Molecular Tagging Techniques for Stratified Flow: Application to Boundary Mixing

[67270 . rehmann]热、盐和污染物的传输对于测量和预测环境流是很重要的。例如，湖泊的水质取决于热量和污染物的垂直输送，而海洋中热量和盐的输送影响全球气候。为了改进输运的测量和建模，已经在其他工程流中成功应用的分子标记速度和温度测量（MTV&amp；T）将扩展到分层流中的应用。该技术将应用于一个实验室模型中，该模型是由湖泊和海洋边界的内波驱动的混合。该项目的具体目标是：(1)将MTV&amp；T扩展到盐层流；(2)量化长波产生的湍流和混合；(3)确定间歇强迫对混合和输运的影响。所提出的研究的智力价值来自于能够比以前更详细地测量由内波产生的边界层中的混合和湍流；MTV&amp；T将提供速度、浓度和通量的二维场，同时避免其他技术的一些缺陷。拟议的实验室实验从一个充分研究的案例开始，以验证分子标记技术，然后扩展先前的实验室工作，以研究在解释现场测量中重要的其他因素。同时进行的现场测量将指导实验室实验的设计，并测试实验室的结果。提出的工作利用了PI Rehmann在边界混合的测量和建模方面的经验。在先进的流量测量和可视化技术方面的专业知识。更广泛的影响包括培训研究生，开展与学校的联系，以及将分子标记方法应用于分层流。这种拓展利用了雷曼和胡与爱荷华州的学校和项目建立的联系，扩大了未被充分代表的群体的参与。此外，拟议的项目涉及首次将分子标记方法应用于具有环境重要性的分层流；由于以前的野外测量表明，边界混合可以控制湖泊和海洋中整个盆地的垂直输送，这些实验将为模拟环境中的污染物输送提供有价值的信息。此外，一旦提出的工作证明了分子标记对边界混合的有用性，它就可以用于环境中许多其他分层流动的实验室模型。

1067270RehmannThe transport of heat, salt, and contaminants is important to measure and predict in environmental flows. For example, water quality in lakes depends on vertical transport of heat and contaminants, and the transport of heat and salt in the ocean affects the global climate. To improve the measurement and modeling of transport, molecular tagging velocimetry and thermometry (MTV&T), which has been applied successfully in other engineering flows, will be extended for use in stratified flows. The technique will be applied in a laboratory model of mixing driven by internal waves at the boundary of lakes and oceans. Specific objectives of the project are to (1) extend MTV&T to salt-stratified flow, (2) quantify turbulence and mixing generated by long waves, and (3) determine the effect of intermittent forcing on the mixing and transport.The intellectual merit of the proposed research comes from the ability to measure the mixing and turbulence in a boundary layer generated by internal waves in more detail than previously possible; MTV&T will provide two-dimensional fields of velocity, concentration, and flux while avoiding some of the pitfalls of other techniques. The proposed laboratory experiments start with a well-studied case to verify the molecular tagging technique and then extend previous laboratory work to study other factors that are important in interpreting field measurements. Concurrent field measurements will guide the design of the laboratory experiments and test the results from the lab. The proposed work exploits PI Rehmann's experience with measurements and modeling of boundary mixing and PI Hu?s expertise in advanced flow measurement and visualization techniques. The broader impacts include training a graduate student, conducting outreach to schools, and applying molecular tagging methods to stratified flow. The outreach uses the connections that Rehmann and Hu have established with Iowa schools and programs to broaden the participation of underrepresented groups. Also, the proposed project involves the first application of the molecular tagging method to a stratified flow of environmental importance; because previous field measurements have shown that boundary mixing can control the basin-wide vertical transport in lakes and oceans, these experiments will provide valuable information for modeling contaminant transport in the environment. Furthermore, once the proposed work demonstrates the usefulness of molecular tagging for boundary mixing, it can be used in laboratory models of many other stratified flows in the environment.