Acoustic eigenfrequencies in a spheroidal cavity with a concentric penetrable sphere

Kokkorakis, GC; Roumeliotis, JA

dc.contributor.author	Kokkorakis, GC	en
dc.contributor.author	Roumeliotis, JA	en
dc.date.accessioned	2014-03-01T01:14:22Z
dc.date.available	2014-03-01T01:14:22Z
dc.date.issued	1999	en
dc.identifier.issn	0001-4966	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/13024
dc.subject.classification	Acoustics	en
dc.subject.other	acoustics	en
dc.subject.other	article	en
dc.subject.other	frequency modulation	en
dc.subject.other	priority journal	en
dc.subject.other	sound	en
dc.subject.other	sound pressure	en
dc.subject.other	sound transmission	en
dc.title	Acoustic eigenfrequencies in a spheroidal cavity with a concentric penetrable sphere	en
heal.type	journalArticle	en
heal.identifier.primary	10.1121/1.426693	en
heal.identifier.secondary	http://dx.doi.org/10.1121/1.426693	en
heal.language	English	en
heal.publicationDate	1999	en
heal.abstract	The acoustic eigenfrequencies f(nsm) in a spheroidal cavity containing a concentric penetrable sphere are determined analytically, for both Dirichlet and Neumann conditions in the spheroidal boundary. Two different methods are used for the evaluation. In the first, the pressure field is expressed in terms of both spherical and spheroidal wave functions, connected with one another by well-known expansion formulas. In the second, a shape perturbation method, this field is expressed in terms of spherical wave functions only, while the equation of the spheroidal boundary is given in spherical coordinates. The analytical determination of the eigenfrequencies is possible when the solution is specialized to small values of h = d/(2R(2)), (h much less than 1), with d the interfocal distance of the spheroidal boundary and 2R(2) the length of its rotation axis. In this case exact, closed-form expressions are g(nsm)((2)) and g(nsm)((4)) in the resulting relation f(nsm)((h)) = f(ns)((0))[1 obtained for the expansion coefficients g + h(2)g(nsm)((2)) + h(4)g(nsm)((4)) + O(h(6))]. Analogous expressions are obtained with the use of the parameter upsilon = 1-(R2/R-2')(2), (\upsilon\much less than 1), With 2R(2)' the length of the other axis of the spheroidal boundary. Numerical results are given for various values of the parameters. (C) 1999 Acoustical Society of America. [S0001-4966(99)05803-8].	en
heal.publisher	AMER INST PHYSICS	en
heal.journalName	Journal of the Acoustical Society of America	en
dc.identifier.doi	10.1121/1.426693	en
dc.identifier.isi	ISI:000079078500011	en
dc.identifier.volume	105	en
dc.identifier.issue	3	en
dc.identifier.spage	1539	en
dc.identifier.epage	1547	en