Experimental Study on Wave Breaking in Relation to Coastal Processes

在波浪破碎的研究中采用了流场显示和图像分析的实验技术，并采用拉格朗日框架进行数值计算。利用高速录像机和模数转换器组成的测量系统，以分散的聚苯乙烯小球为示踪剂，可以精确地获得波浪破碎条件下的瞬时速度场。在设计速度和压力求解方法时，解决了拉格朗日描述数值分析中的技术难题，这些技术的应用为研究波浪破碎现象提供了新的途径，从而得出结论：波峰附近出现低压区是最直接、最明显的破碎指标。通过波浪水槽实验，对波浪在陡海滩上破碎及由此产生的旋涡进行了宏观研究。试验数据表明，深水波浪陡度和底坡对溢流型、倾翻型、溃缩型和纵荡型破波有明显的区分。在不同的底坡和雷诺数范围内，斜向涡和水平涡的出现频率不同

Experimental techniques of flow visualization and picture analysis have been applied to the investigation of wave breaking as well as the Lagrangian framework for numerical computation. Instantaneous velocity fields under wave wave breaking conditions could precisely be obtained by utilizing a measuring system of a high-speed VTR camera and an A-D converter with scattered polystyrene beads as tracers. Technical difficulties that accompany numerical analyses based on the Lagrangian description were coped with in devising both velocity and pressure solution methods.Application of these techniques permitted new approaches to wave breaking phenomena, leading to the conclusion that occurrence of low pressure region in the vicinity of a wave crest is the most direct and apparent breaking index. Increases in horizontal and vertical velocity components respectively cause such catastrophes in progressive and standing breakers.Another series of wave-tank experiments were conducted for macroscopic investigation of wave breaking on a steep beach and resultant vortices. The experimental data indicates that the demarcation of spilling, plunging, collapsing and surging breakers is clearly made in terms of the deepwater wave steepness and bottom slope. It was also found that oblique and horizontal voltices occur in different ranges of the bottom slope and Reynolds number defined by using the breaking wave height and celerity