沙坝及人工沙坝引起海洋表面波Bragg共振反射的研究进展

Advances in Research on Bragg Resonance of Ocean Surface Waves by Sandbars and Artificial Sandbars

在海湾或开阔海岸的天然海滩上经常会发现平行于海岸且间距近似周期变化的沙纹和沙坝地形.当来自外海的表面波在一大片沙纹或沙坝上传播时,一旦满足Bragg(布拉格)条件,即表面波波长约为相邻沙纹沙坝间距的两倍时,则沙纹沙坝地形对入射表面波可形成Bragg共振反射,将其大部分能量反射回外海.受天然沙纹沙坝地形导致的Bragg共振反射现象的启发,科学家们提出建造由一组小型、高度不高、与岸平行且等间距的人工沙坝组成的Bragg潜堤用于抵御风暴波对海岸及近岸设施的冲击.自20世纪80年代初至今的三十多年来,天然沙纹沙坝和Bragg潜堤吸引了很多学者的关注,成为水波研究的一个热点.本文拟对三十多年来有关天然沙纹沙坝与海洋表面波相互作用的物理机制的理论研究和有关Bragg潜堤的应用研究给予一个简要的综述.

On natural beaches nearly periodic shore-parallel sand ripples and sandbars can be often found in bays or on open coasts. When surface waves coming from the ocean propagate o- ver patches of sand ripples and sandbars, once the Bragg condition is met, that is, the wave- length of surface waves is twice of the sandbar spacings, the Bragg resonant reflection may oc- cur to cause a large portion of the incident wave energy to be reflected back to the ocean. In- spired by the Bragg resonant reflection phenomenon of natural sand ripples and sandbars, some pioneering scientists proposed the so-called Bragg submerged breakwater consisting of a series of small-size, low-height, shore-parallel artificial bars placed just outside the surf zone to shel- ter the coast and near-shore facilities from the attack of storm waves. A brief summary of the advances in research on Bragg resonance between ocean surface waves and natural sandbars as well as Bragg submerged breakwaters since 1980s was presented.