高阶谱方法建立三维畸形波聚焦模拟模型

Focusing model for generating 3-D freak waves based on HOS method

三维波浪方向聚焦是畸形波形成机理之一。为了模拟和分析这一现象,在势流理论内基于改进的高阶谱(HOS)方法,给出了时空聚焦方式生成畸形波的三维波浪模型。利用满足周期性边界条件的具有不同频率、不同传播方向的各独立组成波,分隔了计算域内的能量;使各组成波采用等振幅能量分布的形式,聚焦模拟了实验尺度畸形波;把高阶谱方法拓展到大尺度的开敞海域,考虑波浪方向分布的影响,聚焦模拟了大尺度畸形波的发展和形成过程。

Three-dimensional directional wave focusing is one of the mechanisms that contribute to the generation of freak waves. To simulate and analyze this phenomenon, a three dimensional wave focusing model is studied within the framework of potential flow theory. The model for simulating fully nonlinear water waves is presented based on enhanced high-order spectral （HOS） numerical method. Total energy is divided by wave components having different directionali .ty and wave frequencies in periodic domain. Small-scale freak wave events are obtained with wave components having equal amplitudes, and resnlts are then discussed. Investigations of freak-wave events appearing in open seas defined by a directional wave spectrum are then realized.