The ultrasonic energy density in a close-packed disordered assemblage of glass beads immersed in water is shown to evolve in accordance with a diffusion equation. The diffusion and dissipation rates which parametrize the evolution equation are shown to be recoverable from the observed energy densities. The recovered diffusivity exhibits a frequency dependence which characterizes the microscale length and is in qualitative accord with theory. The recovered diffusivity also shows a slight dependence on source/receiver separation which is inconsistent with the hypothesized diffusion model; potential causes for this behavior are discussed. The recovered dissipation rate is greater than predicted by a model of viscous shear loss at solid/fluid interfaces. An estimate for the proximity of the Anderson transition is constructed.
ASJC Scopus subject areas
- Arts and Humanities (miscellaneous)
- Acoustics and Ultrasonics