Nonlocal description of sound propagation through an array of Helmholtz resonators

Abstract

A generalized macroscopic nonlocal theory of sound propagation in rigid-framed porous media saturated with a viscothermal fluid has been recently proposed, which takes into account both temporal and spatial dispersion. Here, we consider applying this theory, which enables the description of resonance effects, to the case of sound propagation through an array of Helmholtz resonators whose unusual metamaterial properties, such as negative bulk moduli, have been experimentally demonstrated. Three different calculations are performed, validating the results of the nonlocal theory, related to the frequency-dependent Bloch wavenumber and bulk modulus of the first normal mode, for 1D propagation in 2D or 3D periodic structures.