On Near-cloak in Acoustic Scattering

TL;DR

This paper investigates acoustic near-cloaking using transformation optics, analyzing passive and active objects, and introduces a lossy layer to improve cloaking effectiveness with precise scattering estimates.

Contribution

It presents a novel approach to acoustic near-cloaking involving a lossy layer and provides detailed scattering amplitude estimates based on material parameters.

Findings

Near-cloak cannot be achieved without special mechanisms.

Incorporation of a lossy layer improves cloaking performance.

Derived accurate estimates of scattering amplitude.

Abstract

Invisibility cloaking in acoustic scattering via the approach of transformation optics is considered. The near-cloaks of both passive medium and active/radiating object are investigated. From a practical viewpoint, we are especially interested in the cloaking of an arbitrary (but regular) content. It is shown that one cannot achieve the near-cloak unless some special mechanism is introduced into the construction. A general lossy layer is incorporated into the construction of our near-cloaking devices. We derive very accurate estimates of the scattering amplitude in terms of the regularization parameter and the material parameters of the lossy layer in different settings.