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

冲浪带是一个空间有限但能量很高的近岸海洋区域，波浪在这里聚集、破碎并将能量耗散到海岸线。在这里，非线性表面波剖面强烈偏离较深水域中假设的正弦波的线性叠加，超谐波锁相导致更尖锐、更高、波峰和更平坦的波谷，而次谐波相互作用产生低频运动，可以主导内部冲浪和冲刷（上升）区域的动力学。在飓风等猛烈的风暴中，冲浪区变得尤为重要，在这些风暴中，巨大的海浪可能与快速的水流结合在一起，水位可能远高于正常水平。飓风期间的风波-流相互作用的后果可以影响内陆风波的传播，可以影响内陆的洪水，可以改变沉积物的动力学，从而改变海岸的形状。不幸的是，由于对非常高的网格分辨率、复杂的控制方程和高昂的计算成本的要求，精确和详细地建模这个高能量和重要区域的能力受到了限制。智力价值：该项目的长期目标是通过在当地结合适当的物理和分辨率水平来提高飓风淹没、洋流和波浪气候模型的准确性。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Green-Naghdi （GN）相分辨波（PRW）模型与现有的波浪作用/长波环流耦合模型相结合：这将大大提高在强风暴和其他高能量事件期间模拟详细近岸流体动力学的能力。不同的物理和分辨率水平将被应用和耦合在全球域的各个部分。在不发生快速波变换的地区，将采用标准浅水方程结合非相分辨波能方程公式。新的GN结合了电流和相位分解波浪方程，将模拟近岸和/或结构引起的波浪破碎和上升发生的狭窄区域的波浪和电流流体动力学。许多与算法、耦合机制、物理和代码设计相关的研究问题将被调查。验证和确认练习将确认所选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、浅水流体动力学、波浪物理、海岸工程和风暴潮建模方面的专业知识。更广泛的影响：这项研究将提高预测堰洲岛、沙丘、近岸破碎带、内陆道路和堤坝等特征附近和后面的波浪、水位和水流的能力。这项工作的更广泛影响包括提高以下能力：1)评估屏障或堤坝后面的洪水风险；2)评估沙丘、堰洲岛、堤防、公路和铁路的实际退化情况；3)计算破波带后的波浪爬高；4)确定堤防、桥梁和建筑物等海岸结构周围的非线性波浪气候；5)预测风暴潮和海浪，以帮助规划疏散，评估沿海风险，设计堤坝和关闭，并为联邦和州机构（包括FEMA， NOAA， USACE和美国海军）运营航运。本项目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中的其他问题，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.