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Acoustic Scattering Cross Sections of Smart Obstacles: A Case Study

Published online by Cambridge University Press:  20 August 2015

Lorella Fatone ,
Maria Cristina Recchioni  and
Francesco Zirilli
Lorella Fatone*
Affiliation:
Dipartimento di Matematica e Informatica, Universitàdi Camerino, Via Madonna delle Carceri 9, 62032 Camerino (MC), Italy
Maria Cristina Recchioni*
Affiliation:
Dipartimento di Scienze Sociali “D. Serrani”, Università Politecnica delle Marche, Piazza Martelli 8, 60121 Ancona, Italy
Francesco Zirilli*
Affiliation:
CERI-Centro di Ricerca “Previsione Prevenzione e Controllo dei Rischi Geologici”, Università di Roma “La Sapienza”, Piazza Umberto Pilozzi 9, 00038 Valmontone (RM), Italy
*
Email:[email protected]
Email:[email protected]
Corresponding author.Email:[email protected]
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Abstract

Acoustic scattering cross sections of smart furtive obstacles are studied and discussed. A smart furtive obstacle is an obstacle that, when hit by an incoming field, avoids detection through the use of a pressure current acting on its boundary. A highly parallelizable algorithm for computing the acoustic scattering cross section of smart obstacles is developed. As a case study, this algorithm is applied to the (acoustic) scattering cross section of a “smart” (furtive) simplified version of the NASA space shuttle when hit by incoming time-harmonic plane waves, the wavelengths of which are small compared to the characteristic dimensions of the shuttle. The solution to this numerically challenging scattering problem requires the solution of systems of linear equations with many unknowns and equations. Due to the sparsity of these systems of equations, they can be stored and solved using affordable computing resources. A cross section analysis of the simplified NASA space shuttle highlights three findings: i) the smart furtive obstacle reduces the magnitude of its cross section compared to the cross section of a corresponding “passive” obstacle; ii) several wave propagation directions fail to satisfactorily respond to the smart strategy of the obstacle; iii) satisfactory furtive effects along all directions may only be obtained by using a pressure current of considerable magnitude. Numerical experiments and virtual reality applications can be found at the website: http://www.ceri.uniromal.it/ceri/zirilli/w7.

Keywords

49j2049MxxAcoustic obstacle scatteringsmart obstaclesacoustic cross sectionopen loop controloperator expansion methodwavelet expansion
Type
Research Article
Information
Communications in Computational Physics , Volume 10 , Issue 3 , September 2011 , pp. 672 - 694
Copyright
Copyright © Global Science Press Limited 2011

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