more than one sound source is located at the bottom. To demonstrate their practical application, the distribution of the sound pressure modulus and the sound power have been analyzed in the case of a rectangular piston located at the wedge's bottom. The influence of the transverse baffle on the sound power has been investigated. Based on the obtained formulas, the behaviour of acoustic fields inside a wedge can be predicted.

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Propagation in an elastic wedge using the virtual source technique

Cited by 4 publications

References 7 publications

Prediction of a body's structural impedance and scattering properties using correlation of random noise

Prediction of a body's structural impedance and scattering properties using correlation of random noise

Coupled Mode Propagation in Elastic Media

Sound Radiation from a Surface Source Located at the Bottom of the Wedge Region

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