Collaborative Research: Large Eddy Simulations of Estuarine Mixing

合作研究：河口混合的大涡模拟

• 批准号: 0451740
• 负责人: Wayne Geyer
• 金额: $ 15.35万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-03-01 至 2009-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0451740&HistoricalAwards=false
• 关键词: Collaborative; Research; Large; Eddy; Simulations

OCE-0451699/04521740/0452380New Large Eddy Simulations (LES) will be conducted to investigate turbulent mixing processes in estuaries and coastal oceans. Temperature and salinity equations will be added to an advanced LES code that has been validated in engineering flows. The model will include LES equations generalized to incorporate large-scale density and pressure gradients, non-uniform meshes in two directions, allowing for fine resolution of the stratified pycnocline and other regions of interest, and an immersed-boundary method to represent variable-bottom bathymetry and curvy coastlines. This LES model will investigate three important mixing processes in estuaries: (1) asymmetric tidal mixing due to baroclinic pressure gradient and tidal straining; (2) mixing and lateral circulation in a straight, stratified channel with transversely varying bottom depth; (3) topographically-forced, localized mixing in hydraulic transitional flows near channel constrictions. Finally, we shall use the LES model to simulate a segment of the Hudson River estuary and compare the model results with recent dye-release experiments; the velocity and scalar fields obtained from the LES will be used to interpret observations collected in this partially-mixed estuary. The objectives of the proposed research are to elucidate turbulent mixing processes in stratified estuarine flows and to extend LES modeling techniques to horizontally-inhomogeneous estuarine and coastal flows affected by varying bathymetry and shoreline geometry.Intellectual merit: Understanding turbulent mixing in stratified shear flows is a fundamental problem in physical oceanography. Partially-mixed estuaries are an excellent natural laboratory for studying stratified turbulence, and elucidating key turbulent processes affecting salt and momentum transports in estuaries will shed light on the important mixing problem. LES techniques have been used successfully to investigate oceanic boundary layers; however, they are generally limited to horizontally-homogeneous flows in simple geometries. The methodology to be developed in this project can be used to tackle a wide range of turbulent mixing problems in coastal oceanography and generate turbulence data for calibrating and improving turbulence parameterization schemes.Broader impact: The proposed study will lead to improved representations of turbulent mixing processes in regional ocean models, which are used to predict sea level, currents, water quality, contaminant transport, and ecosystem productivity in estuarine and coastal environments of societal concerns. Biogeochemical state variables can be added into the model to investigate ecological hotspots such as harmful algal blooms in estuaries and coastal oceans. The project will provide training for a graduate student and a postdoctoral fellow to acquire advanced numerical skills for solving oceanographic problems.

新大涡模拟（LES）将用于研究河口和沿海海洋的湍流混合过程。温度和盐度方程将添加到先进的LES代码中，该代码已在工程流程中得到验证。该模型将包括广义的LES方程，以结合大规模密度和压力梯度，两个方向的非均匀网格，允许分层斜斜和其他感兴趣的区域的精细分辨率，以及浸入式边界方法，以表示变底水深和弯曲的海岸线。该LES模型将研究河口的三个重要混合过程：(1)斜压压力梯度和潮汐应变引起的不对称潮汐混合；(2)底部深度横向变化的直层状河道内的混合和横向环流；(3)在靠近河道狭窄处的水力过渡流中，地形强迫的局部混合。最后，我们将使用LES模型模拟哈德逊河河口的一段，并将模型结果与最近的染料释放实验结果进行比较；从LES获得的速度场和标量场将用于解释在这个部分混合的河口收集的观测结果。提出的研究目标是阐明分层河口流动中的湍流混合过程，并将LES建模技术扩展到受不同水深和海岸线几何形状影响的水平非均匀河口和海岸流动。知识价值：理解分层切变流中的湍流混合是物理海洋学中的一个基本问题。部分混合河口是研究分层湍流的良好天然实验室，阐明影响河口盐和动量输运的关键湍流过程将有助于解决重要的混合问题。LES技术已成功地用于研究海洋边界层；然而，它们通常仅限于简单几何形状的水平均匀流。本项目将开发的方法可用于解决沿海海洋学中广泛的湍流混合问题，并为校准和改进湍流参数化方案生成湍流数据。更广泛的影响：拟议的研究将改进区域海洋模型中湍流混合过程的表示，这些模型用于预测社会关注的河口和沿海环境中的海平面、水流、水质、污染物运输和生态系统生产力。可以在模型中加入生物地球化学状态变量，以研究河口和沿海海洋的有害藻华等生态热点。该项目将为一名研究生和一名博士后提供培训，以获得解决海洋学问题的高级数值技能。