One-Way Acoustic Guiding under transverse mean flow

TL;DR

This paper demonstrates that transverse mean flow combined with structural asymmetry can induce strong nonreciprocity and one-way acoustic waveguiding, challenging the common belief that transverse flow does not break reciprocity.

Contribution

It reveals that transverse flow and structural asymmetry together can produce nonreciprocal and one-way acoustic guiding, a novel phenomenon in acoustics.

Findings

Transverse flow can cause nonreciprocity when combined with structural asymmetry.

One-way waveguiding is achievable under transverse mean flow.

Contradicts the traditional view that transverse flow does not break reciprocity.

Abstract

In a moving acoustic medium, sound waves travel differently with and against the fluid flow. This well-established acoustic effect is backed by the intuition that the fluid velocity bias imparts momentum on the propagating acoustic waves, thus violating reciprocity. Based on this conception, fluid flow that is transverse to the wave direction of propagation will not break reciprocity. In this letter we contrast this common wisdom and theoretically show that the interplay between transverse mean flow and transverse structural gliding-asymmetry can yield strong nonreciprocity and even, surprisingly, one-way waveguiding which is rare in acoustics.