CBET-EPSRC: Turbulent flows over multiscale heterogeneous surfaces

CBET-EPSRC：多尺度异质表面上的湍流

• 批准号: EP/P021476/1
• 负责人: Bharathram Ganapathisubramani
• 金额: $ 62.36万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 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=EP%2FP021476%2F1
• 关键词: CBET; EPSRC; Turbulent; flows; over

A turbulent boundary layer is formed when a fluid flows past a surface. This boundary layer is primarily responsible for the skin-friction drag incurred by the surface. In almost all engineering and environmental flow applications, these boundary layers are formed over non-smooth or rough surfaces where the roughness of the surface plays a significant role in setting the drag and its repercussions on the flow. And yet, we are unable to truly predict the influence of these rough surfaces on the flow. This is primarily because the topography of surface roughness is usually "multiscale" in nature that contains a wide variety of roughness length scales. More importantly, the variation in the range of roughness length scales and the distribution of the roughness features is "heterogeneous" across the surface. Examples include edges of forests or wind-farms, urban canopies, crop boundaries, river-beds, land-water interfaces, rivets on aircraft, ablated turbine blades, macro bio-fouled ship hulls etc. The turbulent boundary layers that evolve over such heterogeneous multiscale roughness experience non-uniform surface conditions and as a result exhibit properties that are different from flows that develop over homogeneous roughness. Consequently, current modelling and prediction strategies (such as the Moody diagram) that were developed for surfaces with homogeneous roughness can neither accurately predict nor offer insights into the complex physics of flow over heterogeneous multiscale surfaces. Therefore, considerable advancements and benefits would result across a whole range of sectors if we are able to predict the effects of multiscale surface heterogeneity on turbulent boundary layers.In this collaborative research, we aim to apply a systematic approach to characterize drag and mechanisms of momentum transfers in flows over heterogeneous multiscale surfaces. A series of physical experiments - to be performed at Southampton in the UK - and Large Eddy Simulations - to be carried out at Johns Hopkins in the US - will generate unprecedented data of flows over heterogeneous multiscale surfaces. Examining flows over such surfaces will develop our fundamental understanding of the coupling between the non-linearities in the turbulent flow and its relationship with the multiscale heterogeneity of the surface. This understanding will bring about a paradigm shift in how we understand and predict non-equilibrium turbulent wall-flows and the multiscale interactions that are responsible for its development. Synthesizing the new insights obtained from the data, we will develop new analytical models to predict the drag and properties of momentum transfer based only on available information about the surface topography. The ultimate aim is to develop truly predictive models for engineering and environmental flow applications.

当流体流过表面时，形成湍流边界层。这个边界层主要负责由表面引起的表面摩擦阻力。在几乎所有的工程和环境流动应用中，这些边界层形成于非光滑或粗糙表面上，其中表面的粗糙度在设置阻力及其对流动的影响方面起着重要作用。然而，我们无法真正预测这些粗糙表面对流动的影响。这主要是因为表面粗糙度的形貌通常是“多尺度”的性质，包含各种各样的粗糙度长度尺度。更重要的是，粗糙度长度尺度的范围和粗糙度特征的分布的变化在整个表面上是“不均匀的”。例子包括森林或风力发电场，城市树冠，作物边界，河床，陆地-水界面，飞机上的铆钉，烧蚀的涡轮机叶片，宏观生物污染船体等的湍流边界层，在这种异质多尺度粗糙度的经验，非均匀的表面条件，并因此表现出不同的属性，从均匀的粗糙度发展的流量。因此，目前的建模和预测策略（如穆迪图），开发的表面均匀粗糙度既不能准确地预测，也不能提供洞察复杂的物理流动的异质多尺度表面。因此，相当大的进步和利益，将导致在整个范围内的部门，如果我们能够预测的影响，多尺度表面的非均匀性湍流boundarylayers.In这项合作研究中，我们的目标是应用一个系统的方法来表征阻力和机制的动量传递的流动在非均匀多尺度表面。一系列物理实验（将在英国南安普顿进行）和大涡模拟（将在美国约翰·霍普金斯大学进行）将产生前所未有的异质多尺度表面流动数据。检查这些表面上的流动将发展我们对湍流中的非线性之间的耦合及其与表面的多尺度非均匀性的关系的基本理解。这种理解将带来一个范式的转变，我们如何理解和预测非平衡湍流壁流和多尺度相互作用，负责其发展。综合从数据中获得的新见解，我们将开发新的分析模型，仅根据有关表面形貌的可用信息来预测阻力和动量传递特性。最终目标是为工程和环境流量应用开发真正的预测模型。

项目成果

Turbulent Flow Over Large Roughness Elements: Effect of Frontal and Plan Solidity on Turbulence Statistics and Structure.

大粗糙度元素上的湍流：锋面和平面密实度对湍流统计和结构的影响。

• DOI: 10.1007/s10546-017-0317-3
• 发表时间: 2018
• 期刊: Boundary-layer meteorology
• 影响因子: 4.3
• 作者: Placidi M

PIV-based pressure estimation in the canopy of urban-like roughness

• DOI: 10.1007/s00348-020-2904-1
• 发表时间: 2020-02
• 期刊: Experiments in Fluids
• 影响因子: 2.4
• 作者: M. A. Ferreira;B. Ganapathisubramani

Turbulent Boundary Layers Over Multiscale Rough Patches

多尺度粗糙斑块上的湍流边界层

• DOI: 10.1007/s10546-019-00430-x
• 发表时间: 2019
• 期刊: Boundary-Layer Meteorology
• 影响因子: 4.3
• 作者: Vanderwel C

Scalar transport in flow past finite circular patches of tall roughness

• DOI: 10.1016/j.ijheatfluidflow.2023.109167
• 发表时间: 2023-08
• 期刊: International Journal of Heat and Fluid Flow
• 影响因子: 2.6
• 作者: D. Wangsawijaya;C. Nicolai;B. Ganapathisubramani

Effects of heterogeneous surface geometry on secondary flows in turbulent boundary layers

• DOI: 10.1017/jfm.2019.1014
• 发表时间: 2020-01
• 期刊: Journal of Fluid Mechanics
• 影响因子: 3.7
• 作者: T. Medjnoun;C. Vanderwel;B. Ganapathisubramani