Study on Numerical Models of Nearshore Currents Including Wave Nonlinearity or Wave Irregularity

本文的研究结论如下：(1)从数学上证明了现有的椭圆波理论之间的相互联系，使得Capppelear理论包含了其他理论。(2)利用Stokes和椭圆波的高阶解分析了由于流深变化引起的波浪浅化和折射。(3)建立了用Stokes和椭圆波理论估计波浪特征的两个波浪变换和近岸流模型。(4)基于非线性长波方程的特征线解，建立了一维和二维波浪变换模型。这些模型同样适用于不规则波的变形计算。(5)建立了基于波作用谱密度守恒的不规则波在水流和水深作用下的折射计算模型。数值计算表明，海流的时间依赖性会导致对流作用下方向谱的放大效应减小。(6)建立了近岸结构不规则波诱导的近岸流模型，并对绕射和反射的影响进行了近似计算。该模型合理地解释了波变换的实验数据和与其结构构型相适应的电流模式的形成。

The conclusions of this study are as follows ;(1) Mathematical proof is given that the interrelation among the existing cnoidal wave theories is such that the Chapppelear theory includes the other theories.(2) Wave shoaling and refraction due to current-depth variations are analyzed with use of higher order solutions of Stokes and cnoidal waves.(3) Two models of wave transformation and nearshore currents in which wave characteristics are estimated with Stokes or cnoidal wave theory are established.(4) One-dimensional and two-dimensional models of wave transformation are developed on the basis of characteristics solution for nonlinear long wave equations. These models are also applicable to the computation of transformation of irregular waves.(5) A model for refraction computation of irregular waves due to time-varying currents and water depth is established on the basis of conservation of wave action spectral density. Numerical computation shows that time-dependency of currents gives rise to reduction in the amplification effect of directional spectrum due to opposing currents.(6) A model of nearshore currents induced by irregular waves in the presence of coastal structures is completed, in which the effect of diffraction and reflection are evaluated with approximate ways. The model reasonably explains the experimental data of wave transformation and the formation of curent patterns appropriate to their configuration of structures.