EAGER: Collaborative Research: Exploring the inverse cascade in two-dimensional turbulent soap films

EAGER：协作研究：探索二维湍流肥皂膜中的逆级联

• 批准号: 1044901
• 负责人: Nigel Goldenfeld
• 金额: $ 15.8万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1044901&HistoricalAwards=false
• 关键词: EAGER; Collaborative; Research; Exploring; inverse

NON-TECHNICAL ABSTRACT: Turbulent flows past a wall experience frictional drag, the property of a flow that sets the cost of pumping oil through a pipeline, the draining capacity of a river in flood, and other quantities of practical interest. Much is known about the frictional drag, mostly from extensive experiments in which the frictional drag was measured in pipes or open channels, yet, there has been no known link between the frictional drag and the statistics of the turbulent eddies in the flow. The project' goal is to test experimentally a recently proposed theory that will allow us to predict the frictional drag from a knowledge of the statistics of the turbulent eddies. This will be achieved through measurements in a type of two-dimensional turbulent flow that may be realized in very thin soap films, where it is possible to create flows with different types of statistics. If confirmed, the theory could provide the key to understanding the drag-altering effects of polymeric additives used in oil pipelines, particulate suspensions found in rivers in flood, entrained bubbles found in water-treatment plants, and other agents known to affect the statistics of the flow. At Illinois and Pittsburgh, graduate and undergraduate students will be trained with a multidisciplinary focus encompassing engineering and fundamental condensed matter physics, introducing undergraduates and women to research in turbulence. The PIs will collaborate on outreach to grades 6-12, work with an all-girl's middle school to devise a unit on soap film physics, turbulence, chaos and optics, and participate in a teacher's workshop.TECHNICAL ABSTRACT: Turbulent flows past a wall experience frictional drag, the property of a flow that sets the cost of pumping oil through a pipeline, the draining capacity of a river in flood, and other quantities of practical interest. While much is known about the frictional drag, there has been no known link between the frictional drag and the turbulent spectrum (i.e., the statistics of turbulent fluctuations in the flow). The goal of this project is to test experimentally a recently proposed theory that would provide the missing "spectral link". If confirmed, the theory could prove key to understanding the drag-altering effects of polymeric additives used in oil pipelines, particulate suspensions found in rivers in flood, entrained bubbles found in water-treatment plants, and other agents known to affect the spectrum. The theory has been tested in two-dimensional soap-film turbulent flows with the type of spectrum known as the enstrophy cascade, but so far it has not been possible to create similar flows with the type of spectrum known as the inverse energy cascade. A method to create soap-film flows with the inverse energy cascade will be developed; it will then be used to measure the frictional drag of inverse cascade dominated 2D turbulence, completing the experimental verification of the spectral link. At Illinois and Pittsburgh, the PIs will train graduate and undergraduate students with a multidisciplinary focus encompassing engineering and fundamental condensed matter physics, introducing undergraduates and women to research in turbulence. The PIs will collaborate on outreach to grades 6-12, working with an all-girl's middle school to devise a unit on soap film physics, turbulence, chaos and optics, and participating in a teacher's workshop.

非技术摘要：穿过墙壁的湍流会经历摩擦阻力，这是一种流动特性，它决定了通过管道泵油的成本、洪水中河流的排水能力以及其他实际意义的量。人们对摩擦阻力了解很多，主要来自在管道或明渠中测量摩擦阻力的大量实验，然而，摩擦阻力与流动中湍流涡流的统计数据之间尚不存在已知的联系。该项目的目标是通过实验测试最近提出的理论，该理论将使我们能够根据湍流涡流的统计数据来预测摩擦阻力。这将通过在一种二维湍流中进行测量来实现，这种二维湍流可以在非常薄的肥皂膜中实现，在肥皂膜中可以创建具有不同类型统计数据的流动。如果得到证实，该理论可以为理解石油管道中使用的聚合物添加剂、洪水中河流中发现的颗粒悬浮物、水处理厂中发现的夹带气泡以及已知影响流量统计的其他物质的阻力改变效应提供关键。在伊利诺伊州和匹兹堡，研究生和本科生将接受多学科培训，包括工程和基础凝聚态物理，向本科生和女性介绍湍流研究。 PI 将合作开展 6 至 12 年级的推广工作，与一所女子中学合作，设计一个有关肥皂膜物理、湍流、混沌和光学的单元，并参加教师研讨会。 技术摘要：流过墙壁的湍流会受到摩擦阻力、确定通过管道泵油成本的流动特性、洪水中河流的排水能力以及其他实际感兴趣的量。虽然人们对摩擦阻力了解很多，但摩擦阻力和湍流谱（即流动中湍流波动的统计数据）之间尚不存在已知的联系。该项目的目标是通过实验测试最近提出的理论，该理论将提供缺失的“光谱链接”。 如果得到证实，该理论可能成为理解石油管道中使用的聚合物添加剂、洪水中河流中发现的颗粒悬浮物、水处理厂中发现的夹带气泡以及已知影响频谱的其他试剂的阻力改变效应的关键。该理论已经在二维皂膜湍流中进行了测试，其频谱类型称为熵级联，但到目前为止，还不可能创建类似的流动，其频谱类型称为逆能量级联。 将开发一种利用逆能量级联产生皂膜流的方法；然后将用于测量逆级联主导的二维湍流的摩擦阻力，完成光谱链路的实验验证。 在伊利诺伊州和匹兹堡，PI 将培训研究生和本科生，重点关注工程和基础凝聚态物理等多学科，向本科生和女性介绍湍流研究。 PI 将合作向 6 至 12 年级的学生进行推广，与一所女子中学合作设计一个有关肥皂膜物理、湍流、混沌和光学的单元，并参加教师研讨会。