Experimental Study on Wave Breaking in Relation to Coastal Processes

流动可视化和图像分析的实验技术已被应用于波浪破碎的研究以及数值计算的拉格朗日框架。利用高速VTR相机和散在聚苯乙烯微珠作示踪剂的a - d转换器组成的测量系统，可以精确地获得波浪破波条件下的瞬时速度场。在设计速度和压力求解方法时，克服了基于拉格朗日描述的数值分析所伴随的技术困难。这些技术的应用为破波现象提供了新的途径，从而得出在波峰附近出现低压区是最直接和最明显的破波指标的结论。水平和垂直速度分量的增加分别在前进式和静止式破碎机中引起这种灾难。另进行了一系列波浪槽试验，对陡坡滩上的破浪及其产生的涡进行了宏观研究。实验数据表明，从深水波浪陡度和底坡度上可以清楚地划分出溢出型、倾入型、塌缩型和涌浪型。在用破浪高和破浪速度定义的底坡和雷诺数范围内，斜伏和水平伏发生在不同的范围内

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