Acoustic cloaking in a mean flow

Acoustic cloak is a metamaterial that makes the cloaked objects impervious towards sound waves. Existing acoustic cloak designs were originally formulated in a stationary medium. An acoustic shadow appears if those cloaking designs are located in a non- stationary flow field that discloses the concealed objects. A simple design is formulated to largely address this mean flow related issue, constituting the main contribution of the present article. The proposed new cloaking design is demonstrated in numerical simulations. The sound scattering from the cloaking design is studied using the model of linearized Euler equation. The background mean flow is calculated at low Mach numbers between 0 and 0.06, using potential and incompressible flow models, respectively. The performance of the proposed cloaking design is examined by studying both near- and far-field acoustic solutions.