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Scattering by coupled resonating elements in air

Krynkin, A, Umnova, O, Chong, A, Taherzadeh, S and Attenborough, K 'Scattering by coupled resonating elements in air' , Journal of Physics D: Applied Physics, 44 (12) , p. 125501.

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Abstract

Scattering by (a) a single composite scatterer consisting of a concentric arrangement of an outer N-slit rigid cylinder and an inner cylinder which is either rigid or in the form of a thin elastic shell and (b) by a finite periodic array of these scatterers in air has been investigated analytically and through laboratory experiments. The composite scatterer forms a system of coupled resonators and gives rise to multiple low-frequency resonances. The corresponding analytical model employs polar angle dependent boundary conditions on the surface of the N-slit cylinder. The solution inside the slits assumes plane waves. It is shown also that in the low-frequency range the N-slit rigid cylinder can be replaced by an equivalent fluid layer. Further approximations suggest a simple square root dependence of the resonant frequencies on the number of slits and this is confirmed by data. The observed resonant phenomena are associated with Helmholtz-like behaviour of the resonator for which the radius and width of the openings are much smaller than the wavelength. The problem of scattering by a finite periodic array of such coupled resonators in air is solved using multiple scattering techniques. The resulting model predicts band-gap effects resulting from the resonances of the individual composite scatterers below the first Bragg frequency. Predictions and data confirm that use of coupled resonators results in substantial insertion loss peaks related to the resonances within the concentric configuration. In addition, for both scattering problems experimental data, predictions of the analytical approach and predictions of the equivalent fluid layer approximations are compared in the low-frequency interval.

Item Type: Article
Themes: Built and Human Environment
Energy
Subjects outside of the University Themes
Schools: Schools > School of Computing, Science and Engineering > Salford Innovation Research Centre (SIRC)
Journal or Publication Title: Journal of Physics D: Applied Physics
Publisher: Institute of Physics
Refereed: Yes
ISSN: 0022-3727
Related URLs:
Funders: Engineering and Physical Sciences Research Council (EPSRC)
Depositing User: O Umnova
Date Deposited: 10 Feb 2015 19:26
Last Modified: 29 Oct 2015 00:25
URI: http://usir.salford.ac.uk/id/eprint/33407

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