潜堤上规则波辐射应力的数值研究

Numerical Study of Radiation Stress on the Submerged Bars by Regular Wave

在近岸波浪相关研究中,辐射应力是波动在水体中引起的剩余动量流,是波浪运动的重要物理量。在波浪从深水逐渐传向浅水的过程中,波浪的非线性逐渐增强,甚至会发生破碎等剧烈变形,引起辐射应力的强烈变化,对次重力波生成等有重要贡献。应用OpenFOAM精细模拟波浪在潜堤上的传播,得出波浪运动的详细流场信息,计算了有波浪破碎情况下潜堤地形上波浪的辐射应力和波浪增减水情况。研究结果表明,在潜堤地形下,辐射应力值在堤前平底处受波幅变化影响较敏感,波浪完全破碎后其值在堤后坡面处呈增大趋势直至平底处趋于平稳。辐射应力沿程变化对波浪增减水的影响趋势与波浪增减水方程符合良好。

In the study of nearshore wave,the radiation stress is an important physical quantity which is an excess momentum flow caused by waves.As waves transfer from deep water to shallow water,the nonlinearity of wave increases gradually and waves are deformed or even broken.This will cause strong shift in radiation stress and make significant contributions to the generation of infragravity wave.In this paper,OpenFOAM is used to fine simulate the propagation of waves on the submerged bars.In the case of breaking waves,the detailed flow field information of wave motion is obtained.Besides,the radiation stress and the wave set-up and set-down on the submerged bars terrain are calculated.Numerical results show that the radiation stress value is quite sensitive to the wave amplitude shift at the flat bottom before the submerged bars.When the wave is completely broken,the value of radiation stress increases at the back submerged-bars slope and then it tends to level off at the flat bottom behind the submerged bars.The effect of variation trend of radiation stress along the way on the wave set-up and set-down is in good agreement with the wave set-up and set-down equation.