梁书秀，张怡辉，孙昭晨

(大连理工大学 海岸和近海工程国家重点实验室，辽宁 大连 116024)

深水波浪破碎时波浪演化特征实验研究

梁书秀，张怡辉，孙昭晨

(大连理工大学 海岸和近海工程国家重点实验室，辽宁 大连 116024)

采用能量聚焦的方式产生深水破碎波，并通过增加输入波陡使发生不同强度的波浪破碎现象。实验中，沿水槽中心位置布置22个浪高仪，分析波浪传播过程中的波面演化特征。对水槽不同位置处波面数据进行波能谱与小波能谱分析，发现在聚焦波传播过程中，低频能量部分保持相对稳定，而一次谐波高频部分先逐渐拓宽，经过破碎区域后又逐渐恢复。能量在高频部分有所损失，这种现象在破碎时更加明显，且破碎强度越大，越显著。波浪未破碎时，由于波浪传播过程中高频部分拓宽，导致聚焦前后特征频率略有增加，特征群速和特征周期略有减小；当波浪破碎时，由于破碎导致的能量损失比较明显，且卷破时更加明显，导致破碎后特征频率减小，特征群速和特征周期增大。

能量聚焦；波浪破碎；波能谱；特征波参数；聚焦波；波面演化

Abstract:In this paper,deep-water breaking waves are generated by the method of energy focusing in a wave flume and the intensity of wave breaking is toned by changing input wave steepness.In the experiment,the time series of surface elevation fluctuation along the flume is obtained utilizing 22 wave probes which are mounted along the mid-stream of the flume.The evolution characteristics of wave surface are analyzed.The spectrum is computed for surface elevations by a fast Fourier transform (FFT) and wavelet transformation.It is concluded that the energy keeps stable in low frequencies part and spreads toward the higher frequencies of the first harmonic band as the wave approaches the breaking zone.As the wave disperses again downstream,the spectrum returns to almost its initial shape,but the spectrum energy is lost in the high-frequency end of the first harmonic band,which is more appreciable when the wave breaking happens and is stronger.As the energy is spreaded to higher frequencies for non-breaking wave,the characteristic wave frequency becomes bigger and the characteristic group velocity and characteristic period become smaller after the wave focusing.When the wave breaking occurs,the loss in energy is obvious,leading to the characteristic wave frequency decreasing and the characteristic group velocity and characteristic period increasing after wave breaking,which is more appreciable for plunging wave.

Keywords:energy focusing; wave breaking; wave energy spectrum; characteristic wave parameters; focusing wave; wave surface evolution

波浪破碎是海洋中常见的现象，是许多海洋工程和海岸工程问题的重要影响因素。深水波浪(主要是风浪)发生破碎，会产生白浪，破碎波若遇到建筑物会产生很大的冲击力[1]。深水波浪破碎在海气作用中起着非常重要的作用，如能量从风向水体的转换、动量从波浪向水流的转移、湍混的生成以及湍-波的相互作用，是非常重要的流体动力学过程。……