不规则波辐射应力的精确解与近似解

Exact solution and approximate solution of irregular wave radiation stress

波浪辐射应力是波生沿岸流乃至近岸流的主要驱动力。波浪辐射应力的计算将直接关系到沿岸流的大小及其水动力特性。不规则波相对规则波更能反应实际海洋中的波浪运动,因此不规则波作用下辐射应力的计算将更能体现实际沿岸流中的波浪驱动力。通过推导给出不规则波辐射应力计算的精确解与近似解,并对两种计算方法进行了分析比较,在此基础上进一步用波生沿岸流试验结果对近似计算方法中的波能计算进行了验证。结果表明窄谱情况下,不规则波辐射应力的近似计算方法已有较好的精度,可节省大量的计算时间,从而提高计算效率,但精确计算方法更能准确反应各时刻各位置辐射应力的波动状况。

The wave radiation stress is the main driving force of wave induced longshore current and even nearshore current.It is directly related to the size and hydrodynamic characteristics of longshore current whether the calculation of the wave radiation stress is accurate or not.Irregular waves are more capable of reacting wave motion in the ocean compared to regular waves.Therefore,the calculation of the radiation stress under irregular waves will be more able to reflect the wave driving force in the actual longshore current.The exact solution and approximate solution of the irregular wave radiation stress are derived and compared with the two kinds of calculation methods.On the basis of this,the experimental results of wave-driven longshore currents are used to verify the calculation of wave energy in the approximate calculation method.The results show that:the approximate calculation method of irregular wave radiation stress has a good accuracy under the condition of narrow spectrum,which can save a lot of computing time and thus improve the efficiency of calculation.However,the exact calculation method can accurately reflect the fluctuation of radiation stress at each moment and each location.