Propagation of Ultrasound Waves in Concentrated Suspensions
Résumé
We have measured the phase velocity and attenuation of a coherent acoustical wave propagating in a macroscopic suspension. The frequency range corresponds to resonant scattering of particles (kd ∼ π, where k is the wave vector and d the diameter of particles), at high concentrations (5% to 30%). We have developed a spectral method to measure the velocity and the attenuation on a wide band of frequency, by means of signal processing using Fast Fourier Transform. The results are compared with an effective medium theory (Waterman and Truell). We obtain a good agreement, even for the resonant scattering frequency range.