Modeling on Transformation Process of Beach Profiles

这项工程的开展是为了获得描述波浪作用下海滩变形机理的基础知识。波浪破碎产生的大尺度涡流对波浪带泥沙运动起着重要作用。为了阐明这一机制，酒井用标记物和单元方法进行了数值分析，模拟了从俯冲式破碎器顶部撞击喷气式飞机后的剧烈运动。浅野用k-e模型计算了波浪作用下底部附近的湍流能量，并用随机方法研究了计算出的湍流能量下的含沙量。MASE提出了考虑均匀坡面上波浪破碎的随机波变换计算模型。该模型为随机波浪作用下的泥沙运动提供了有用的信息。平山发展了一种关于均匀坡度上的波的质量传输速度的新理论。这一结果是重要的，因为质量输运速度与泥沙运动密切相关。岩城总结了上述基本结果，并澄清了海滩剖面的变化可以用沉积物净速度的空间变化来解释。

This project has been carried out to obtain fundamental knowledge which describes the mechanism of beach transformation under wave action. Large scale vortices generated by wave breaking play an important role for the sediment movement in the surf zone. To clarify the mechanism, Sakai has performed a numerical analysis with a marker and cell method to simulate a violent motion after an impinging of a jet from a crest of a plunging breaker. Asano has calculated the turbulent energy close to a bottom under wave motion with a k-e model, and investigated the sediment concentration under the calculated turbulent energy by using a stochastic method. Mase has proposed a calculation model of random wave transformation including wave breaking on a uniform slope. The model gives useful information for the sediment movement under random waves. Hirayama has developed a new theory concerning the mass transport velocity due to waves on a uniform slope. The result is important because the mass transport velocity is closely related to the sediment movement. Iwagaki has summarized the above fundamental results and clarified that the transformation of a beach profile can be explained by the spatial variation of the net velocity of a sediment.