报告主题：Extremely large velocity gradients in turbulent flows

报告时间：7月17日（周三）下午2:00

报告地点：计算机楼A318室

报 告 人：Alain Pumir（CNRS, ENS-Lyon）

内容摘要：

Very turbulent flows are characterized by extremely intense velocity gradients, the more so as the flow is more turbulent (in quantitative terms, as the Reynolds number increases). These extreme events raise several important fundamental questions, including the very existence of regular solutions of the Navier-Stokes equations, which is one of the Clay problems in mathematics. Using a systematic numerical study of turbulent flows, at extremely high spatial and temporal resolution, I will show that the statistics of very intense velocity gradients obeys simple laws. I will also present our results concerning the structure of the regions of extreme velocity gradients. Finally, I will discuss the implications of the numerical results for flows in the limit of infinite Reynolds number.

报告人简介：

After studying at the Ecole Normale Supérieure in Paris, France, Alain Pumir went to Cornell University (USA) as a postdoctoral fellow (1984-1987). Back to France, he became CNRS junior scientist at the Ecole Normale Supérieure in Paris, before moving to Nice as a CNRS senior scientist (1993-2008). Since 2008, he is at the Ecole Normale Supérieure in Lyon, France. His work is devoted to fundamental problems in nonlinear and statistical physics, among others concerning turbulent flows, and biophysical problems. He actively collaborates with several institutions in different countries (Germany, USA, China). He received a Humboldt Award from Germany (2013), and became fellow of the American Physical Society (2014). Since 2018, he is External Scientific member of the Max-Planck Institute for Dynamics and Self-Organization in G?ttingen, Germany.