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Horizontal convection: the role of turbulence

水平对流：湍流的作用

基本信息

批准号：
0926481
负责人：
Stefan Llewellyn Smith
金额：
$ 51.99万
依托单位：
University of California-San Diego
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2009
资助国家：
美国
起止时间：
2009-09-15 至 2013-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=0926481&HistoricalAwards=false
关键词：
Horizontal convection role turbulence

项目摘要

Intellectual Merit: Horizontal convection is the generic designation for the circulation resulting from differential heating along one horizontal boundary of a fluid. It is a key feature of the ocean's Meridional Overturning Circulation. The full problem of the Meridional Overturning Circualtion is complex and difficult, involving thermal, haline, and mechanical forcing. Understanding the simpler problem of (single-component) horizontal convection is an important step in attacking the full problem. Mixing is critically important in producing a pathway for cold water to be modified and return to the surface. Molecular processes are far too puny to carry out this role. The role of turbulence in horizontal convection is hence crucial.The laboratory and numerical experiments on horizontal convection will address five hypotheses:1. Scaling for the boundary-layer thicknesses of previous work is correct. 2. Dissipation is highly variable in space. 3. The boundary between steady and unsteady regimes is a function of aspect ratio, dimensionality, and rotation. 4. Small-scale variability of the boundary forcing should shut down large-scale convection. 5. Combined buoyancy and mechanical forcing changes the regime diagram.Broader Impacts: The investigators will engage in educational activities at multiple levels. The environmental fluid dynamics laboratory, in which the lead investigator works, has a strong track record in undergraduate mentoring. They will recruit an undergraduate and will work with UCSD's McNair Program and/or the Summer Training Academy for Research in the Sciences (STARS) program, both of which target students are from groups traditionally underrepresented in the sciences. The research will involve two graduate students. Reaching pre-college students will contribute to the professional development of high school teachers in the San Diego Unified School District. In partnership with the NSF-funded Center for Ocean Science Education Excellence/California they will sponsor a one-day workshop for approximately 25 Earth sciences teachers. The investigators will contribute to the Wiki page of the CFD code chosen for this work. These posts will broadly disseminate key results of NSF-funded work in a venue that is accessed by the larger CFD community, thus enhancing scientific and technological understanding. The results of the project have applications in industry and to environmental sustainability, as well as in related fields of science, in particular limnology and climate science. The experiments carried out here are relevant to natural ventilation of buildings. Improved understanding of the fluid mechanics of natural ventilation, an anticipated outcome of the project, can inform critical energy conservation efforts that may ultimately benefit society economically, environmentally and politically.

智力优势：水平对流是流体沿沿着一个水平边界的差热循环的总称。它是海洋经向翻转环流的一个关键特征。子午翻转圈的全部问题是复杂而困难的，涉及热力、盐和机械力。理解（单组分）水平对流的简单问题是解决整个问题的重要一步。混合对于产生一条使冷水被改变并返回表面的路径至关重要。分子过程太弱小了，无法发挥这一作用。湍流在水平对流中的作用是至关重要的。水平对流的实验室和数值实验将解决五个假设：1。以前工作中边界层厚度的比例是正确的。2.耗散在空间中变化很大。3.定常和非定常区域之间的边界是纵横比、维数和旋转的函数。4.边界强迫的小尺度变率应该关闭大尺度对流。5.浮力和机械力的组合改变了状态图。更广泛的影响：调查人员将在多个层面上从事教育活动。首席研究员所在的环境流体动力学实验室在本科生指导方面有着良好的记录。他们将招募一名本科生，并将与UCSD的McNair计划和/或科学研究暑期培训学院（STARS）计划合作，这两个计划的目标学生都来自传统上在科学领域代表性不足的群体。这项研究将涉及两名研究生。接触大学预科学生将有助于圣地亚哥联合学区高中教师的专业发展。与NSF资助的海洋科学教育卓越中心/加州合作，他们将为大约25名地球科学教师举办为期一天的研讨会。研究人员将为这项工作选择的CFD代码的Wiki页面做出贡献。这些职位将在更大的CFD社区访问的场所广泛传播NSF资助的工作的关键成果，从而提高科学和技术的理解。该项目的成果可应用于工业和环境可持续性，以及相关的科学领域，特别是湖沼学和气候科学。本文所做的实验与建筑物的自然通风有关。该项目的预期成果之一是提高对自然通风流体力学的理解，这可以为关键的节能工作提供信息，最终可能在经济、环境和政治上造福社会。