Effects of hydrophobicity-induced wall slip on turbulence drag and turbulence structure

疏水性引起的壁滑移对湍流阻力和湍流结构的影响

• 批准号: 0853657
• 负责人: Dimitrios Papavassiliou
• 金额: $ 23万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0853657&HistoricalAwards=false
• 关键词: Effects; hydrophobicity; induced; wall; slip

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). CBET -0853657 Papavassiliou, Dimitrios V.This project will investigate the fundamental molecular mechanisms that can result in fluid slip at a solid-fluid interface and how exactly, if at all, fluid slip affects the structure of turbulence away from the viscous wall sublayer. It has been recently documented that ultra-hydrophobic surfaces induce slip in fluids moving over them. For laminar flows, this slip at the wall results in drag reduction that has been observed both experimentally and computationally. Recent computational work shows that ultra-hydrophobic surfaces can lead to turbulent drag reduction only when they result in significant fluid slip at the wall. Turbulent drag reduction has been achieved with the introduction of a very small amount of additives, such as polymers, surfactants or microbubbles. Such methods are mainly feasible for internal flows. However, when a fluid flows around an object, the use of additives to alter the fluid properties is at best impractical. If treating a conduit (or a vehicle) surface such that it becomes ultra-hydrophobic can result in drag reduction, then such treatment will present a drag-reduction technology feasible for both internal and external flows. This study is focused on the fundamental investigation of the conditions that generate fluid slip at the solid-water interface, and the effects that such slip can have on turbulence drag reduction. Specific issues to be investigated include the correlation between hydrophobicity and fluid slip and its interpretation based on the molecular structure of the fluid next to a solid-fluid interface, the exploration of the type of fluid and the type of interface that can result in fluid slip, and the determination of the mechanism by which slip affects the generation and maintenance of turbulence. These findings will be significant for the theory of fluid flow next to solid surfaces and for turbulence, as well as for many industrial applications. Aspects of this research project will be instrumental in the development of a new course and will be integrated in existing courses. In addition, the database generated through this project will become available to the community through existing web servers, and databases that can serve as validation benchmarks are planned.

该奖项是根据2009年《美国复苏与再投资法》（公法111-5）资助的。 CBET -0853657 PAPAVASLIOU，DIMITRIOS V.本项目将研究基本的分子机制，这些机制可能会导致固体流体界面处的流体滑移，以及如果有的话，流体滑移的确会影响湍流的结构，使湍流从粘性壁sublayer sublayer sublayer。最近有记载的是，超血液表面会在其上移动的液体中诱导滑动。对于层流的流动，墙壁上的这种滑动导致拖动减小，这在实验和计算上都被观察到。最近的计算工作表明，只有在壁上导致大量的流体滑移时，超血表面才会导致湍流减少。 通过引入非常少量的添加剂，例如聚合物，表面活性剂或微泡。这种方法主要对于内部流动是可行的。但是，当流体在物体周围流动时，使用添加剂来改变流体特性充其量是不切实际的。如果处理导管（或车辆）表面以使其变为超干燥恐惧症会导致阻力减少，那么这种处理将对内部和外部流动可行的拖曳减少技术。 这项研究的重点是对在固体水界面产生流体滑移的条件的基本研究，以及这种滑动对减少湍流阻力的影响。要研究的具体问题包括疏水性与流体滑移之间的相关性及其基于固体融合界面旁边流体的分子结构的解释，探索流体类型和界面的类型，可以导致流体滑移的类型，以及机制对机制的确定影响，而滑移会影响和维持湍流的产生和维护。 这些发现对于固体表面和湍流以及许多工业应用的流体流程理论将很重要。该研究项目的各个方面将有助于开发新课程，并将集成在现有课程中。此外，通过现有的Web服务器将通过该项目生成的数据库可用于社区，并且计划可以用作验证基准测试的数据库。