Attenuation of the higherorder crosssectional modes in a duct with a thin porous layer
Publication date
2005Keyword
Acoustic intensityAcoustic wave velocity
Acoustic wave absorption
Eigenvalues and eigenfunctions
Absorbing media
Finite element analysis
Acoustic wave propagation
Acoustic waveguides
PeerReviewed
Yes
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A numerical method for sound propagation of higherorder crosssectional modes in a duct of arbitrary crosssection and boundary conditions with nonzero, complex acoustic admittance has been considered. This method assumes that the crosssection of the duct is uniform and that the duct is of a considerable length so that the longitudinal modes can be neglected. The problem is reduced to a twodimensional (2D) finite element (FE) solution, from which a set of crosssectional eigenvalues and eigenfunctions are determined. This result is used to obtain the modal frequencies, velocities and the attenuation coefficients. The 2D FE solution is then extended to threedimensional via the normal mode decomposition technique. The numerical solution is validated against experimental data for sound propagation in a pipe with inner walls partially covered by coarse sand or granulated rubber. The values of the eigenfrequencies calculated from the proposed numerical model are validated against those predicted by the standard analytical solution for both a circular and rectangular pipe with rigid walls. It is shown that the considered numerical method is useful for predicting the sound pressure distribution, attenuation, and eigenfrequencies in a duct with acoustically nonrigid boundary conditions. The purpose of this work is to pave the way for the development of an efficient inverse problem solution for the remote characterization of the acoustic boundary conditions in natural and artificial waveguides.Version
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Horoshenkov, K.V. and Yin, Y. (2005). Attenuation of the higherorder crosssectional modes in a duct with a thin porous layer. The Journal of the Acoustical Society of America. Vol.117, No. 2, pp. 528535.Link to published version
http://scitation.aip.org/journals/doc/JASMANft/vol_117/iss_2/528_1.htmlType
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