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    韩国首尔大学机械与航空系HAECHEON CHOI教授学术讲座
    点击量: 录入时间:2018-10-09

     

     

    应机械结构强度与振动国家重点实验室、智能飞行器流固耦合力学与仿生技术学科创新引智和陕西省先进飞行器服役环境与控制重点实验室邀请,韩国科学院、工程院两院院士、JFM副主编、韩国首尔大学HAECHEON CHOI教授,将于近期访问西安交通大学航天航空学院并作学术报告。欢迎大家参加。

      间: 20181015日下午14:30-16:00

      点: 航天航空学院教一楼第三会议室

    报告人Prof.Haecheon Choi

    报告题目: Machine-learning based turbulence prediction and control

    摘要:An accurate but efficient prediction of turbulence is one of the ultimate goals in fluid mechanics society. To predict turbulence, it is important to know the correlations among two or more flow variables at different spatial locations. Understanding these correlations from the Navier-Stokes equations is quite difficult and sometimes impossible. In this talk, we apply machine learning (ML) tools (from linear regression to deep learning) to predict turbulence for two different problems: one is to model subgrid-scale (SGS) stresses for large eddy simulation, and the other is to predict near-wall turbulence based on wall variable sensing. For SGS modeling, we first train the ML model for homogeneous isotropic turbulence to predict SGS stresses from resolved flow variables. Results show that the ML model outperforms traditional models such as the Smagorinsky model for the predictions of SGS dissipation, energy spectrum, and vortical structures. We also train ML models for turbulent channel flow to predict near-wall flow based on wall variable sensing. The near-wall flows predicted are very similar to real ones. How to visualize (or understand) the ‘black box’ in the process of ML is also discussed in this talk. Finally, turbulence control based on wall variable sensing is performed for skin friction reduction in channel flow, providing a significant amount of drag reduction.

     

    报告人简介:

    Professor Choi received his BS and MS degrees from Seoul National University in 1985 and 1987, respectively, and his Ph.D degree from Stanford University in 1992. He has been a professor at Seoul National University since 1993. He is interested in turbulence, flow control, CFD, and bio-mimetic engineering. He is a fellow of American Physical Society, and a member of The National Academy of Engineering of Korea and The Korean Academy of Science and Technology. He is an Associate Editor of Journal of Fluid Mechanics, and editorial board member for Flow, Turbulence and Combustion, Int. J. Heat and Fluid Flow, and Int. J. Multiphase Flow.

     

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