Tunable acoustic superscatterer composed of magnetorheological fluid and maze-like metasurface

Abstract

Metamaterials have been widely studied in recent years, setting out their various exotic properties, but typically passive configurations are discussed, with limitations in frequency or loading performance. Here, we present a novel tunable acoustic superscatterer, a type of metamaterial, whose scattering cross-section in water can be varied with externally applied stimuli. The core of the superscatterer is filled with a magnetorheological fluid and the envelope is made of an extremely anisotropic acoustic metasurface in the form of a maze-like annular sleeve which can be additively manufactured. When an external magnetic field is applied in a direction perpendicular to the direction of the incoming acoustic field, the scattering boundary of the core is modulated, resulting in switchable total scattering cross-section of the superscatterer. Here we report analytical studies demonstrating this concept, as well as numerical simulation results that support the analytical results.