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arXiv · 1007.3177

Quasi-total absorption peak by use of a backed rigid frame porous layer with circular periodic inclusions embedded

Jean-Philippe Groby·Olivier Dazel·Aroune Duclos·Laurens Boeckx·Walter Lauriks
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Abstract

The acoustic properties of a porous sheet of medium resistivity backed by a rigid plate in which are embedded a periodic set of circular inclusions is investigated. Such a structure behaves like a multi-component diffraction gratings. Numerical results show that this structure presents a quasi-total absorption peak below the essential spectrum, i.e. below the frequence of the fundamental quarter-wavelength resonance of the porous sheet in absence of inclusions. This result is explained either by the excitation of a complex trapped mode, or by the increase of viscous loss associated with a larger velocity gradient inside the layer at the modified quarter-wavelength resonance frequency. When more than one inclusion per spatial period are considered, additional quasi-total frequency peak are observed. The numerical results as calculated with the help of the mode-matching method described in the paper agree those as calculated with the help of a Finite Element method.

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Jean-Philippe Groby, Olivier Dazel, Aroune Duclos, Laurens Boeckx, Walter Lauriks. 2010-07-19. Quasi-total absorption peak by use of a backed rigid frame porous layer with circular periodic inclusions embedded. https://arxiv.org/abs/1007.3177

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