Physical and Computational Concepts for Systematic Development of Drag Reducing Surfaces in Pipes

管道减阻表面系统开发的物理和计算概念

• 批准号: 1335731
• 负责人: Ronald Adrian
• 金额: $ 30万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-15 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1335731&HistoricalAwards=false
• 关键词: Physical; Computational; Concepts; Systematic; Development

PI: Adrian, Ronald Proposal Number: 1335731 The broad goal of the proposed research is to investigate the structure of turbulence eddies in pipe flows for the purpose of developing passive drag reducing surfaces suitable for implementation in large-scale engineering systems such as the U. S. national network of pipelines. Despite the many drag reducing strategies that have been tried to reduce wall friction caused by turbulent flow over surfaces, it is difficult to find any clear, undisputed set of principles that explains how one should design surfaces to reduce skin friction drag. The surfaces that have been successful, such as riblets, have been devised by trial and error methods coupled with the knowledge of the simplest aspects of wall turbulence, or by bio-mimetic approaches that copy methods used by life forms such as shark skin. However, progress over the past decade in understanding the coherent structures responsible for creating friction stresses now brings the possibility of a systematic approach to drag reduction within reach. The matter of transition to turbulent flow in pipe flow is an especially vexing question that has remained open for more that a century. The answers to these questions seem likely to be essential, or at the least very valuable, to the invention of drag reducing agencies that operate by inhibiting the formation of turbulence or diminishing its strength. The specific goals are to investigate the transition to turbulence in pipe flow at Reynolds numbers well above the lower critical value; to investigate the eddy mechanisms leading to re-laminarization of accelerating turbulent flows; and to develop large eddy simulation methods capable of revealing, with high fidelity, the effects of drag reducing surfaces at high Reynolds numbers.Intellectual Merit :The transition to turbulence in pipe flow is one of the longest standing mysteries in fluid mechanics. Understanding the origins of turbulence in pipe flow will guide efforts to design drag reducing agents. Explaining the eddy mechanisms underlying the behavior of relaminarizing flow will test current physical models of wall turbulence such as the hairpin packet paradigm, and also provide insights into a form of turbulence behavior that reduces drag. Exploring singular perturbation methods for devising models for simulating high Reynolds number flow with fully resolved near-wall physics may improve our ability to simulate and model turbulent flow over surfaces, including complex drag reducing patterns.Broader Impacts :Tools that will contribute to the eventual development of drag reducing methods for pipe flow would enable economically valuable energy savings. Overcoming turbulent friction consumes a surprisingly large fraction of the United States' national energy budget. The system of pipelines carrying oil and natural gas throughout the U. S. requires 3% of the roughly 1 T$ annual energy expenditure to pump the fluids, corresponding about 30B$ per annum to overcome the flow resistance due to turbulence in the pipes.

PI: Adrian， Ronald提案号：1335731拟议研究的广泛目标是研究管道流动中的湍流涡流结构，以开发适用于大型工程系统（如美国国家管道网络）的被动减阻表面。尽管已经尝试了许多减少阻力的策略来减少由表面湍流引起的壁面摩擦，但很难找到任何明确的、无可争议的一套原则来解释如何设计表面以减少表面摩擦阻力。成功的表面，如波纹，是通过反复试验的方法，结合对壁面湍流最简单方面的了解，或通过模仿生物形式（如鲨鱼皮）的方法设计出来的。然而，在过去的十年中，在理解产生摩擦应力的连贯结构方面取得的进展，现在使减少阻力的系统方法成为可能。管流过渡到紊流的问题是一个特别棘手的问题，一个多世纪以来一直没有定论。这些问题的答案似乎是至关重要的，或者至少是非常有价值的，对于通过抑制湍流的形成或减少其强度来工作的减阻机构的发明。具体目标是研究在远高于较低临界值的雷诺数下管道流动向湍流的转变；研究加速湍流再层压化的涡动机制；并开发能够高保真地揭示高雷诺数下减阻表面影响的大涡模拟方法。智力价值：管道流动向湍流的转变是流体力学中长期存在的谜团之一。了解管道流动中湍流的起源将指导设计减阻剂。解释再层流行为背后的涡流机制，将测试当前壁面湍流的物理模型，如发夹包范式，并为减少阻力的湍流行为形式提供见解。探索奇异摄动方法来设计模拟高雷诺数流动的模型，具有完全分解的近壁物理，可以提高我们模拟和模拟表面湍流的能力，包括复杂的减阻模式。更广泛的影响：有助于最终开发管流减阻方法的工具将实现经济上有价值的能源节约。克服湍流摩擦消耗了美国国家能源预算的很大一部分。在美国，输送石油和天然气的管道系统每年需要大约1万亿美元的能源支出中的3%用于泵送流体，相当于每年大约300亿美元用于克服管道湍流引起的流动阻力。