Acoustic band gaps and localization in water with air-cylinders

Abstract

Multiple scattering of waves may lead to many peculiar phenomena such as complete band gaps in periodic structures and wave localization in disordered media. Within the gaps excitations are evanescent, when localized waves remain confined in space until dissipated. Here we show that waves are not always localized in 2-D, but when localized there is a coincidence between the gaps in periodic structures and the ranges of localized states in the case of acoustic propagation through water containing an array of air-cylinders. We report that inside the gap or localization regime, an interesting collective behavior of the cylinders appears. Exact numerical calculations reveal the unexpected result that localization is relatively independent of the precise location or organization of the scatterers.