A fast-convergent spectral-fem for harmonic wave propagation in inhomogeneous layered waveguides

Belibassakis, KA; Papathanasiou, TK; Filopoulos, SP

dc.contributor.author	Belibassakis, KA	en
dc.contributor.author	Papathanasiou, TK	en
dc.contributor.author	Filopoulos, SP	en
dc.date.accessioned	2014-03-01T02:53:32Z
dc.date.available	2014-03-01T02:53:32Z
dc.date.issued	2012	en
dc.identifier.issn	10986189	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/36393
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-84866107421&partnerID=40&md5=34e382993b3cb5d6bbc9b6eb68d7abd6	en
dc.subject	Finite elements	en
dc.subject	Local-mode series	en
dc.subject	Non-uniform waveguides	en
dc.subject	Spectral methods	en
dc.subject	Stratified waveguides	en
dc.title	A fast-convergent spectral-fem for harmonic wave propagation in inhomogeneous layered waveguides	en
heal.type	conferenceItem	en
heal.publicationDate	2012	en
heal.abstract	A fast-convergent spectral model is presented for harmonic wave propagation and scattering problems in stratified, non uniform waveguides, governed by the Helmholtz equation. The method is based on a local mode series expansion, obtained by utilizing variable crosssection eigenfunction systems, which are defined through the solution of eigenvalue problems formulated along the waveguide, and including additional modes accounting for the effects of inhomogeneous boundaries and/or interfaces. The additional modes provide an implicit summation of the slowly convergent part of the local-mode series, rendering the remaining part to be fast convergent, increasing the efficiency of the method, especially in long-range propagation applications. Using the enhanced representation, in conjunction with an energy-type variational principle, a coupled-mode system of equations is derived for the determination of the unknown modal-amplitude functions. In order to treat the local vertical eigenvalue problems in the case of multilayered waveguides h- and p- Finite Element Methods have been applied exhibiting robustness and good rates of convergence. On the basis of the above, the coefficients of the coupled-mode system are calculated by numerical integration. Finally, the solution of the present coupled-mode system is obtained by using a finite difference scheme based on a uniform grid and using second-order central differences to approximate derivatives. Numerical examples are presented in simple 2D acoustic propagation problems, illustrating the role and significance of the additional mode(s) and the efficiency of the present model, that can be naturally extended to treat propagation and scattering problems in more complicated 3D waveguides. Copyright © 2012 by the International Society of Offshore and Polar Engineers (ISOPE).	en
heal.journalName	Proceedings of the International Offshore and Polar Engineering Conference	en
dc.identifier.spage	479	en
dc.identifier.epage	486	en