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: 0101572
• 负责人: Jerry Bona
• 金额: $ 86.57万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2002-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0101572&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.

这里提出的是一项研究，具有表面和内部海洋波与沉积物的底部地形的相互作用的模型。 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，将数值模拟的输出与现场数据进行比较，使用模型进行预测，并将其开发为有效的海岸工程工具。 所考虑的基本问题是具有挑战性的，因为它涉及到两个自由表面的动态连接在一个复杂的和非线性的方式的时间演变。 波浪运动涉及水面的变形，或者在内波的情况下，涉及密斜波。 即使在固定的底部，这些问题也很难精确表达，因此通常使用模型方程。 在目前的概念中，底部是不固定的，这种增加的复杂性使得这里提出的科学研究问题非常有趣。 在视图中是三维模型，从深水传入波场启动。 这些模型将考虑沿岸变化并考虑反射。 计划开发这种模型，并根据实验室实验和实地观察对其进行广泛测试。 在世界各地的几个地点，包括美国陆军工程兵团在北卡罗来纳州达克的实地研究设施，波兰科学院在波罗的海的一个地点，圣劳伦斯湾马格德兰群岛的北海岸，澳大利亚的黄金海岸，突尼斯海岸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）。 进行上述研究的动机有几个方面。 首先是学科的纯科学性。 该项目涉及流体力学、偏微分方程和泥沙输运理论等有趣而实质性的问题。 其次，它是一个理想的场所，让学生熟悉跨学科的研究。 这项研究也有很强的现实原因。 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，并进一步降低目前的，有时是灾难性的许多海滩的状态。 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的明显恶化迹象，并因社会发展压力而加剧。 严重的侵蚀很可能在半个世纪内蔓延到许多沿海地区，从而增加了对有效预防方法的需求。 本项目旨在加深我们对基本波浪-海底相互作用过程的理解，特别是关于沉积物扩散的理解。除了科学，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。 根据已有的经验，显然有各种保护方案，简单地建造一些永久性的、往往丑陋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。 当它们能够工作时，它们要便宜得多。 对保护计划的实用性的评估，无论是"硬"还是"软"，都取决于在本项目主持下调查的知识种类。