Aerodynamics and aeroacoustics of turbulent flows over and past permeable rough surfaces

在多孔性表面上或在具有表面孔隙度的物体的尾流中，存在各种湍流。进化、工程设计、制造限制和自然现象导致这些多孔表面(如热交换器、森林和城市树冠、鸟类羽毛和河床中的流动)中的边界粗糙和可渗透。多孔表面的渗透性和粗糙度改变了在其上发展的湍流边界层，从而改变了通过具有表面孔隙度的物体的尾迹。这完全取决于粗糙度或尾迹上边界层中的外部流动与多孔介质内的流场之间的相互作用。尽管有广泛的影响和相关性，但显然缺乏基本的理解和将多孔介质的性质与外部流动特征联系起来的标度定律。这表明，显然有必要进行一项系统的基础研究，旨在了解多孔基质的流动机制和特性之间的关系，多孔介质内的流场和经过它们的湍流结构。在这个雄心勃勃的合作项目中，我们结合了南安普顿和布里斯托尔的实验专业知识与剑桥和南安普顿的计算和建模专业知识，以获得对可渗透粗糙表面上的湍流边界层和尾流的基本了解。这将被用来开发一个完全经过验证的建模框架，该框架可以预测与真实多孔表面相互作用的湍流的空气动力学和空气声学。具体地说，我们将(1)利用高保真实验研究在多孔表面上发展的壁面湍流的空气动力学和气动声学特性，(2)我们将使用新的内部工具对多孔表面上的流动进行详细的数值模拟和大涡模拟，以了解多孔介质内的内部流动和外部流动之间的相互作用，(3)使用实验和数值数据来开发新的模型，以在其他低保真模拟中表示多孔表面的内部和外部流动之间的相互作用，(4)利用大涡模拟中的新模型来预测空气动力学和空气声学；(5)在很大范围的雷诺数范围内对绕过和经过可渗透粗糙表面的流动进行空气动力学和空气声学测量，以加深我们的理解并验证我们的新模型。最终，这将使我们和我们的行业合作伙伴能够检查不同逼真的多孔表面在流动/噪音控制中的效用。

A variety of turbulent flows are either over porous surfaces or in the wake of bodies with surface porosity. Evolution, engineering design, manufacturing constraints and natural phenomena lead to rough and permeable boundaries in these porous surfaces (e.g. flow in heat exchangers, forest and urban canopies, bird feathers and river beds). The permeability and the roughness of a porous surface alters the turbulent boundary layer that develops over it and consequently the wake past an object with surface porosity. This entirely depends on the interaction between the external flow in the boundary layer over the roughness or the wake and the flow field within the porous media. Despite the wide-ranging impact and relevance, there is a clear lack of fundamental understanding and the scaling laws that relate the properties of porous media to the features of external flow. This points to the clear need for a systematic fundamental study aimed at understanding the flow mechanisms and the relationship between the properties of porous substrates, the flow field within the porous media and the structure of turbulent flow over and past them.In this ambitious collaborative project we combine the experimental expertise at Southampton and Bristol with the computational and modelling expertise at Cambridge and Southampton, to gain fundamental understanding of the turbulent boundary-layer and wake flow over and past permeable rough surfaces. This will be used to develop a fully-validated modelling framework that can predict the aerodynamics and aeroacoustics of turbulent flows interacting with realistic porous surfaces. Specifically, we will (1) examine the aerodynamic and aeroacoustic characteristics of wall-turbulence that develop over porous surfaces using high-fidelity experiments, (2) we will perform detailed DNS and LES of flow over porous surfaces using new in-house tools to understand the interaction between internal flow within the porous media and external flows, (3) use the experimental and numerical data to develop new models to represent the interaction between internal and external flow of porous surfaces in other lower fidelity simulations, (4) Utilise the new models in LES to predict the aerodynamics and aeroacoustics and (5) carry out measurements on the aerodynamics and aeroacoustics of flow over and past permeable rough surfaces over a large range of Reynolds numbers to further our understanding as well as to validate our new models. Ultimately, this will enable us and our industry partner to examine the utility of different realistic porous surfaces in flow/noise control.