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dc.contributor.advisorBaker, Steve
dc.contributor.advisorScandrett, Clyde L.
dc.contributor.authorNg, Kiang Chuan.
dc.dateDecember 2011
dc.date.accessioned2012-08-22T15:33:08Z
dc.date.available2012-08-22T15:33:08Z
dc.date.issued2011-12
dc.identifier.urihttp://hdl.handle.net/10945/10661
dc.description.abstractIn acoustics, the so-called Transition, or T-matrix relates the incident and scattered acoustic pressures of an object or scatterer. The T-matrix of a thin steel spherical shell in water has been determined by the COMSOL Multiphysics Finite-Element Code. The shell has an outer radius of 0.5m and a thickness of 1cm. It is driven at a frequency of 474 Hz such that ka=1 (where k is the acoustic wave number and a is the outer radius of the shell). A standing wave, represented by a spherical Bessel function, is incident onto the shell surface and the corresponding scattering coefficient is computed. The approach is divided into three portions. Firstly, a fluid-loaded rigid sphere is modeled using the Acoustic-Shell Interaction (ACSH) physics mode to examine the functionality of COMSOL. It also explores the degree of improvement when a refined fluid mesh is applied. Secondly, a thin spherical shell is modeled in the ACSH physics mode. This will examine the credibility of COMSOL to obtain accurate results based on thin shell approximation. Finally, a true 3D finite element, employing the 3D elastic theory, is created using the Acoustic-Structure Interaction (ACSI) physics mode. The resulting diagonal T-matrix elements achieved an accuracy of 0.1% relative to the analytical T-matrix. Ultimately, these results will be applicable to the modeling of the radiation from an arbitrarily densely-packed array of sonar transducers.en_US
dc.description.urihttp://archive.org/details/calculationoftra1094510661
dc.format.extentxiv, 37 p. ; 28 cm.en_US
dc.publisherMonterey, California. Naval Postgraduate Schoolen_US
dc.rightsThis publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, may not be copyrighted.en_US
dc.subject.lcshSound-waves.en_US
dc.titleCalculation of the transition matrix for the scattering of acoustic waves from a thin elastic spherical shell using the COMSOL Multiphysics Finite-Element Codeen_US
dc.contributor.departmentPhysics.
dc.description.serviceSingapore Armed Forces authoren_US
etd.thesisdegree.nameM.S. in Combat Systems Technologyen_US
etd.thesisdegree.levelMastersen_US
etd.thesisdegree.disciplineCombat Systems Technologyen_US
etd.thesisdegree.grantorNaval Postgraduate School (U.S.)en_US


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