Acoustic propagation
in resonant media
The propagation of acoustic waves in scattering media is strongly affected by the mechanical resonances of the scatterers: dispersion, high attenuation, negative refractive index when several well-chosen resonances are excited, etc. A famous example is the Minnaert resonance of compressed bubbled which is exploited to attenuate sound. We are interested in scatterers exhibiting other mechanical resonances at low frequency – in translation and in rotation - for the purpose of affecting the propagation of both longitudinal and transverse waves in elastic media. The challenges are both to make these scattering materials, to characterize them and to model the propagation of coupled elastic waves.
Effect of translational resonances of dense and rigid spheres on longitudinal wave propagation - In collaboration with Mickael Duranteau, Tony Valier-Brasier and Jean-Marc Conoir (Institut d’Alembert), we demonstrated that the propagation of longitudinal waves in dispersions of dense and rigid spheres was strongly affected by their resonance in translation and showed that the model of Luppé, Conoir, Norris (2012) described quantitatively their propagation.
M. Duranteau, T. Valier-Brasier, J.-M. Conoir, R. Wunenburger, Random acoustic metamaterial with a subwavelength dipolar resonance, Journal of the Acoustical Society of America 39, 3341 (2016).
Effect of translational and rotational resonances of dense and rigid spheres on the propagation of transverse waves – In collaboration with Alverède Simon (PhD student) and Tony Valier- Brasier (Institut d'Alembert), using the ultrasonic rheology device, we evidenced the rotational resonance of dense and rigid spheres dispersed in an elastic medium. We showed that the propagation of transverse waves in these dispersions was strongly affected by both their translational and rotational resonances to the point of exhibiting a bimodal behavior at high concentration. We have shown that the model of Fikioris and Waterman (2013) quantitatively describes these phenomena.
A. Simon, R. Wunenburger, T. Valier-Brasier, Propagation of coherent shear waves in scattering elastic media, Physical Review E 103, L051001 (2021).
Currently, in collaboration with Quentin Baudis (PhD student) and Tony Valier-Brasier (Institut d'Alembert), we are studying the possible application of these diffusers to underwater stealth.