Tunable enhancement of the acoustic radiation pressure acting on a rigid wall via attaching a metamaterial slab

We demonstrate that the acoustic radiation pressure acting on a rigid wall can be remarkably enhanced by introducing a supplementary metamaterial slab. The dramatic effect stems from the resonant excitation of the acoustic field sandwiched between the rigid wall and the metamaterial slab. Simple formulae for both the enhancement factor and the resonant wavelength are derived analytically, which coincide well with numerical results and exhibit excellent tunability via flexibly tailoring the metamaterials. The acoustic radiation pressure with such tunable magnification could be potentially useful, such as in designing ultrasound instruments and sensors.