This experiment demonstrates the generation of trapped acoustic surface waves excited by a turbulent flow source through the coupling of pressure fluctuations at the interface between an acoustic metamaterial and a flow environment. The turbulent flow, which behaves as a stochastic pressure source, was interfaced with an acoustic metasurface waveguide stationed in a quiescent environment via a single Kevlar-covered cavity, which ensured no significant disturbance to the flow. The metasurface waveguide produced an acoustic surface mode through evanescent diffractive coupling of the pressure field. This acoustic mode was trapped at the quiescent surface, with its mode dispersion determined by the surface geometry. The results of two different metasurface geometries are discussed: 1) a slotted cavity array, and 2) a meander connected cavity array, with each demonstrating a different trapped surface wave characteristic. Fourier transform and correlation analyses of spatially resolved temporal acoustic signals, measured close to the metamaterial surface, were used to construct the frequency- and wavevector-dependent acoustic mode dispersion. The results demonstrate that the flow can be used to excite acoustic surface modes and that their mode dispersion may be tailored toward realizing novel control of turbulent flow through acoustic-flow interactions.

该实验演示了通过声学超材料和流动环境之间界面处的压力波动耦合，由湍流源激发的捕获声表面波的产生。作为随机压力源的湍流通过单个 Kevlar 覆盖的腔与位于静止环境中的声学超表面波导接口，这确保对流动没有显着干扰。超表面波导通过压力场的渐逝衍射耦合产生声表面模式。这种声学模式被困在静止表面，其模式色散由表面几何形状决定。讨论了两种不同的超表面几何结构的结果：1) 开槽腔阵列，和 2) 弯曲连接的腔阵列，每个都展示了不同的捕获表面波特性。在超材料表面附近测量的空间分辨时间声信号的傅立叶变换和相关分析用于构建频率和波矢量相关的声模式色散。结果表明，流动可用于激发声表面模式，并且它们的模式分散可以调整为通过声流相互作用实现对湍流的新颖控制。