Approximate Acoustic Cloaking in Inhomogeneous Isotropic Space

TL;DR

This paper demonstrates how transformation media and sound-soft layers can achieve near-invisibility in inhomogeneous isotropic space through approximate acoustic cloaking, using novel scattering estimates for small obstacles.

Contribution

It introduces new scattering estimates that handle mixed obstacle sizes without scaling arguments, advancing acoustic cloaking in complex media.

Findings

Achieved near-invisibility using transformation media and sound-soft layers.

Developed novel scattering estimates for small and regular obstacles.

Decoupled nonlinear scattering interactions in inhomogeneous media.

Abstract

In this paper, we consider the approximate acoustic cloaking in inhomogeneous isotropic background space. By employing transformation media, together with the use of a sound-soft layer lining right outside the cloaked region, we show that one can achieve the near-invisibility by the `blow-up-a-small-region' construction. This is based on novel scattering estimates corresponding to small sound-soft obstacles located in isotropic space. One of the major novelties of our scattering estimates is that one cannot make use of the scaling argument in the setting of current study due to the simultaneous presence of asymptotically small obstacle components and regularly sized obstacle components, and one has to decouple the nonlinear scattering interaction between the small obstacle components and, the regular obstacle components together with the background medium.