On the acoustic invisibility

Abstract

Over the past decade a great attention has been paid to the modeling and simulation of making objects invisible or deaf to noise. The recent results have enlightened the mode of control and handling the invisibility and cloaking to noise using the metamaterials engineered at the subwavelength scale in order to interact with acoustic field in a way that traditional materials do not. The acoustic invisibility is based on the property of acoustic equations to be invariant under a spatial compression that means a manipulation of the material parameters. In this paper, the sound invisibility performance is discussed for spherical cloaks. The original domain consists of an alternation of layers made from piezoelectric ceramics and epoxy resin, following a triadic Cantor sequence. The spatial compression, obtained by applying the concave-down transformation, leads to a metamaterial layer with an inhomogeneous and anisotropic distribution of the parameters.