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。

• 批准号: 2023499
• 负责人: Keith Julien
• 金额: $ 36.37万
• 依托单位: University of Colorado at Boulder
• 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=2023499&HistoricalAwards=false
• 关键词: Collaborative; Research; Explorations; Salt; Finger

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.

该项目是一项关于海洋湍流双扩散的理论和计算研究。双扩散过程是由在热盐条件下的海洋中的盐度和温度扩散的不同速率/尺度引起的，这可能导致湍流混合。该项目采用渐近缩放尺度的方法来使运动方程式更具牵引力，从而促进了双重扩散的详细检查。新的渐近模型的发展提供了独特的能力，可以在极端海洋方面对盐指对流进行模拟。渐近理论的基本缩放假设还为重新恢复运动方程的新策略提供了一种在探测该制度时具有更大数值稳定性的策略。将开发新的理论，以帮助我们提高我们对盐指湍流饱和状态的理解。该项目是对小盐度与热扩散比的海洋状态有效的盐指对对流的全面研究。这是通过利用：新型渐近减少模型来实现的，这些模型将推断为极端参数设置； Navier-Stokes流体方程的新重新重新制定，该方程扩展了直接数值模拟的稳定性和计算能力；以及剖析湍流盐指的流动形态，能量和多尺度的理论分析。目前，湍流双扩散的直接数值模拟受扩散比的限制。渐近模型将采用过滤计算性过度的快速内部波并保持无惯性平衡的模型。重新经过的Navier-Stokes流体方程保持了内部重力波，但利用了空间和时间衍生物的渐进式重新分组，并允许与简化的模型进行比较。该奖项反映了NSF的法定任务，并通过使用基金会的知识优点和广泛的影响来评估，通过评估值得进行评估，并通过评估值得进行评估。

项目成果

Staircase solutions and stability in vertically confined salt-finger convection

• DOI: 10.1017/jfm.2022.865
• 发表时间: 2022-07
• 期刊: Journal of Fluid Mechanics
• 影响因子: 3.7
• 作者: Chan Liu;K. Julien;E. Knobloch

Fixed-flux salt-finger convection in the small diffusivity ratio limit

• DOI: 10.1063/5.0031071
• 发表时间: 2020-12
• 期刊: Physics of Fluids
• 影响因子: 4.6
• 作者: Jin-Han Xie;K. Julien;E. Knobloch