透水珊瑚岸礁亚重力波水动力特性数值研究

Numerical study on infragravity wave hydrodynamics of permeable fringing reef

基于非静压单相流模型(NHWAVE),对随机波浪在透水珊瑚岸礁上传播过程进行了数值模拟,综合考虑入射波高、礁坪水深、谱峰周期、透水层厚度、透水层孔隙率以及颗粒的中值粒径等因素对岸礁波浪水动力特性的影响,重点分析了短波波高、低频长波波高、平均水位的沿礁变化,并与无透水层的岸礁情况进行了对比。研究表明:透水层的存在减弱了波浪在礁前斜坡的浅水变形和在礁缘附近的波浪破碎,显著降低了岸线附近的短波波高、低频长波波高以及波浪增水值,除此之外,透水层的存在会降低波浪在岸滩的最大爬高;透水层的孔隙率和颗粒的中值粒径对波浪传播变形特征的影响可忽略不计;入射波高和谱峰周期越大,岸礁透水层对短波、长波及波浪增水的影响越显著;当增大礁坪水深时,透水层对波浪的消减作用减弱;随着透水层厚度的增大,岸线附近的短波波高、长波波高和波浪增水值随之减小。

Based on the nonhydrostatic single-phase flow numerical wave model(NHWAVE),the propagation of random waves on a permeable fringing reef is simulated numerically,and the effects of incident wave height,water depth on reef flat,spectrum peak period,thickness of permeable layer,porosity and median diameters the hydro-dynamic characteristics of waves on the fringing reef are considered comprehensively,focusing on the variation of sea-swell wave height,infragravity wave height and mean water level along the reef,and comparing with that of the fringing reef without permeable layer.The study shows that the existence of the permeable layer has a significant impact on the hydrodynamic characteristics of waves on the fringing reef.The study shows that the existence of the permeable layer reduces the shallow water deformation of waves on the slope in front of the reef and the wave breaking near the reef edge,and significantly decreases the sea-swell wave height,infragravity wave height,and wave setup near the shoreline,in addition to that,the existence of the permeable layer reduces the maximum wave runup on the shoreline.The greater the incident wave height and spectrum peak period,the more significant the ef-fect of the permeable layer on the sea-swell wave,infragravity wave and wave setup on the fringing reef;when the water depth of the reef is increased,the effect of the permeable layer on wave attenuation is weakened;as the thick-ness of the permeable layer increases,the values of sea-swell wave height,infragravity wave height and wave setup near the shoreline decrease.