Acoustic properties and dissipation in liquid foams, Camille Gaulon (University Paris Diderot) Jan. 25, 2017
DENORMS Action’s Workshop “Modelling of high performance acoustic structures Porous media, metamaterials and sonic crystals”, Rome, 24-25th January 2017
Session on Use of metamaterials in other fields of Physics and metamaterials exposed to multiple physical phenomena
Speaker: Camille Gaulon (University Paris Diderot)
Although metamaterials used as acoustic dampers are commonly open-cell porous materials, recent studies have shown the promising acoustic properties of liquid foams [1, 2]. The liquid foam skeleton is made of thin membranes (soap films) and liquid channels at the junction between the films, these structures enclosing gas bubbles. Liquid foams are thus constitutively closed-cell materials, but this is not a handicap for sound insulation. In fact, the strong coupling between the vibrations of the air, and the dynamics of the deformable films and liquid skeleton, leads to extraordinary phenomena. The effective density of the foam, which depends on the frequency and on the bubble's size, can for instance become negative . Liquid foams are thus natural and 3D acoustic metamaterials. Identifying the exact mechanism of the important acoustic attenuation is still a work in progress. In this presentation, I will show what are the main mechanisms underlying this acoustic dissipation in liquid foams.
 J. Pierre, R.-M. Guillermic, F. Elias, W. Drenckhan, V. Leroy, Acoustic characterisation of liquid foams with an impedance tube. Eur. Phys. J. E. 36, 113 (2013)
 J. Pierre, B. Dollet, V. Leroy, Resonant Acoustic Propagation and Negative Density in Liquid Foams. Phys. Rev. Lett. 112, 48307 (2014)
 S. Kosgodagan Acharige, F. Elias, C. Derec, Soap film vibration: origin of the dissipation. Soft Matter 10, 8341 (2014)