Experimental and Computational Turbulence in Engineering and Biological Flows

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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.**