A mathematical and numerical framework for gradient meta-surfaces built upon periodically repeating arrays of Helmholtz resonators
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Date
2020-09
Publication Type
Journal Article
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Abstract
In this paper a mathematical model is given for the scattering of an incident wave from a surface covered with microscopic small Helmholtz resonators, which are cavities with small openings. More precisely, the surface is built upon a finite number of Helmholtz resonators in a unit cell and that unit cell is repeated periodically. To solve the scattering problem, the mathematical framework elaborated in Ammari et al. (2019) is used. The main result is an approximate formula for the scattered wave in terms of the lengths of the openings. Our framework provides analytic expressions for the scattering wave vector and angle and the phase-shift. It justifies the apparent absorption. Moreover, it shows that at specific lengths for the openings and a specific frequency there is an abrupt shift of the phase of the scattered wave due to the subwavelength resonances of the Helmholtz resonators. A numerically fast implementation is given to identify a region of those specific values of the openings and the frequencies.
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published
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Volume
97
Pages / Article No.
102614
Publisher
Elsevier
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Subject
Gradient meta-surface; Subwavelength resonance; Helmholtz resonator; Apparent full transmission and absorption; Abrupt phase-shift
Organisational unit
09504 - Ammari, Habib / Ammari, Habib