Computation of set-up, longshore currents, run-up and overtopping due to wind-generated waves
Computation of set-up, longshore currents, run-up and overtopping due to wind-generated waves
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发表时间：
1974-06
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通讯作者：
J. A. Battjes
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作者：
J. A. Battjes
本文研究的主要问题是随机波浪破碎对边坡的某些影响的计算。由于波浪破碎是一个高度非线性的过程，这个问题的解决非常复杂。由于气流夹带和湍流的产生，流场的均匀性比破碎带外的流场强得多，因此流场进一步复杂化。到目前为止，还没有对它进行现实的演绎处理。即使对于周期波的简单情况，关于破碎体某些宏观性质的经验知识仍然是有关冲浪带计算的一个组成部分。本文试图将这些知识应用到一个包含风浪随机性质的公式中。计算分为两类，一类是相对平缓的斜坡，另一类是相对陡峭的斜坡。结果的摘要将在下面给出。在第5章中，能量变化是通过剪切一个虚构的波高分布来计算的，理论上，如果没有发生破裂，它将存在于一个上限上，该上限是由一个适应的周期波的破裂准则确定的。计算结果与平面边坡的测量结果基本一致。对能量变化的了解允许对辐射应力进行评估，这对于计算装置和海岸洋流速度剖面是必要的。计算的装置轮廓与经验数据的比较没有得出决定性的结果。与实地数据很一致，但与实验室数据不一致，实验室数据显示，局部地区向海岸的上升幅度比根据测量或计算的波高变化所预期的要小。然而，对于用于测量实验室设置的系统，存在一些不确定性，因此不知道差异在多大程度上是真实的还是明显的。
The main problem dealt with in this thesis is the calculation of certain effects caused by random waves breaking on a slope. The solution to this problem is greatly complicated by the fact that wave breaking is a highly nonlinear process. The flow field is further complicated by far stronger in homogeneities than those occurring outside the breaker zone, by air entrainment and by generation of turbulence. No realistic deductive treatment of it has been developed so far. Even for the simpler case of periodic waves, empirical knowledge of certain macroscopic properties of the breakers is still an integral part of calculations relating to the surf zone. An attempt has been made in this thesis to apply this knowledge in a formulation incorporating the stochastic nature of wind-generated waves. The computations are of two distinct categories, those relating to comparatively gentle slopes and those relating to comparatively steep slopes. A summary of the results will be given in the following. The energy variation is calculated in chapter 5 by clipping a fictitious wave height distribution, which theoretically would be present if breaking did not occur, at an upper limit which is determined from an adapted breaking criterion for periodic waves. The computed results are in fair agreement with measurements carried out on a plane slope. Knowledge of the energy variation permits the radiation stresses to be evaluated, which in turn are necessary for the calculation of the set-up and the longshore current velocity profiles. A comparison of the calculated set-up profiles with empirical data has not given conclusive results. Good agreement has been found with field data, but not with laboratory data, which locally showed a systematically smaller rise towards the shore than would be expected on the basis of the measured or calculated wave height variations. However, there is some uncertainty with respect to the system used for measuring the set-up in the laboratory, so that is not known to which extent the differences are real or apparent.