波作用量守恒原理在波流相互作用中的应用

APPLICATION OF CONSERVATION LAW OF WAVE ACTION FLUX TO WAVE CURRENT INTERACTION

波和流相遇后，经过相互作用产生稳定的波流场．基于波作用量守恒原理，本文提出了解决Ｓｔｏｋｅｓ波与指数剖面流同向或反向相遇过程中波传播特性改变问题的五阶理论，给出了这种相互作用前后波参数间的关系和相应流场的变化，并与线性结果进行了比较．结果表明，当波流同向时，波变平缓；当波流反向时，波明显变陡．随着波流强度的增加，非线性的影响变得越来越明显，尤其当波同反向流相遇时，波幅显著增大。

When surface ocean waves are intercepted by currents,the interaction between them takes place and finally a steady wave current coexisting flow is formed.Based on the principle of conservation of wave action flux,a fifth order theory to solve the problem of interaction between Stokes waves and exponential profile currents is proposed in this paper. The variation of wave parameters during the interaction process is at first studied, and the corresponding flow fields are obtained,then the results are compared with linear ones. It is shown that waves are steepened markedly when waves propagate against currents and flattened when waves travel with currents. As the wave amplitude and the current strength increase,the effects of nonlinearity become more prominent,and the errors caused by neglecting nonlinear effects grow up rapidly. If the adverse current is strong enough,the error is so large that the linear theory can not be applied any more.