给出了广义斯奈尔定律的相关理论推导,并总结回顾了之前的几种设计,包括声人工结构表面和几种声超表面的案例.首先,以人工结构表面为例,以解析推导为主,结合数值模拟和实验结果,证明了人工窄井结构的异常反射现象.随后,我们回顾了声超表面的设计方法,包括折叠空间式和亥姆赫兹腔式两种典型的结构化设计.最后,我们重点回顾了一种厚度仅为1/20波长的声超表面,用于设计超薄声扩散体,称为声超表面施罗德扩散体.传统的施罗德扩散体是40年前提出的建筑声学领域的经典设计,而我们提出的声超表面施罗德扩散体在中心频率具有同样优质的漫反射效果.另外,通过混合不同目标频率的超表面单元,可以设计宽带的超薄施罗德扩散体,其带宽接近于商业化的施罗德扩散体,这个例子充分展示了声超表面在实际场合的应用潜能.%In this paper, we investigate the theoretical derivations that related to the generalized Snell's law,and also review the previous designs,including artificial structure surface and several examples of acoustic metasurface. Firstly,we analytically,numerically and experimentally verify the abnormal reflection in"artificial grooves"structure. Then, we summarize the design methods of acoustic metasurfaces, including coiling-up-space structure and Helmholtz-resonator structure, respectively. At last, we review one special design of acoustic metasurface with the thickness of only 1/20 wavelength, and its use in design of ultra-thin acoustic diffuser,namely"acoustic metasurface Schroeder diffuser". Conventional Schroeder diffuser is a classical design proposed 40 years ago in architectural acoustics. Our designed acoustic metasurface Schroeder diffuser has comparable good diffusion effect at the center frequency. In addition, by mixing the unit cells designed for four different target frequencies, we can achieve broadband metasurface-based Schroeder diffuser, with the bandwidth comparable with commercial Schroeder diffuser, adequately showing the application potentials of acoustic meatsurfaces in practical occasions.
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