Investigation of Turbulent Flow Separation and the Development of Flow Control Strategies for Bluff Bodies in Ground Proximity

钝体（砖块或某些道路车辆等四方形物体）的流动分离和空气动力学在许多工业应用中都遇到过。流动分离的后果包括显著的压力波动，这会导致阻力、结构振动、噪声等不良影响，并显著降低工程系统的效率和性能。众所周知，以高速公路为例，超过50%的燃料用于克服公路车辆的空气动力学阻力。由于上述原因，钝体空气动力学几十年来一直是一个研究热点。然而，对于复杂的三维钝体，一些基本问题尚未完全解决：如何准确地预测三维钝体上的阻力？提出的研究有三个短期目标：1)详细描述一些接近地面的三维钝体的平均和波动流结构；ii)开发对三维钝体有效的先进流动控制策略，以及用于量化它们的机械参数；iii)建立精确的数值模型，以充分捕捉钝体上的完整气动现象。为了满足短期目标，将构造各种三维钝体。然后将使用粒子图像测速、热线、压力传感器和力传感器在风洞和水洞的钝体周围进行速度、压力和力测量。此外，数值技术将用于这些研究使用开放源代码的数值代码。预计在未来5年内，将有16名HQP（3名博士，3名硕士，10名本科生）接受训练，进行详细的实验和数值模拟，使他们对钝体空气动力学有全面的物理理解。预计该研究计划的成功完成将为阐明我们对古老的基本问题的物理理解提供新的见解。这可以导致开发具有成本效益的流量控制装置，以提高工程系统的效率。它还将有助于减少加拿大的碳足迹及其对气候的影响。此外，HQP将培养在学术界或对加拿大具有社会经济重要性的不同行业就业的有用技能。

Flow separation and aerodynamics of bluff bodies (objects with boxy shapes like bricks or some road vehicles) are encountered in many industrial applications. The consequences of flow separation include significant pressure fluctuations that cause undesirable effects such as drag, structural vibration, noise and significant reductions in efficiency and performance of engineering systems. It is well-known that at highway speeds, for example, more than 50% of the fuel is used to overcome aerodynamic drag on road vehicles. For the above reasons, bluff body aerodynamics has been a subject of intensive research interests for many decades. However, for complex three-dimensional (3D) bluff bodies, some fundamental questions are not fully resolved: how do we accurately predict the drag on a 3D bluff body? The proposed research has three short-term objectives: i) characterize in detail the mean and fluctuating flow structures of a number of 3D bluff bodies in ground proximity; ii) develop advanced flow control strategies that are effective for 3D bluff bodies, and mechanistic parameters for quantifying them; and iii) develop accurate numerical models for fully capturing the complete aerodynamic phenomena on the bluff bodies. In order to meet the short-term objectives, a variety of 3D bluff bodies will be constructed. Velocity, pressure, and force measurements will then be conducted around the bluff bodies in wind and water tunnels using particle image velocimetry, hotwire, pressure sensors, and force sensors. In addition, numerical techniques will be employed for these studies using open source numerical codes. It is expected that over the next 5 years, 16 HQP (3 PhD, 3 MASc, and 10 undergraduate students) will be trained to perform detailed experiments and numerical simulations to enable them to gain a thorough physical understanding of bluff body aerodynamics. It is anticipated that a successful completion of the research program will provide new insight to illuminate our physical understanding of age-old fundamental questions. This can lead to the development of cost-effective flow control devices to improve the efficiency of engineering systems. It will also help reduce Canada's carbon footprint and its impacts on our climate. Additionally, HQP will develop useful skills for employment in academia or diverse industries of socio-economic importance to Canada.