Abstract
We theoretically and numerically propose an open bend tunnel with the capability of realizing ultra-broadband unidirectional transmission. The designed tunnel can isolate acoustic wave incidence from opposite directions and substance like the fluids or objects can exchange freely by employing acoustic gradient metasurface. The underlying mechanism is due to apparent negative reflection in ultra-broadband frequency range when the incoming angle impinging on the metasurface is over the critical incidence. The numerical results keep a good agreement with the theoretical analyses. The proposed design could be employed to generate various situations, like broadband noise control, architectural acoustics and ultrasound imaging.
Highlights
Researching acoustic diode (AD) technology has become an interesting and challenging problem in both scientific and engineering communities since sound has been thought to propagate along two opposite directions in any path
Recent studies report the result of surface negative refraction and negative reflection when the incoming angle impinging on the metasurface is over the critical incidence[27,29]
Gradient acoustic metasurface plays a crucial role in reflection wave-steering capability, which is employed against the conversion symmetry between incident waves and reflection waves on the surface
Summary
Researching acoustic diode (AD) technology has become an interesting and challenging problem in both scientific and engineering communities since sound has been thought to propagate along two opposite directions in any path. The influence of incident frequency on negative reflection is still absent so far when the incoming wave impinging on the metasurface over the critical angle.
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