海堤越浪的数值模拟

基于RANS方程和两方程湍流模型，采用有限体积法，将人射波波场作为人工的分布源项加人动量方程，提出了适用于VOF方法的源造波一消波技术。通过对行波及驻波的计算，分别考察了数值波浪水槽前端及末端消波段的有效性。在本文建立的数值波浪水槽内对规则波在海堤上爬高和越浪过程进行了数值模拟，并将计算结果与现有实验结果进行了比较。验证计算结果表明，数值模拟结果较好地复演了海堤越浪过程。为了研究模型尺度对越浪量的影响，文中设计了一组满足重力相似但具有不同几何比尺的数值实验模型。系列数值实验结果表明，若按重力相似换算越浪量，计算结果与实验预报值间的偏差随模型比尺的增大和堤前波浪破碎强度的增强而增大，建议在进行越浪物理模型实验时需进一步考虑模型比尺对原型预报值的影响。

Numerical Simulation of Wave Overtopping over Seawalls

Based on the RANS equation and k-epsilon model, a numerical wave tank was presented in the frame of FLUENT through modifying the source terms of momentum equations by distributed sources associated with the incoming waves. Numerical simulation of progressive waves and standing waves was carried out to check if the numerical wave generation and absorbing module work well. It truns out that the numerical wave tank can be used to study the interaction of regular waves and structures in two dimensional cases. Wave runup and overtopping over a seawall were reproduced by using the numerical wave tank and compared with the experimental data available. Good agreements were obtained between the numerical results and experimental data. In order to study the scale effects of physical model experiments of overtopping, several numerical models of different values of geometry scale were designed which satisfy Froude similitude. Using the numerical models of different scales, the numerical experimental results show that, if based on Froude similitude, the differences of the computed values of overtopping flux and the predicted values from experimental data increases as the geometry scale increases and the wave breaking in the front of seawalls becomes stronger. It is suggested that the scale effect should be considered carefully when wave overtopping over a seawall is studied in a wave flume.