Experimental and Computational Turbulence in Engineering and Biological Flows

我的研究计划侧重于发现控制自由湍流(例如射流)和壁面受限流动(例如人体呼吸道内)中湍流结构的时空演变的基本原理和流动物理。*这项研究的目的是探索圆形湍流射流喷嘴附近区域，以发现其中遇到的湍流的程度和性质，并发现由于手术干预，阻塞的人体呼吸道中的压降和三维速度分布如何得到改善。*不受任何限制的喷气是常见的，也是至关重要的基本流动。在喷嘴区域，也就是射流开始的地方，远离射流起点的流动，称为远场，已经得到了广泛的研究。然而，一个连接近喷嘴区和远场的区域，流动物理丰富，对此知之甚少，但却起到了将初始入口条件输送到远场充分发展的湍流的作用。我和我的学生将应用直接数值模拟(DNS)，并使用我们独特的飞行热线设备来批判性地评估喷气式飞机偏离中心线的各向异性和非均匀区域。我们将在喷嘴附近引入被动控制环，以改变初始条件，从而增强混合并潜在地降低噪音，这是庞巴迪宇航公司感兴趣的。*正常的肺功能与向每个肺输送相同数量的空气有关。人体呼吸道气流受阻会导致呼吸困难和向肺部输送空气的不对称。阻塞性睡眠呼吸暂停(OSA)，通常与扁桃体/腺样体阻塞有关，可能需要手术纠正。正常的人类呼吸道在几何形状上很复杂，在整个呼吸道中产生复杂的流动模式，特别是在会厌和会厌外并进入气管，从而产生所谓的喉部喷射，其中包含自由喷射中的流动特征。阻塞性睡眠呼吸暂停综合征患者的几何结构异常复杂，可在气管内产生高度不对称的流动，从而导致流向肺部的不均匀分布。我们将使用域名系统和光学测量来探索手术前和手术后几何内部的流动。随着儿童越来越多地经历一系列与呼吸相关的健康问题，以及儿科呼吸道手术日益频繁，家长们面临着越来越多的担忧。临床医生需要更多地了解手术带来的流体动力学后果，这项研究将使这一点成为可能。*在DG期间，14名HQP将接受流体动力学高级研究技术培训，并将发展专业和沟通技能，为他们在学术界和行业的职业生涯做好准备。**

My research programme focuses on the discovery of the underlying principles and the flow physics that govern the spatial and temporal evolution of the structure of turbulence in both free turbulent flows (e.g. jets) and wall-bounded flows (e.g. inside the human airway).****The objectives of the research, each of which will employ both computer simulation and physical experiments, are to explore the near nozzle region of round turbulent jets to discover the extent and nature of the turbulence encountered therein and to discover how the pressure drop and the three dimensional velocity distributions in obstructed human airways are improved because of surgical intervention. ****Jets that are free of any confinement are common and a critically important fundamental flow. Flow in the nozzle area, where the jet starts, and well away from the start of the jet, called the far field, has been extensively studied. However, a region that bridges the near-nozzle area to the far field, which is rich in flow physics, is poorly understood and yet plays the role to transport initial inlet conditions through to fully developed turbulence in the far field. My students and I will apply direct numerical simulation (DNS) and use our unique flying hot wire facility to critically assess the anisotropic and non-homogeneous regions of a jet off its centreline. We will introduce passive control rings in the near nozzle region to alter the initial conditions thereby enhancing mixing and potentially reducing noise, which is of interest to Bombardier Aerospace.****Normal lung function is associated with delivery of the same amount of air to each lung. Obstructed airflow in the human airway gives rise to breathing difficulties and asymmetry in air delivery to the lungs. Obstructive sleep apnea (OSA), often associated with tonsil/adenoid blockage, may require surgery to rectify. Normal human airways are geometrically complex in shape and produce complicated flow patterns throughout the airway, particularly at and beyond the epiglottis and into the trachea to produce what is called the laryngeal jet, which contain flow features seen in free jets. The geometries in patients with OSA are exceptionally more complex and can produce highly asymmetric flow in the trachea that can lead to uneven distribution of flow to the lungs. We will use DNS and optical measurements to explore the flow inside pre- and post-operative geometries. Parents face growing concern as children are increasingly experiencing a range of breathing-related health issues and pediatric airway surgeries are being performed more often today.  Clinicians need to be more informed about the fluid dynamic consequences enabled by their surgeries, which this research will enable.****During this DG period, 14 HQP will be trained in advanced research techniques in fluid dynamics and will develop professional and communication skills to prepare them for careers in academe and industry.**