Journal of Applied Mechanical Engineering

Super-radiating acoustic vortex beams with rotating porous media

3^rd International Conference on Fluid Dynamics & Aerodynamics

October 25-26, 2018 | Berlin, Germany

Cisco Gooding

University of British Columbia, Canada
University of Nottingham, UK

Posters & Accepted Abstracts: J Appl Mech Eng

Abstract:

The author will discuss the wave-structure coupling between an orbital angular momentum (OAM) beam and a rapidly rotating disk made of porous, sound-absorbing material. Motivated by exploring unknown features of how angular momenta affect wave-structure interactions, the author will present a new approach to the wave amplification effect known as rotational super-radiance. While rotational super-radiance was initially envisioned in terms of the scattering of an incident wave directed perpendicular to an object's rotation axis, the author demonstrate in the context of acoustomechanics that the same effect occurs for a vortex beam propagating parallel to the rotation axis. The author will argue that the experimental implementation of acoustomechanic super-radiance is feasible using current technology. There are two different experimental routes, one must either work with rotations high enough that the tangential velocity at the outer edge of the disk exceeds the speed of sound, or use evanescent (i.e. nonpropagating) sound waves. The author will then argue that the latter possibility is more promising, and provides the opportunity to probe a previously unexamined parameter regime in the acoustics of rotating porous media. An experimental implementation thereof will answer some of the open questions related to interactions of rapidly rotating wavestructure interactions.

Biography :

E-mail: cgooding@physics.ubc.ca