Collaborative Research: Double-diffusive sedimentation

合作研究：双扩散沉降

• 批准号: 1438052
• 负责人: Eckart Meiburg
• 金额: $ 20.6万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2017-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1438052&HistoricalAwards=false
• 关键词: Collaborative; Research; Double; diffusive; sedimentation

CBET 1438052/1437275This project will use theory, numerical simulation, and experiments to study the motion that is induced by instabilities in stratified liquid systems. For example, when fresh water from a river enters the ocean, concentration gradients of sediment and salt form simultaneously. Under certain conditions that can be predicted theoretically, the presence of these gradients leads to an unstable situation that induces convective motion of the sediment-laden water. Preliminary results show that this motion strongly affects the settling velocity and transport of the sediment. This project will develop a framework for analyzing motions induced by such instabilities in a variety of situations pertaining to river estuaries. However, the framework will be more broadly applicable to problems in environmental, geophysical, astrophysical, and engineering flows. This collaborative project will use theoretical, computational, and experimental tools to explore the linear and nonlinear dynamics of double diffusive sedimentation under a wide range of conditions. Linear stability theory, direct numerical simulation, and laboratory experiments will be conducted for four basic configurations: a) a layer of sediment-laden fresh water above saline water; b) a layer of sediment-laden fresh water below saline water; c) linear concentration gradients with sediment being unstably stratified; d) linear concentration gradients with sediment being stably stratified. Effects of shear flow in the water, which is appropriate for river estuaries, will be included. The research will address a range of interesting phenomena observed in these systems including fingering instabilities, horizontal intrusions, and staircases formed in particulate systems. The proposed research will identify dominant instability mechanisms in various parameter regimes, and will provide quantitative scaling laws for double diffusive sedimentation in each case.

CBET 1438052/1437275这项项目将使用理论，数值模拟和实验来研究由分层液体系统中不稳定性引起的运动。 例如，当河中的淡水进入海洋时，同时形成沉积物和盐的浓度梯度。 在理论上可以预测的某些条件下，这些梯度的存在导致不稳定的情况，从而引起了含沉积物的水的对流运动。 初步结果表明，这种运动强烈影响沉积物的沉降速度和运输。 该项目将开发一个框架，用于分析与河流有关的各种情况下这种不稳定性引起的动议。 但是，该框架将更广泛地适用于环境，地球物理，天体物理和工程流的问题。该协作项目将使用理论，计算和实验工具来探索在广泛条件下双重扩散沉积的线性和非线性动力学。 将针对四种基本配置进行线性稳定性理论，直接数值模拟和实验室实验：a）一层盐水上方的含沉积物的淡水； b）盐水下方的一层含沉积物的淡水； C）线性浓度梯度的沉积物不稳定地分层； d）稳定分层的线性浓度梯度。 将包括适合河流河口的水中剪切流的影响。 这项研究将解决在这些系统中观察到的一系列有趣现象，包括指法不稳定性，水平侵入和在颗粒系统中形成的楼梯。 拟议的研究将确定各种参数制度中的主要不稳定性机制，并在每种情况下为双扩散沉积提供定量缩放定律。