XU Hui： Target to reduce friction drag by roughness elements: Doable or Not?
报告人：XU Hui 研究员
工作单位：Imperial College London
Shanghai Jiao Tong University
Dr. Hui Xu is a Rolls-Royce researcher in the Department of Aeronautics and a research fellow in the Department of Mathematics at Imperial College London. His research interests span applied/computational mathematics and fluid mechanics. Much of his work has been on hydrodynamic instability, laminar-turbulent transition, aerodynamics /aeroacoustics, turbulence, kinetic theory based modelling/method, numerical analysis and computational methods. Dr. Hui Xu is currently working on broadband noise modelling and prediction, receptivity and instability of the boundary-layer transition stages and addressing the influences of free stream disturbance, wavy wall, surface imperfections, blowing and suction, external acoustic waves on instability of a boundary layer. He is also working on high-precision spectral/hp element method and applications. His researches are/were mainly funded by EPSRC, Rolls-Royce, Airbus, Bombardier McLaren, Renault and so on. He is working and collaborating with world-leading experts in the corresponding research fields. His research papers were mainly published in Journal of Fluid Mechanics, SIAM Journal on Scientific Computing, Journal of Computational Physics, Journal of Scientific Computing and so on.
Drag is the force by which a fluid resists the relative motion of a solid. The fluid can be external or internal to the wall boundaries which can be rigid or compliant. Flow control aims at minimising the drag force. In this talk, we will discuss about the challenging of deploying flow control strategies to achieve friction drag reduction for wall-bounded flowsand how to investigate the potential problems in validating the strategies precisely. Generally, the drag consists of three categories: profile drag, induced drag and wave drag. Here, we will not discuss induced drag and wave drag since they are respectively related to vorticity and supersonic flows. The talk will be focused on the skin friction drag which is categized into the profile drag and related to two kinds of strategies: laminar flow control and turbulent drag reduction. These two strategies are clearly proposed for two kinds of flows: laminar and turbulent flows. We either need to delay laminar-turbulent transition or enhance turbulence.