Phenomenological law for the acoustic reflection by an array of cylindrical cavities in a soft elastic medium

Abstract

We propose a phenomenological model, built from results obtained by finite-element numerical simulations, for the transmission and reflection of acoustic waves by a two-dimensional array of cylindrical cavities in a soft elastic medium. We show that the acoustic properties of a cylindrical cavity can be described by two geometrical parameters: its aspect ratio (AR) and the radius of the sphere of equivalent volume. Cylinders with AR close to one are acoustically similar to spheres, whereas flat cylinders exhibit a lower resonance frequency and an increased damping due to their ability to emit shear waves. We provide an example of how our new phenomenological analytical model can help to design thin coatings that can turn strong acoustic reflectors into good absorbers.