随机波浪边界层的数值模拟与分析

Numerical investigation of random wave boundary layer

该文基于雷诺平均的Navier-Stokes方程和k-ω两方程紊流模型建立了随机波浪边界层数学模型,模拟了粗糙底床上方的随机波浪边界层流速、床面剪切应力和紊动能量分布,计算结果与实测数据吻合良好。探讨了随机波浪边界层水动力特性,发现随机波浪时间序列中各个子波的紊动能量近似随该子波均方根自由振荡速度平方的增大而线性增大,但各个子波的紊动能量还受到上一个子波紊动能量传递的影响,体现了随机波浪与规则波浪的区别。整个随机波浪时间序列的有效摩阻系数和单个子波的摩阻系数均与前人实验数据和经验公式较为一致。

A numerical model for the random wave boundary layer is developed based on the Reynolds-averaged Navier- Stokes equations and the k- ω two-equation turbulence model. The model well reproduces the experimental measurement of flow velocity, bottom shear stress and turbulence quantities in the boundary layer under random waves. Numerical analysis reveals that the turbulence energy has a positive correlation to the root-mean-square free-stream velocity for individual waves. However, for each wave the turbulence energy is also affected by the past wave, indicating the history effects of random waves. Both the significant wave friction factor for the whole random wave series and the wave friction factors for individual waves agree with the existing experimental data and empirical formulas.