CMG Collaborative Research: Simulation of Wave-Current Interaction Using Novel, Coupled Non-Phase and Phase Resolving Wave and Current Models

海浪带是近岸海域的一个空间有限但能量很高的区域，海浪在这里浅滩、破碎并向海岸线消散能量。在这里，非线性面波剖面强烈偏离了在更深的水域中假设的正弦的线性叠加，超谐锁相导致更尖锐、更高、更平的波峰和更平的波谷，而亚谐相互作用产生的低频运动可以主导内浪和激流(助跑)区的动力学。在飓风等严重风暴中，冲浪区变得特别重要，因为在飓风中，巨大的风浪可以与快速的洋流结合在一起，水位可能比正常水平高得多。飓风期间风浪-水流相互作用的后果可能会影响内陆风浪的传播，可能会影响远离内陆的洪水，并可能改变沉积物动力学，从而改变海岸的形状。不幸的是，由于需要非常高的网格分辨率、复杂的控制方程和令人望而却步的计算成本，对这一高度能量和重要区域进行准确和详细建模的能力一直受到限制。智力优势：该项目的长期目标是通过在当地纳入适当的物理和分辨率水平来提高飓风淹没、当前和波浪气候模型的精度。为了显著推进这一目标，将开发一个多过程、多尺度框架，将新的格林-纳格迪(GN)相分辨波(PRW)模式与现有的耦合波作用/长波环流模式相结合：这将极大地提高模拟强风暴和其他高能量事件期间详细近岸水动力学的能力。将在全球领域的不同部分应用和耦合不同的物理和分辨率水平。在不发生快速波变换的区域，将采用标准浅水方程和非相分解波能方程相结合的形式。新的GN水流和相分辨波动方程将模拟近岸和/或结构引起波浪破碎和爬升的狭窄区域的波浪和水流流体动力学。将研究与算法、耦合机制、物理和程序设计相关的大量研究问题。验证和确认工作将确认选定的物理和算法的充分性，而代码性能研究将证明这些技术的效率。该项目汇集了数学、计算科学、浅水流体力学、波浪物理、海岸工程和风暴潮建模方面的专业知识。广泛的影响：这项研究将提高对障碍岛、沙丘、近岸破碎区、内陆道路和堤坝等地物附近和后面的海浪、水位和水流的预测能力。这项工作的更广泛影响包括以下方面的改进：1)评估屏障或堤坝后面的洪水风险；2)评估沙丘、堰塞岛、堤坝、道路和铁路的实际退化；3)计算波浪破碎带后面的波浪抬高；4)确定堤坝、桥梁和建筑物等沿海建筑物周围的非线性波浪气候；和5)预测风暴潮和海浪，以帮助计划疏散，评估海岸风险，设计堤坝和关闭堤坝，并由联邦和州机构(包括联邦应急管理局、国家海洋和大气局、美国国家海洋和大气管理局和美国海军)运营航运。在该项目下开发的算法和计算基础设施可能适用于近岸海洋学和海岸工程的其他问题，包括水质、航运和港口作业、海军作业、海洋生态、天气和气候变化、湿地退化和重建。在更广泛的层面上，本项目将研究的计算技术适用于许多其他类型的可压缩和不可压缩流动问题。

The surf zone is a spatially limited but highly energetic region of the near-shore ocean where waves shoal, break and dissipate energy through to the shoreline. Here, nonlinear surface wave profiles deviate strongly from the linear superposition of sinusoids assumed in deeper waters, with super-harmonic phase-locking leading to sharper, higher, crests and flatter troughs, while subharmonic interactions generate low frequency motions that can dominate dynamics in the inner surf and swash (run-up) zones. The surf zone becomes especially important in severe storms such as hurricanes where large wind waves can combine with fast currents, and water levels may be much higher than normal. The consequences of the wind wave-current interaction during hurricanes can affect inland wind wave propagation, can influence flooding far inland, and can change the sediment dynamics and therefore the shape of the coast. Unfortunately, the ability to model accurately and in detail this highly energetic and important zone has been limited due to requirements for very high levels of mesh resolution, complex governing equations and prohibitive computational costs.Intellectual merit: The long-term objective of this project is to improve the accuracy of hurricane inundation, current and wave climate models by locally incorporating the appropriate physics and levels of resolution. To significantly advance this goal, a multi-process, multi-scale framework which integrates new Green-Naghdi (GN) phase resolving wave (PRW) models with existing coupled wave action/long wave circulation models will be developed: this will greatly improve the ability to simulate detailed near-shore hydrodynamics during severe storms and other highly energetic events. Different physics and levels of resolution will be applied and coupled in the various portions of the global domain. In regions where rapid wave transformation does not occur, the standard shallow water equation combined with a non-phase resolving wave energy equation formulation will be applied. The new GN combined current and phase resolving wave equations will model the wave and current hydrodynamics in narrow zones where near-shore and/or structure induced wave breaking and run-up occurs.Numerous research issues relating to the algorithms, coupling mechanisms, physics and code design will be investigated. Verification and validation exercises will confirm the adequacy of the selected physics and algorithms while code performance studies will demonstrate the efficiency of the techniques. The project brings together expertise in mathematics, computational science, shallow water hydrodynamics, wave physics, coastal engineering and storm surge modeling.Broader impacts: The study will improve the ability to predict waves, water levels, and currents near and behind features such as barrier islands, dunes, near-shore breaking zones, inland roads and levees. Broader impacts of this work include improvements in the ability to: 1) evaluate flood risk behind a barrier or levee; 2) assess the actual degradation of dunes, barrier islands, levees, roads and railroads; 3) compute wave run-up behind wave breaking zones; 4) determine nonlinear wave climate around coastal structures such as levees, bridges and buildings; and 5) forecast storm surge and waves so as to help plan evacuations, assess coastal risk, design levees and closures, and operate shipping by federal and state agencies including FEMA, NOAA, the USACE, and the U.S. Navy.The algorithms and computational infrastructure developed under this project may be applicable to other problems in near-shore oceanography and coastal engineering, including water quality, shipping and ports operations, naval operations, marine ecology, weather and climate change, and wetland degradation and rebuilding. On a broader level, the computational techniques to be studied under this project apply to many other types of compressible and incompressible flow problems.