Explanation and modelling of the mechanism of generation and development of breaking wave jet

(1)破碎波射流的产生条件和特征研究了均匀倾斜底礁孤立波破碎射流形成过程中水面剖面和速度场的变化。发现破碎波射流的大小取决于浅滩效应，并成为控制波浪运动水平不对称性的参数。2)倾覆射流下潜后的破波过程及其内部运动学。通过水力实验和数值模拟研究了由俯冲射流产生的大尺度相干涡流到小尺度湍流涡流的过渡过程。研究表明，相干涡流和夹带气泡的大小与射流尺寸参数呈线性关系，只有在射流破裂前用波浪模型对倾覆射流的大小进行评估，才有可能对破碎波过程进行理论分析。(3)俯冲射流对破波过程能量耗散和动量传递的影响，研究了礁石随机破波过程中动量传递引起的耗散和造波相关的透射系数。结果发现，透射系数和波浪设置是由每个波峰喷出的射流的运动学决定的，但可以用有效波高等统计数据来处理。4)浅水破浪射流的产生条件及特征。采用边界积分法进行数值模拟，明确了射流产生条件与入射波参数、底部地形和倾覆射流运动学的关系。5)倾落射流运动学与倾落后破碎波过程的关系。研究发现，倾覆射流的大小与水平速度之间存在独特的关系，约80%的倾降射流动量被吸收到射流的发展中。(6)射流落水后破碎波过程的建模与水力实验结果的对比验证了基于VOF方法和κ-ε模型的破碎波模型适用于射流落水后破碎波过程。少

1) Generation condition and characteristics of a breaking wave jetInvestigations were made on changes of water surface profiles and velocity fields in jet formation process of a solitary wave breaking on a uniformly sloping bottom and reef. It was found that the size of the breking wave jet depends on shoaling effect and becomes a paradmeter governing horizontal asymmetry of wave motion.2) Breaking wave processes after the plunging of a overturning jet and their internal kinematics.Hydraulic-experimental and numerical investigations were made on transient processes from large-scale coherent eddies generated by the plunging jet to small-scale turbulent eddies. It was made clear that the sizes of the coherent eddies and entrained air bubbles are in linear relations with the jet size parameter and a theoretical approach on the breaking wave processes becomes possible only if the size of an overturning jet can be evaluated by a wave model before breaking.3) Influences of the plunging jet o … More n energy dissipation and momentum transfer in wave breaking processesInvestigations were made on a transmission coefficient related to dissipation and wave set-up caused by momentum transfer in random wave breaking processes on reef. It was found that the transmission coefficient and wave set-up are governed by the kinematics of a jet ejected from each crest but can be treated by such statistics as significant wave height.4) Generation condition and characteristics of jet ejected from shallow water breaking wave.Relationships of jet generation condition to incident wave parameters, bottom topography and overturning jet kinematics were made clear through the numerical simulations using the Boundary Integral Method.5) Relationships between kinematics of plunging jet and breaking wave process after the plunging.It was found that there is a unique relation between the size and the horizontal velocity of overturning jet and about 80% of the momentum of the plunging jet is absorbed into the development of spray.6) Modelling of breaking wave process after the jet plungingIt was verified in comparison with hydraulic-experimental results that a model using the VOF method with the κ-ε model is applicable to the breaking wave process. Less