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

各种各样的湍流要么是在多孔表面上，要么是在具有表面多孔性的物体的尾迹中。进化、工程设计、制造限制和自然现象导致这些多孔表面的粗糙和可渗透边界（例如热交换器中的流动、森林和城市树冠、鸟类羽毛和河床）。多孔表面的渗透性和粗糙度改变了在其上形成的湍流边界层，从而改变了尾迹经过具有表面多孔性的物体。这完全取决于粗糙度或尾迹上的边界层外部流动与多孔介质内流场之间的相互作用。尽管具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，显然需要进行系统的基础研究，以了解流动机制和多孔基质性质、多孔介质内的流场以及流过它们的湍流结构之间的关系。在这个雄心勃勃的合作项目中，我们将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结合起来，以获得湍流边界层和尾流在可渗透粗糙表面上和过去的基本理解。这将用于开发一个完全验证的建模框架，可以预测湍流与现实多孔表面相互作用的空气动力学和空气声学。具体来说，我们将(1)使用高保真实验研究多孔表面上形成的壁面湍流的气动和气动声学特性；(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DNS和LES，以了解多孔介质内部流动和外部流动之间的相互作用；(3)利用实验和数值数据开发新的模型来表示其他低保真度模拟中多孔表面内外流动之间的相互作用；(4)利用LES中的新模型来预测空气动力学和空气声学；(5)在大雷诺数范围内对流过和经过可渗透粗糙表面的空气动力学和空气声学进行测量，以进一步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研究不同现实多孔表面在流动/噪声控制中的效用。

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.