ITR/AP(DMS): Numerical Studies of the Nonlinear Interaction Between Turbulent Air Flow and Sea Surface Waves, with Application to Ocean Surface Wave Turbulence

这项拟议的项目开发了一个非线性演变水面上湍流气流的数值模型，克服了以前研究的局限性。用于模拟气流的高效计算算法、用于演变海面边界的高效流体动力学方法以及并行计算技术将结合在一起，使二维和三维现实问题的统计分析成为可能。将使用科学可视化方法来分析结果，并提高对风和浪之间的非线性相互作用的理解，这对海面的生长和消散非常重要。将进行研究，以确定在什么条件下可以通过包括适当的强迫项将相互作用的复杂系统“解耦”成仅考虑气流或仅考虑流体动力的模拟；如果适用，将把这些强迫项的形式与现有的经验和分析模型进行比较，以澄清重要的物理过程。与水-气耦合模式相比，在更大尺度的问题中，波-浪能量传递效应将被用解耦的流体动力学模拟来研究，并得到平衡海面谱的结果形式。还将考虑常用的近似水动力模型来评估其性能，并将使用适用的近似模型外推从数值研究中获得的海浪频谱，以包括完整的数值模拟中未捕捉到的破碎波影响。该项目的结果将对全球气候研究、海浪预报以及直接和遥感海洋数据的解释具有重要意义。更广泛地说，项目结果将阐明在耦合的非线性湍流系统中可能发生的重要物理效应。风产生的海面波是影响全球气候的基本海气相互作用过程之一。尽管人们通过物理模型和实验测量对这一课题进行了广泛的研究，但由于气流和海面波演化中隐含的非线性现象，对所涉及的物理问题的理解仍然有限。数值模拟提供了一种提高对这一问题复杂相互作用的理解的方法，但直到最近，计算资源才得到改善，使足够大的规模模拟成为可能。拟议的项目代表了应用数学和工程研究人员之间的跨学科合作。教育工作还包括该项目的一个主要目标，包括研究生和本科生教育和研究。该项目的所有参与者将通过算法和代码开发获得信息技术(IT)经验。项目成果将通过会议和期刊出版物以及通过使用万维网向外部社区传达；项目网络资源还将用于研究小组授课的课程，向学生介绍信息技术研究的科学应用。

The proposed project develops a numerical model for turbulent airflow over nonlinearly evolving water surfaces that overcomes the limitations of previous studies. Efficient computational algorithms for modeling airflow, efficient hydrodynamic methods to evolve the sea surface boundary, and parallel computing techniques will be combined to make statistical analyses of realistic problems in both two and three dimensions possible. Scientific visualization methods will be applied to analyze results and to improve understanding of the nonlinear interactions between wind and waves that are important for sea surface growth and dissipation. Studies will be performed to determine the conditions under which "decoupling" the interacting complex systems into airflow-only or hydrodynamic-only simulations is possible by including appropriate forcing terms; the form of these forcing terms, when applicable, will be compared with existing empirical and analytical models to clarify the important physical processes. Decoupled hydrodynamic-only simulations will be pursued to investigate wave-wave energy transfer effects in larger scale problems than those possible in the coupled air-water model, and resulting forms of the equilibrium sea surface spectrum will be obtained. Commonly applied approximate hydrodynamic models will also be considered to assess their performance, and wave spectra obtained from numerical studies will be extrapolated using applicable approximate models to include breaking-wave effects not captured in the full numerical simulations. Results of the project will be significant for studies of the global climate, sea wave forecasting, and interpretation of direct and remotely sensed oceanographic data. More generally, project results will clarify important physical effects that can occur in a system of coupled nonlinear turbulent systems. The generation of sea surface waves by winds is one of the fundamental air-sea interaction processes that affect the global climate. Although this topic has been studied extensively through both physical modeling and experimental measurements, understanding of the physics involved remains limited due to the nonlinear phenomena implicit in both airflow and sea surface wave evolution. Numerical simulations offer a means to improve understanding of the complex interactions of this problem, but only recently have computing resources improved to make sufficiently large scale simulations possible. The proposed project represents an interdisciplinary collaboration between applied mathematics and engineering researchers. Educational efforts also comprise a principal objective of the project, including graduate and undergraduate education and research. All participants in the project will gain information technology (IT) experience through algorithm and code development. Project results will be communicated to the external community through conference and journal publications and through use of the world-wide-web; project web resources will also be used in classes taught by the research team to introduce students to scientific applications of IT research.