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Control of near-wall turbulence via slip and transpiration

通过滑移和蒸腾控制近壁湍流

基本信息

批准号：
1965893
负责人：
金额：
--
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-1965893
关键词：
Control near wall turbulence via

项目摘要

Turbulent motions near the wall are dominated by a quasi-cyclic, self-sustaining process driven by the interaction between two key coherent structures: quasi-streamwise vortices and streaks. This process has been observed to contribute significantly to turbulent skin friction drag, suggesting that turbulent flow control techniques would benefit by seeking to disrupt it. One such technique is to manipulate the flow in such a way that results in the turbulence statistics of the different velocity components being shifted relative to each other in the wall normal direction. This may be achieved with complex geometrical structures, such as riblets, or with the use of non-conventional boundary conditions in numerical simulations, such as surface slip. Another technique, know as transpiration, counteracts velocity fluctuations near the wall by flow injection and suction at the wall itself, and can also result in a relative shift in the turbulence statistics. The primary aim of this project will be to simulate, understand and model the combined effect of surface slip and transpiration on near-wall turbulence by using direct numerical simulations (DNS). It might then be possible to identify an optimum combination of streamwise slip, spanwise slip and wall-normal transpiration for drag reduction that could later be used to aid in the design of novel control techniques.

壁面附近的湍流运动主要由两个关键相干结构（准流向涡和条纹）之间的相互作用驱动的准循环、自维持过程控制。已经观察到这个过程对湍流表面摩擦阻力有显著的贡献，这表明湍流控制技术将通过寻求破坏它而受益。其中一种技术是以这样一种方式操纵流动，即导致不同速度分量的湍流统计数据在壁法线方向上相对于彼此偏移。这可以通过复杂的几何结构（例如肋）或在数值模拟中使用非常规边界条件（例如表面滑移）来实现。另一种技术，称为蒸发，通过在壁本身处的流动注入和抽吸来抵消壁附近的速度波动，并且还可以导致湍流统计的相对偏移。该项目的主要目的是通过直接数值模拟（DNS）来模拟、理解和模拟表面滑移和蒸腾对近壁湍流的综合影响。这样就有可能确定出一种最佳的组合，即流向滑移、展向滑移和壁面法向蒸发的组合，以减少阻力，这种组合以后可用来帮助设计新的控制技术。