COLLABORATIVE RESEARCH: Fingering convection at low Prandtl number

合作研究：低普朗特数下的指对对流

• 批准号: 0933057
• 负责人: Timour Radko
• 金额: $ 10万
• 依托单位: Naval Postgraduate School
• 依托单位国家: 美国
• 项目类别: Interagency Agreement
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0933057&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Fingering; convection; low

CBET - 0933759 /0933057 Garaud / Radko Fingering convection at low Prandtl number. Double-diffusive processes play an important role in mixing the upper ocean, and have been extensively studied in this context. Decades of experimental and theoretical research in the high-Prandtl (Pr) number regime characteristic of the heat/salt system have provided reliable parametrizations for the turbulent heat and salt fluxes induced by double-diffusive instabilities, as well as insight into the mechanisms leading to the formation of thermohaline staircases. Double-diffusive mixing is also thought to play a major role in the astrophysical context, and in particular in the interior of stars and giant planets. However, the applicability of parametrizations and analytical theories derived in the high-Pr regime to other regions of parameter space remains an entirely open question. Indeed, studies of the characteristics of linear and weakly nonlinear double-diffusive instability suggest that the low- Pr regime appropriate to the astrophysical context bears little resemblance to the aforementioned heat-salt system. The mechanism causing the saturation of the fingering instability is still undetermined; whether fingering convection leads to the formation of thermochemical staircases or not is an entirely open question. In short, double-diffusive transport remains one of the most uncertain components of global stellar/planetary evolution models. In this study, The PIs plan to carry out an extensive numerical and analytical study of fingering convection in the context of stellar/planetary interiors (Pr'á 1), address the points raised above and derive practical parametric formulae for the heat and compositional fluxes for use by the astrophysical community in global evolution models. The numerical tool the PIs intend to use has already been developed in the scope of a related but different NSF-funded study. Using this tool, the PI's team obtained the first ever evidence for 3D spontaneous thermohaline staircase formation. Since no low-Pr, 3D Direct Numerical Simulations of fingering convection have ever been performed, the PI's experimental results will be an invaluable point of comparison for all existing and future theories. The analytical tools the PIs intend to develop will be inspired by, and thus strive to extend, existing high-Pr work. Both astrophysical and oceanographic communities, supported by state-of- the-art numerical tools, will greatly benefit from this interaction. This study will contribute to UC-wide efforts in the development of the Fluid Dynamics and High-Performance Computing curricula by providing the opportunities for undergraduate training in research (Senior Thesis projects, and UC LEADS research opportunities) and by contributing to the construction of a fluid dynamics student experimental laboratory with inquiry-based learning educational techniques (as part of the Institute for Science and Engineer Educators program).

CBET -0933759 /0933057 GARAUD / RADKO指法对流在低printtl编号。双扩展过程在混合上海中起着重要作用，并且在这种情况下已广泛研究。热/盐系统的高丙助器数（PR）数量特征的实验和理论研究数十年为可靠的参数提供了可靠的参数，以引起双重延伸不稳定引起的湍流和盐通量，并深入了解导致热钙阶段形成的机制。两次延伸的混合也被认为在天体物理背景中，尤其是恒星和巨型行星的内部。但是，在高PR制度中得出的参数和分析理论的适用性仍然是一个完全开放的问题。确实，对线性和弱非线性双扩散不稳定性的特征的研究表明，适合天体物理环境的低PR政权与近似热盐系统几乎没有相似之处。导致指法不稳定性饱和的机制仍未确定；指法连接是否导致热化学楼梯的形成是一个完全开放的问题。简而言之，两次扩散运输仍然是全球恒星/行星演化模型中最不确定的组成部分之一。在这项研究中，PIS计划在恒星/行星内部的背景下对指法连接进行广泛的数值和分析研究（Pr'á1），解决上述点的点，并为全球进化模型中的热量和复合磁通提供实用的热量和复合磁通量。 PIS打算使用的数值工具已经在相关但不同的NSF资助研究的范围内开发出来。使用此工具，PI的团队获得了3D赞助热盐楼梯组的第一个证据。由于从未执行过低PR的3D直接数值模拟，因此PI的实验结果将是所有现有理论和未来理论的宝贵比较点。 PIS打算开发的分析工具将受到现有的高PR工作的启发，从而努力扩展。由最先进的数值工具支持的天体物理和海洋学社区都将从这种互动中受益匪浅。 This study will contribute to UC-wide efforts in the development of the Fluid Dynamics and High-Performance Computing curricula by providing the opportunities for undergraduate training in research (Senior Thesis projects, and UC LEADS research opportunities) and by contributing to the construction of a fluid dynamics student experimental laboratory with inquiry-based learning educational techniques (as part of the Institute for Science and Engineer Educators program).