Scattering pattern of acoustic metamaterial in steady flow around an object

Abstract

In this paper, we propose a new method to study acoustic metamaterial in flow field. Research on an effect of an aerodynamic flow on sound propagation is critical to metamaterial applications in physical situations. Previous investigations have clear limitations with assumptions of incompressible steady flow and impractical anisotropic material properties in cloaking metamaterials. Thus, we propose a new theoretical framework for a physical analysis for an effect of compressible flow on acoustic cloaking metamaterials. By formulating a convective wave equation for an inviscid, compressible and steady flow, the differential operator on the left hand side of the equation contains a non-uniform velocity vector. By illustrating numerical simulations using the proposed framework, we analyse the physical phenomena in detail. The new framework could help to understand the physical background of acoustic metamaterials in flow field, and thus, we can conceptually realize the new aeroacoustic metamaterials.