潜堤后高阶自由谐波的研究
Study on the higher free harmonic waves on the lee side of a submerged bar
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摘要: 基于高阶边界元方法的完全非线性数值水槽模型模拟潜堤地形上波浪的传播变形,通过与实验值进行比较,考察数学模型的正确性。采用两点法分离得到堤后高倍频自由波来研究入射波参数、水深对堤后高倍频自由波的影响。研究发现:基频波、二阶和三阶自由波幅值分别与入射波波幅成线性、二次和三次函数关系,基频波幅值基本不随波浪周期变化,而二阶和三阶自由波幅值随波浪周期呈二次和三次函数关系增长。在保持入射波参数不变的情况下,堤后基频波的幅值随水深的增大在入射波幅值附近波动,没有明显的变化。Abstract: A three-dimensional fully nonlinear numerical wave tank (NWT) based on a time-domain higher-order boundary element method (HOBEM) is used. The numerical model is applied to simulating wave transformation over a submerged bar. The present model is validated by comparison with the experimental results. A two-point method is introduced to decompose higher harmonic waves on the lee side of the submerged bar. And then the evolutions of the wave amplitude of the nth free waves with incident wave characteristics and the water depth are further studied. It shows that the amplitude of fundamental waves varies linearly with the incident wave amplitudes. It also indicates that the amplitude of the second-order and third-order free waves can be represented by a quadratic and cubic function of the amplitude of incident waves, respectively. A conclusion can be obtained in which the amplitude of fundamental waves remains approximately unchanged with the incident wave periods. In contrast, the amplitude of the second-order and third-order free waves obeys a quadratic and cubic law with the incident wave periods, respectively.
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Key words:
- numerical wave tank /
- two-point method /
- higher harmonic free waves /
- submerged bar /
- fully nonlinear
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