报告主题：Settling and collision of ice crystals in turbulent flows

报告时间：7月23日（周二）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：

As an essential component of the Earth atmosphere, clouds are crucial for the climate. So far, a precise understanding of their properties has remained elusive, which leads to major uncertainties in determining quantitatively the impact of clouds on the climate. One of the unanswered questions concerns the rate of precipitation formation. Here, I will present numerical results, based on the simulation of the motion of ice crystals in turbulent flows, on the aggregation of ice crystals. This process, induced by the turbulent motion in clouds, is responsible for the formation of hail particles in thunderstorm clouds (cumulonimbus).  Our study allows us to discuss semi-quantitatively the physical mechanisms involved, which may be useful in improving the current cloud models.

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.