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Turbulent Flows Over Rough Surfaces

粗糙表面上的湍流

基本信息

批准号：
2486245
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：
2020
资助国家：
英国
起止时间：
2020 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-2486245
关键词：
Turbulent Flows Over Rough Surfaces

项目摘要

Reliable prediction of drag due to rough wall-bounded turbulent fluid flow remains a challenge in the energy and transportation industry. At the moment, the only accurate methods that predict drag are computationally expensive direct numerical simulations (DNS) or customised experimental rigs that implement the exact wall surface of interest. These solutions are not practical. The aim of my PhD is to investigate the underlying physics to lay the foundations for a predictive model. When the surface is only slightly rough, the velocity profiles away from the wall are smooth wall like and the drag increase can be calculated and modelled using the concept of virtual origins. However, when the wall is very rough, the velocity profiles are altered relative to the smooth-wall case. Therefore, the concept of virtual origins is not sufficient to model the drag increase. The time-averaged flow around an individual roughness element looks like the flow around a bluff body. The effect of this flow caused by the individual roughness elements propagates away from the wall. For my PhD, I want to investigate whether this time-averaged flow can be used to predict the change in the velocity profiles relative to the smooth-wall case. Not only would this change the way we think about rough wall-bounded flows, but it would also reduce the computation time of drag prediction significantly.

在能源和交通运输行业中，由于粗糙壁边界湍流流体流动引起的阻力的可靠预测仍然是一个挑战。目前，预测阻力的唯一准确方法是计算昂贵的直接数值模拟（DNS）或定制的实验装置，这些装置可以实现精确的壁面。这些解决办法并不实际。我的博士学位的目的是研究潜在的物理学，为预测模型奠定基础。当表面仅略微粗糙时，远离壁的速度分布是平滑的壁状，并且可以使用虚拟原点的概念来计算和建模阻力增加。然而，当壁面非常粗糙时，速度分布相对于光滑壁面情况发生改变。因此，虚拟原点的概念不足以模拟阻力增加。单个粗糙元周围的时间平均流看起来像海崖体周围的流。由各个粗糙度元素引起的这种流动的效果远离壁传播。对于我的博士学位，我想研究这个时间平均流是否可以用来预测相对于光滑壁情况的速度分布的变化。这不仅会改变我们对粗糙壁面边界流动的看法，而且会显著减少阻力预测的计算时间。