Achieving acoustic cloak by using compressible background flow

TL;DR

This paper introduces a novel acoustic cloaking method using background flow in compressible fluids, creating a virtual curved spacetime to guide sound waves around objects, with analytical solutions and effectiveness analysis.

Contribution

It presents a new acoustic cloaking scheme based on background flow in compressible fluids, including analytical solutions and practical considerations for real fluid conditions.

Findings

Sound waves can be guided around objects using background flow.

Analytical solutions for sound fields are derived for plane wave incidence.

Cloaking effectiveness is evaluated through scattering cross section analysis.

Abstract

We propose a scheme of acoustic spherical cloaking by means of background irrotational flow in compressible fluid. The background flow forms a virtual curved spacetime and guides the sound waves bypass the cloaked objects. To satisfy the laws of real fluid, we show that spatially distributed mass source and momentum source are necessary to supply. The propagation of sound waves in this system is studied via both geometric acoustics approximation and full wave approach. The analytic solution of sound fields is obtained for plane wave incidence. The results reveal the effect of phase retardation (or lead) in comparison with the ordinary transformation-acoustic cloak. In addition, the ability of cloaking is also evaluated for unideal background flows by analyzing the scattering cross section.