双峰谱波浪诱发细长港低频振荡的物理试验研究

Experimental study of low-frequency oscillations in a narrow-long harbor induced by bimodal spectrum waves

针对低频波浪诱发港池振荡问题,通过物理模型试验研究了双峰谱中低频谱峰(fp1)和低频谱有效波高(Hs1)的变化对诱发细长港池低频振荡的影响。结果表明:1) fp1越接近港池第1共振频率,港内低频波浪响应越剧烈,通过fp1放大因子曲线可以准确识别港池的第1共振频率;同时Hs1的变化主要影响第1共振模态的波浪响应。2)基于平方小波二阶相关谱对港内波浪的非线性分析发现,fp1越接近港池第1共振频率或Hs1逐渐增大,港内波浪非线性相互作用均会明显增强。该研究结果对于涌浪和风浪长期共存的海域港口建设起到良好的指导作用。

In this investigation,aiming at the problem of low-frequency wave inducing harbor oscillations,the effects of the variation of the spectral peak frequency( fp1) and significant wave height( Hs1) of low-frequency spectral on the resonance within the harbor are systematically investigated by a physical model experiment. The experimental results show that: 1) The closer fp1 is to the first resonance frequency of the harbor,the stronger the low-frequency wave response is. The first resonance frequency of the harbor can be accurately identified by fp1 amplification factor curve. Simultaneously, the variation of Hs1 mainly affects the wave response of the first resonance mode. 2) Based on the squared-wavelet-based bicoherence spectra,it is found that the closer fp1 is to the first resonance frequency of the harbor or the larger Hs1 is,the stronger the nonlinear wave interaction is. The study results will play a good role in guiding the construction of the sea harbor where the swell and wind waves coexist for a long time.