Acoustic propagation in three-dimensional, rectangular ducts with flexible walls

Analytic expressions provide valuable benchmarks against which to check sophisticated finite element codes. In this talk some such expressions are presented for two duct configurations. Consideration is given first to the propagation of sound in a three-dimensional, unlined duct formed by three rigi...

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Veröffentlicht in:The Journal of the Acoustical Society of America 2010-03, Vol.127 (3_Supplement), p.1799-1799
1. Verfasser: Lawrie, Jane B.
Format: Artikel
Sprache:eng
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Zusammenfassung:Analytic expressions provide valuable benchmarks against which to check sophisticated finite element codes. In this talk some such expressions are presented for two duct configurations. Consideration is given first to the propagation of sound in a three-dimensional, unlined duct formed by three rigid walls, lying along y − 0, −b ≤ z ≤ b and z − ±b, 0 ≤ y ≤ a of a Cartesian frame reference, and closed by a thin elastic plate lying along y − a, −b ≤ z ≤ b. On assuming harmonic time dependence e−iωt, the fluid-coupled structural waves are expressed in the form Bnψn(y,z)e±isnx, n=0,1,2,…, where ψn(y,z) are an infinite set of non-separable eigenfunctions, sn are the admissible wavenumbers, and Bn are the wave amplitudes. An exact, closed form expression for the eigenfunctions is presented. Various properties of the eigensystem are discussed. Second, the effect of incorporating a porous lining into the above model is considered. It is shown how the analysis is extended to include this modification. Numerical results are presented for both situations.
ISSN:0001-4966
1520-8524
DOI:10.1121/1.3384050