Possible localization of sound propagation in hard-sphere gases

Abstract

The effects of disorder (or free-orientation) using the discrete velocity model for the possible (dynamical) localization of (plane) sound waves propagating in dilute monatomic hard-sphere gases are presented. Comparison with previous fixed-orientation (θ = 0) results show that there exists a certain gap in the spectra when the disorder or free-orientation exists and when a periodic medium with a gap (in spectra) is (slightly) randomized (like our orientation-free 4-velocity case) possible localization occurs in the vicinity of the edges of the gap.