Acoustic properties of emulsions with locally resonant scatterers
Résumé
We present the results of ultrasonic pulse propagation experiments on dilute emulsions of resonant scatterers. Thanks to microfluidics, we achieved highly monodisperse oil-droplet dispersions embedded in a Bingham fluid. Underwater measurements allowed us to evidence up to about ten sharp Mie resonances, on both the acoustic attenuation and the phase velocity in the MHz range. These ultrasonic experiments are compared to theoretical predictions derived within the framework of the independent scattering approximation with an excellent quantitative agreement. The influence of the emulsion polydispersity is also investigated as well as the dependence of the acoustic properties on both size droplet and volume fraction in dilute regimes, for which the coupling between scatterers is negligible.
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