Global conservation of momentum applied to environmental flows

应用于环境流的全球动量守恒

• 批准号: EP/G055602/1
• 负责人: Ian Eames
• 金额: $ 0.75万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FG055602%2F1
• 关键词: Global; conservation; momentum; applied; environmental

The application of global momentum conservation principles to multiphase flows is a relatively new approach to understand what happens when discrete elements move and disappear (see references in Part 1). This is important, for instance, when vapour bubbles rise and condense, or fuel droplets move and evaporate. After the elements have disappeared (in the sense that there is no boundary on which the kinematic condition is applied), a vortex is left behind. The momentum approach enables the final state of the flow signature and properties of the vortex to related to the initial properties of the droplets or the history of forces acting on the bubbles. These ideas and concepts have been tested experimentally and theoretically, and the framework is complete for the case of linear momentum.The aim of this current proposal is to extend this research to problems in environmental fluids mechanics. Specifically there are two areas of interest here : free surface flows and self-propelled bodies. Quantifying the momentum of wave is known to be fraught with problems; for wave trains it is more usual to discuss momentum flux [1]. One area where applying momentum conservation might be useful is the problem of compact local wave groups or tsunamis. The second area of interest is in self-propelled bodies, such as submarines. The critical issue is the flow signature they generate when they move unsteadily and whether these signatures can be detected. Both these problems are important in their own right and some aspects may be understood by applying global conservation of momentum. The key problem is setting down the conceptual framework in a rigorous manner and to test these ideas experimentally.The importance of visiting Arizona State University is underlined by two research areas in which it leads internationally: (a) Depressed tsunami dynamics. Tsunami research is currently quite active owing to the devistating effect of the Indian Ocean tsunami December 25th 2006. Prof Fernando (ASU) led the NSF scientific fact-finding group to Sri-Lanka and the results have been disseminated quite widely. One of the key aspects of their recent experimental work on depressed tsunamis was the ability to remove the tail of the depressed tsunami using, what they refer to as a leaky paddle . The experimental work was undertaken a DTA student from UCL who stayed at ASU for 3 months. (b) Subsurface signatures generated by moving submarines. Voropayev and his colleagues have been particularly active in this area having published half a dozen papers on the topic in the last few years. Voropayev is a leader in the vortex dynamics in stratified and homogeneous fluids and he has developed a very general understanding of the develop of vortex signatures interacting with the free surface, caused by the unsteady rectilinear motion of a submarine (modelled as a jet). Using similarity theory and scaling analysis enabled Voropayev to make some clear statements about the revealing surface signatures.

将全局动量守恒原理应用于多相流是一种相对较新的方法，用于了解离散元素移动和消失时会发生什么（请参阅第 1 部分中的参考资料）。例如，当气泡上升并凝结，或者燃料滴移动并蒸发时，这一点很重要。元素消失后（即没有应用运动学条件的边界），会留下一个涡流。动量方法使流动特征和涡流特性的最终状态与液滴的初始特性或作用在气泡上的力的历史相关。这些想法和概念已经过实验和理论上的检验，并且线性动量情况的框架是完整的。当前提案的目的是将这项研究扩展到环境流体力学问题。具体来说，这里有两个令人感兴趣的领域：自由表面流和自推进体。众所周知，量化波的动量充满了问题。对于波列，更常见的是讨论动量通量 [1]。应用动量守恒可能有用的一个领域是紧凑的局部波浪群或海啸问题。第二个感兴趣的领域是自推进体，例如潜艇。关键问题是它们不稳定移动时产生的流动特征以及这些特征是否可以被检测到。这两个问题本身都很重要，并且某些方面可以通过应用全局动量守恒来理解。关键问题是以严格的方式建立概念框架并通过实验检验这些想法。亚利桑那州立大学在国际上处于领先地位的两个研究领域强调了访问亚利桑那州立大学的重要性：(a) 抑制海啸动力学。由于2006年12月25日印度洋海啸的破坏性影响，海啸研究目前相当活跃。费尔南多教授（亚利桑那州立大学）带领国家科学基金会科学事实调查组前往斯里兰卡，研究结果得到了广泛传播。他们最近关于低气压海啸的实验工作的关键方面之一是能够使用他们所说的漏桨去除低气压海啸的尾部。实验工作由一名来自 UCL 的 DTA 学生承担，他在 ASU 呆了 3 个月。 (b) 移动的潜艇产生的地下特征。沃罗帕耶夫和他的同事在这一领域特别活跃，在过去几年中发表了六篇有关该主题的论文。沃罗帕耶夫是分层均质流体涡动力学领域的领军人物，他对由潜艇（建模为喷气机）的不稳定直线运动引起的与自由表面相互作用的涡旋特征的发展有了非常全面的理解。利用相似理论和尺度分析，沃罗帕耶夫能够对揭示的表面特征做出一些清晰的陈述。