为研究某岛礁周边波浪演化过程及其特征,本文选取西太平洋的-个典型岛焦地形为研究对象,在试验水池中建立了礁地形三维模型(1:100).造波机输入谱为Goda改进的J0NSWANP谱,谱峰升高因子γ取2.0,对不同有效波高和有效周期的定向随机波工况进行了试验.在岛礁周围布置多个浪高仪测定波浪的时间序列,并基于小波变换分析波面序列的小波谱特征.通过分析试验中的波浪演化过程,发现多个工况在地形突变处存在畸形波.通过分析小波能谱发现在畸形波近后方出现波群时,该波群会获得畸形波的能量,导致该波群的波能增大,并生成二次畸形波.试验发现地形突变会增大畸形波发生的概率.畸形波的形成与波浪的群性有关,且单次畸形波与二次畸形波演变特点存在差异.
To study the evolution process and the characteristics of waves around some reefs,the terrain of a typical reef in the western Pacific was chosen as the research object in this paper. The three-dimensional model on the reef terrain ( 1 :100) was set up in the test tank. The Goda-improved JONSWAP spectrum was applied as the input of a wave maker,with the spectral peak elevation factor γ equal to 2. 0. The behaviors of the directed random wave with various significant periods and wave heights were tested. Many wave gauges were laid out around the reef. In addi-tion ,the characteristics of the wavelet spectrum of the wave surface sequences were analyzed on the basis of the wavelet transform. By analyzing the evolution process of waves in the test,it was found that freak waves exist at the terrain break under many behaviors. By analysis of the wavelet energy spectrum,when a wave group appears near the back of freak waves,the wave group gets the energy of the freak wave,and the energy of the wave group increa-ses ;in addition,secondary freak waves could form. Also,the terrain mutation could result in a high probability of freak waves. The generation of freak waves has a certain relationship with the features of the wave group; in addi-tion, the evolution characteristics of single freak waves and secondary freak waves are different.