Ultrasonic wave transport in concentrated disordered resonant emulsions

TL;DR

This study investigates ultrasonic wave transport in concentrated resonant emulsions, revealing how near-field coupling influences scattering and transport properties, and identifying optimal droplet concentrations for non-diffusive wave behavior.

Contribution

It experimentally demonstrates the impact of resonant near-field coupling on wave transport in concentrated emulsions and identifies conditions for non-diffusive wave propagation.

Findings

Resonant emulsions show reduced scattering at high droplet concentrations.

An optimal volume fraction maximizes non-diffusive wave transport.

Maximum scattering occurs at an intermediate droplet concentration.

Abstract

We show how resonant (near-field) coupling affects wave transport in disordered media through ultrasonic experiments in concentrated suspensions. The samples consist of resonant emulsions in which oil droplets are suspended in a liquid gel. By varying the droplet concentration, the limits of the Independent Scattering Approximation are experimentally demonstrated. For the most concentrated samples, the proximity of resonant scatterers induces a renormalization of the surrounding medium, leading to a reducing of scattering strength. We point out an optimal volume fraction of oil droplets for which non-diffusive wave transport is experimentally demonstrated. Our demonstration of maximum scattering at an intermediate droplet concentration is very relevant for designing materials for the study of wave transport phenomena such as Anderson Localization.