中文摘要：

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。

英文摘要：

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.