FRG: Modeling Waves and Sediment Transport in Coastal Zones

FRG：模拟沿海地区的波浪和沉积物输送

• 批准号: 0234521
• 负责人: Jerry Bona
• 金额: $ 78.52万
• 依托单位: University of Illinois at Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-01-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0234521&HistoricalAwards=false
• 关键词: FRG; Modeling; Waves; Sediment; Transport

Proposed here is a study featuring models for the interaction of surface and internal oceanic waves with sediment-laden bottom topography. The project includes derivation and mathematical analysis of models, development of algorithms for the approximation of solutions, implementation of the algorithms as computer codes, comparisons of the output of numerical simulations with field data, the use of the models for prediction and their development as a tool for effective coastal engineering. The basic issue under consideration is challenging in that it involves the temporal evolution of two free surfaces whose dynamics are connected in a complex and nonlinear way. The wave motion involves the deformation of the water's surface, or in the case of internal waves, the pycnoclines. Even over a fixed bottom, these issues are difficult in their exact formulation, and consequently model equations are typically used. In the present conception, the bottom is not fixed, and this added complexity is what makes the issues proposed here for study scientifically very interesting. In view are three-dimensional models that are initiated by incoming wave fields from deep water. These models will allow for long-shore variation and take account of reflection. It is planned to develop such models and to test them extensively against both laboratory experiments and field observation. Comparisons are in view at several sites around the world, including the Field Research Facility of the US Army Corps of Engineers at Duck, NC, a site of the Polish Academy of Sciences on the Baltic Sea, the North Coast of the Magdelan Islands in the Gulf of St. Lawrence, the Gold Coast of Australia, the Island of Djerba off the Tunisian coast and two regions in Morocco (Alger in the Gibraltar Strait and Agadir on the Atlantic coast). The motivation for carrying out the study outlined above is several-fold. First is the pure science of the subject. The project involves interesting and substantial issues from hydrodynamics, partial differential equations, and sediment transport theory. Secondly, it is an ideal venue in which to acquaint students with interdisciplinary research. There is a strong practical reason for this study as well. The erosion and retreat of coastlines is a worldwide phenomenon. Global warming will increase the activity of storms, raise the sea level, and further degrade the present, sometimes catastrophic state of many beaches. Fragile Arctic coasts, beaches on the Great lakes and on many coastal regions already display the unmistakable signs of deterioration caused by these global changes and aggravated by social developmental pressure. Severe erosion is likely to spread to many coastal areas within half a century and thus increase the demand for effective prevention methods. The present project aims at deepening our understanding of fundamental wave-bottom interaction processes, especially as regards sediment dispersal. Going beyond the science, the project also grapples with the intelligent use of this kind of knowledge in designing coastal protection strategies. With experience already in hand, it is clear that there are a variety of protection options and that it is not always smart to simply build some permanent, often-ugly structure. So-called 'soft' protection methods are a useful addition to the reperatoire of the coastal engineer. These are much less expensive when they can be made to work. The assessment of the practicality of a protection plan, be it 'hard' or 'soft' relies upon the kind of knowledge investigated under the auspices of this project.

这里提出了一项研究，其特点是建立了表层和内部海洋波浪与富含沉积物的海底地形相互作用的模型。该项目包括模型的推导和数学分析，开发近似解的算法，将算法作为计算机代码执行，将数值模拟的结果与现场数据进行比较，将模型用于预测，并将其发展为有效的沿海工程工具。正在考虑的基本问题具有挑战性，因为它涉及两个自由表面的时间演变，这两个自由表面的动力学以复杂和非线性的方式联系在一起。波动涉及到水面的变形，或者在内波的情况下，是跃层的变形。即使在固定的底部，这些问题也很难准确地表达出来，因此通常使用模型方程。在目前的概念中，底部并不是固定的，这种增加的复杂性使这里提出的科学研究问题非常有趣。可以看到的是由来自深水的入射波场引发的三维模型。这些模型将考虑长岸变化并考虑反射。它计划开发这样的模型，并针对实验室实验和现场观察对它们进行广泛的测试。人们可以在世界各地的几个地点进行比较，包括位于北卡罗来纳州达克的美国陆军工程兵团的实地研究设施，波罗的海上的波兰科学院所在地，圣劳伦斯湾的马格德兰群岛北海岸，澳大利亚的黄金海岸，突尼斯海岸外的杰尔巴岛和摩洛哥的两个地区(直布罗陀海峡的阿尔及尔和大西洋海岸的阿加迪尔)。开展上述研究的动机是多方面的。首先是这门学科的纯科学。该项目涉及来自流体动力学、偏微分方程组和泥沙输运理论的有趣和实质性的问题。其次，这是一个让学生熟悉跨学科研究的理想场所。这项研究也有很强的实践理由。海岸线的侵蚀和后退是一个世界性的现象。全球变暖将增加风暴的活动，提高海平面，并进一步恶化许多海滩目前的、有时是灾难性的状态。脆弱的北极海岸、五大湖和许多沿海地区的海滩已经显示出这些全球变化造成并因社会发展压力而加剧的明显恶化迹象。严重的侵蚀很可能在半个世纪内蔓延到许多沿海地区，从而增加对有效预防方法的需求。本项目旨在加深我们对基本波底相互作用过程的了解，特别是关于泥沙扩散的过程。除了科学之外，该项目还努力在设计海岸保护战略时明智地使用这种知识。有了经验，很明显，有各种各样的保护选择，简单地建造一些永久性的、往往很难看的结构并不总是明智的。所谓的“软”保护方法是对海岸工程师技能的有益补充。当它们可以工作时，它们的成本要低得多。对保护计划的实用性的评估，无论是“硬的”还是“软的”，都取决于在该项目的主持下调查的知识种类。