力学系与湍流国家重点实验室学术报告1.22（报告人：窦华书）
发布时间: 2010-01-18 03:24:00
SEMINAR SERIES
北京大学工学院 ![]()
力学与空天技术系
力学与空天技术系 湍流与复杂系统国家重点实验室
题目：Parallel Direct Numerical Simulation of Turbulent Transition Using 3D Navier-Stokes Equations
报告人 Hua-Shu Dou (窦华书)
Temasek Laboratories, National University of Singapore
报告内容摘要：
The energy gradient theory has been proposed to study the flow instability and turbulent transition in my previous researches. It was shown that the transition of a smooth laminar flow to turbulence flow depends on the magnitude of the Reynolds number and the amplitude of the imposed disturbance. This result obtains excellent agreement with the experiments. Following this theory, it is found that turbulent transition may be implemented by the singularity of the energy gradient function. Then, based on the proposed theory, two criteria for turbulent transition were proposed. (1) For pressure driving flows, the necessary and sufficient conditions for turbulent transition is the existence of an inflection point on the velocity profile. (2) For shear driving flows, the necessary and sufficient conditions for turbulent transition is the existence of a zero shear stress point on the velocity profile. For (1), it has been confirmed by experimental data in literature. For (2), in order to confirm this criterion, direct numerical simulation (DNS) of full Navier-Stokes equations is carried out for plane Couette flow.
The governing equations are the full 3D unsteady Navier-Stokes equations. The numerical method is the Fractional step method, in which the fully implicit method and second order backward temporal scheme is used; the finite volume method with second order central difference scheme is used for space discretization. In numerical treatment, geometric multigrid method and parallel computing with domain decomposition are employed. For plane Couette flow, the results shows that the critical Reynolds number (minimum Re) for turbulent transition is about 375, which is in agreement with the simulations and experiments from others in literature. The results from DNS show that the proposed criterion of turbulent transition is correct. This is for the first time that a set of complete criteria for turbulent transition are proposed and also confirmed.
报告人简介：
Dr. Hua-Shu Dou received a PhD degree in Aerodynamics from Beijing University of Aeronautics and Astronautics in 1991. Then, he joined Tsinghua University as a postdoctoral fellow and lecturer, and was subsequently promoted to associate professor in Tsinghua University in 1993. From 1994 to 1996, he worked in Tohoku University (Japan) as research fellow and Hosei University (Japan) as guest professor. From 1996 to 2002, he worked in The University of Sydney, Australia. Since 2002, he works in the National University of Singapore (NUS). Now, he is a Research Scientist in Temasek Laboratories at NUS and hold adjunction teaching position in mechanical engineering at NUS. Dr. Dou’s researches focus on computational fluid dynamics (CFD), aerodynamics, flow instability and turbulent transition, combustion and detonation, multiphase flows as well as numerical methods. He has published 90 papers in various refereed international journals and conferences. He has been invited to international conferences, universities, and companies to give lectures. He was in the committees of several international conferences and served as Session Chairman for several international conferences. He is reviewer and also in Editorial Board of several international journals. He is a member of ASME and APS as well as a senior member of AIAA.
主持人：李存标 教授
时 间：1月22日（周五）下午3:00
地 点：力学楼434会议室
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