摘要
Phillips谱是海浪实时绘制中常用的波浪谱。首先分析了Phillips谱的结构,指出该谱是一个瞬时空间谱,其频率谱符合Neumann形式,与P-M谱接近,其方向分布函数为国际拖曳水池会议推荐的形式。令P-M谱与Phillips谱具有相同的单位面积波能,给出了Phillips谱风速的确切含义并计算出该谱的常数。除了使用Phillips谱,还尝试其它形式的谱。用P-M谱和cos-2s形式方向分布函数构造了瞬时空间谱PM-cos2s形式,用JONSWAP谱和Poisson形式方向分布函数构造了瞬时空间谱J-Po形式。比较3种谱的绘制结果发现,使用Phillips谱、PM-cos2s谱的绘制结果均能反映风速对海浪的影响,不能反映风距的影响,使用J-Po谱的绘制结果既能反映风速、也能反映风距对海浪的影响,且三者的绘制帧率一致。如果要选择适合航海模拟器中海浪绘制的瞬时空间谱,该谱的风参数既应包括风速,也应包括风距,且生成波应在风向的(-?,?]范围内,因此J-Po谱在三者中最适合航海模拟器。绘制结果已应用于航海模拟器中。
The Phillips spectrum is widely used in ocean wave real-time rendering. First, the structure of the spectrum is analyzed. The Phillips spectrum is an instantaneous spatial spectrum. Its frequency spectrum is in accord with the spectrum form raised by Neumann and similar to the P-M spectrum. Its directional distribution function is that recommended by the international towing tank conference. On the hypothesis that the wave energy per unit area of the Phillips spectrum equals that of the P-M spectrum, the spectral constant is computed, and the spectral wind speed is clarified. In addition to the Phillips spectrum, other spectra are tried as well. The P-M spectrum and the directional distribution function of cos-2s form are used to construct an instantaneous spatial spectrum, denoted as PM-cos2s form, and the JONSWAP spectrum and the direction distribution function of Poisson form are applied for constructing an instantaneous spatial spectrum, denoted as J-Po from. The comparison of the rendering results of the three spectra shows that the wave rendered with the Phillips spectrum and PM-cos2s spectrum can reflect wind speed influence on the wave, but cannot embody the fetch length influence, while the wave rendered with J-Po spectrum can show the fetch length effect along with wind speed on the wave. With the same computer hardware, the frame rates of the three spectra are equal. For wave rendering in the nautical simulator, the wind parameter of the selected spectrum should contain the wind speed as well as fetch length, and the generated wave of the spectrum should distribute in(-?,?] of the wind speed. So J-Po spectrum is more suitable than the other two for the nautical simulator. The method was used in the nautical simulator.
出处
《图学学报》
CSCD
北大核心
2014年第2期173-180,共8页
Journal of Graphics
基金
国家973重点基础研究发展规划基金资助项目(2009CB320805)
中央高校基本科研业务费专项资金资助项目(2012TD002)
