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Collaborative Research: Explorations of Salt Finger Convection in the Extreme Oceanic Parameter Regime: An Asymptotic Modeling Approach.

合作研究：极端海洋参数体系中盐指对流的探索：渐近建模方法。

基本信息

批准号：
2023541
负责人：
Edgar Knobloch
金额：
$ 37.59万
依托单位：
University of California-Berkeley
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-09-01 至 2024-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2023541&HistoricalAwards=false
关键词：
Collaborative Research Explorations Salt Finger

项目摘要

This project is a theoretical and computational study of turbulent double diffusion in the ocean. Double diffusion processes arise from the different rates/scales of salinity and temperature diffusion in the ocean under thermohaline conditions that can lead to turbulent mixing. The project employs asymptotic scaling approaches to render the equations of motion more tractable, facilitating detailed examinations of double diffusion. The development of new asymptotic models provides a unique capability to perform simulations of the salt-finger convection in the extreme oceanic regime. The underlying scaling assumptions of the asymptotic theory also provide a new strategy for rescaling the oceanic equations of motion that allows for greater numerical stability in probing this regime. New theories will be developed to help improve our understanding of the saturated states of salt-finger turbulence. This project is a comprehensive study of salt-finger convection valid in the oceanic regime of small salinity to thermal diffusivity ratio. This is accomplished by utilizing: novel asymptotically reduced models that extrapolate to extreme parameter settings; a new reformulation of the Navier-Stokes fluid equations that extends the stability and computational capabilities of direct numerical simulations; and theoretical analysis that dissects the flow morphology, energetics and multiscale nature of turbulent salt fingers. At present, direct numerical simulations of turbulent double diffusion are limited by the diffusivity ratio. Asymptotic models which filter computationally prohibitive fast internal waves and maintain an inertia-free balance will be employed. The reformulated Navier-Stokes fluid equations retain internal gravity waves but utilize the asymptotic rescalings of the spatial and temporal derivatives and field magnitudes and allow for comparison with reduced models.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

本项目是海洋湍流双扩散的理论与计算研究。双扩散过程产生于热盐条件下海洋中盐度和温度扩散的不同速率/尺度，这可能导致湍流混合。该项目采用渐近缩放方法使运动方程更易于处理，便于对双重扩散进行详细检查。新的渐近模式的发展为模拟极端海洋状态下的盐指对流提供了独特的能力。渐近理论的基本尺度假设也为海洋运动方程的重新尺度提供了一种新的策略，允许在探测该状态时具有更大的数值稳定性。新的理论将被开发出来，以帮助提高我们对盐指湍流饱和状态的理解。本项目是对小盐度热扩散比海洋条件下有效的盐指对流的综合研究。这是通过利用新的渐近简化模型来实现的，该模型外推到极端参数设置；Navier-Stokes流体方程的新重新表述，扩展了直接数值模拟的稳定性和计算能力；理论分析，剖析了紊流盐指的流动形态、能量学和多尺度性质。目前，紊流双扩散的直接数值模拟受到扩散率的限制。将采用渐近模型来过滤计算上禁止的快速内波并保持无惯性平衡。重新表述的Navier-Stokes流体方程保留了内部重力波，但利用了空间和时间导数和场强的渐近重标度，并允许与简化模型进行比较。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。