【作者】 吴伦宇；

【导师】 郭佩芳； 陈长胜； 侍茂崇；

【作者基本信息】 中国海洋大学 ， 物理海洋学， 2010， 博士

【摘要】 对近岸的一些基本海洋现象如潮汐、环流、风暴潮、海浪以及由此衍生的泥沙输运和海底地形变化的研究对海洋工程,环境保护等诸方面都有重要的意义。很多研究表明,这些现象不是孤立存在的,而是存在着较强的非线性作用,因此将它们作为一个整体来进行研究变得非常有必要。模型研究是当今物理海洋研究的一个非常重要的手段,目前耦合模型的情况是二维的多,三维的少；单向耦合的多,双向耦合的少；结构网格的多,无结构网格的少。由于近岸复杂的岸线和地形,选取一套能够很好的拟合岸线的非结构网格的模型来进行耦合研究就显得相当重要了。本文基于有限体积方法三角网格的水动力模型FVCOM、海浪模型FVCOM-SWAVE、泥沙模型FVCOM-SED,充分总结了当今先进的耦合技术,引进了三维辐射应力,与浪、流、泥沙皆有关的底边界模型,海表面应力模型,地形反馈等机制,建立了一套浪-流-泥沙耦合系统。首先总结了浪流耦合的研究历史和现状,包括理论研究和模型研究。然后通过两个理想实验对模型进行验证,包括个有角度海岸入射波和一个矩形海湾,第一个实验目的主要在于考察辐射应力对水动力模型的影响,第二个实验主要是考察相互作用模型,验证其中的主要耦合机制,并浅谈浪流泥沙共同作用下的海湾动力系统。在确保基本机制和程序编程无误之后,通过长江口杭州湾海域一次风暴潮过程,考察了浪、流、泥沙之间的相互作用并对模型的结果进行了解释,说明浪对流,流对浪,浪对泥沙悬浮以及浪沙对风暴潮水位的影响。由于风暴潮下的观察资料缺乏,继这次实验,结合渤海石油平台的风浪流同步观测资料,模拟了冬季一次大风过程,一是考察浪流之间的相互作用,二是通过实测资料来对模型进行检验。矩形海湾的试验中,得出主要结论是在地形变化显著的海区,考虑地形反馈以后流场有了显著的改变。在长江口-杭州湾的模拟中,指出在某些区域波浪对泥沙浓度影响比单纯考虑流高达一个量级,辐射应力对风暴潮水位起促进作用,浪流相互作用的底边界层的引入也起了促进作用,风暴潮计算应该同时考虑浪、流、泥沙之间的相互作用。在渤海的实验中,通过对BZ26平台的对比,水位模拟耦合以后与观测更接近,波浪由于该点流较弱,浪流相互作用不明显,但仍能看出模拟的波高随潮流的周期性变化。两个实际海区的实验都说明了潮位的变化只是在浅水区对波浪的影响较大,深水影响不大。流场对波浪模拟的影响在于多普勒效应以及流场时空的变化对绝对频率的影响,一般说来,波流同向的时候,波高受到抑制,波流反向的时候,波高增大。水深场的变化直接影响波参量如波速、摩擦力等的计算从而影响了波浪的传播与耗散。更多还原

【Abstract】 Study of the near-shore ocean phenomena such as tides, circulation, storm surges, waves, sediment transport and morphology has an important significance on marine engineering and environmental protection. Many studies have shown that these phenomena are not isolated while there are strong non-linear interactions between them, so studying them as a whole is quite necessary. Model has become an important tool to study physical oceanography. Most coupled models are two-dimensional or one-way or using structured grid. Due to the complex coastline and topography in near-shore, coupling between a set of unstructured grid models that can better resolve the coastline becomes important.Based on the finite volume method, triangular grid hydrodynamic model FVCOM, wave model FVCOM-SWAVE, sediment model FVCOM-SED, with the application of three-dimensional radiation stress, the waves-currents-sediment related bottom boundary model, sea surface stress model and morphology, a wave-current-sediment coupling system is set. First history and current study of wave current interaction are summarized, including the theoretical and model study. Then two ideal experiments are carried out to verify the model, including an incident wave with an angle on plane beach, and a tidal inlet. The first experiment is designed primarily to study the influence of radiation stress on the hydrodynamic model; the second experiment is to investigate the interactions in the coupled model, to verify the main coupling mechanism and discuss the wave-current-sediment inlet systems. After these two experiments, some basic coupling mechanisms and programming is fully tested. A storm surge case in the Yangtze River-Hangzhou Bay during is modeled to study wave, current, sediment interaction. As there were no observed data under storm surge for us to make the comparison, following this experiment, a simulation is made during a strong winter wind period in the Bohai Sea where there were observations on oil platforms. Thus we can test the model through observation.The inlet case mainly told us the flow field should be dramatically changed where there is a significant change in topography. In the Yangtze River-Hangzhou Bay simulation, we concluded that introducing waves can make sediment concentration one order larger in deeper water. Radiation stress can promote the water level in storm surge; the bottom boundary layer increased the water level also. In the Bohai Sea simulation, the water level are better after coupling; flows at the platform are quite weak and the interaction is small, but the modeled wave height varies with the tidal frequency due to the tides. Both the two applications show tide level change can influence wave only in shallow water. The current influence wave by Doppler shift and the its variability in time and space; generally speaking, wave height decreases when wave current are in the same direction and increases when their directions are opposite. The variation of water depth directly influences the calculation of wave speed and bottom friction which can change wave’s propogation and disspition.更多还原