应航天航空学院Marie-Jean Thoraval教授邀请，荷兰屯特大学Varghese Mathai博士将来访我校并作学术报告。

报告人：Varghese Mathai博士

时间：2017年9月25日上午9:00-11:30

地点：航天航空学院教一楼第二会议室

报告题目：Dynamics of buoyant particles in turbulent flows

报告摘要：

Particle-suspensions in turbulent flows occur in nature and industry. In many situations, the particles have a density different from that of the carrier fluid. This density difference can affect their motion through flows, and offers potential for changing the drag as well as the transport of various quantities in multiphase flows. In this talk, we will discuss the use of particle-tracking techniques to study the dynamics of light (buoyant) particles in a homogeneous isotropic turbulent flows. We will begin with the acceleration dynamics of tiny buoyant particles (100 micron bubbles in water), with a very small Stokes number (St), where St signifies the particle’s response-time in the flow. We address the question: Can a small particle with a very small Stokes number be regarded a good tracer a flow? Our analysis shows that gravity can lead to modification of both vertical and horizontal acceleration statistics, and these occur despite the small size and minute St of these particles. We then address the motion of buoyant particles of finite-size (particle size is large compared to the smallest turbulent flow length-scales). For these particles, buoyancy is seen to produce interesting variability in motion. We will present the effect of changing the Galileo number on particle dynamics, and also touch upon some interesting effects of changing the particle’s moment of inertia. Some implications of these findings to dispersed particle-laden flows in ocean and atmosphere will also be discussed.

报告人简介：

Dr Varghese Mathai obtained his PhD in 2017 from the Physics of Fluids group at the University of Twente in the Netherlands. He is now a postdoctoral researcher in the same group. He has published papers in journals such as PRL, JFM, APL, and Exp. Fluids. His research interests include particle- and bubble-laden turbulent flows, wake-instabilities and vortex-induced-vibrations, and free surface flows. He will talk about the dynamics buoyant particles in turbulent flows.

http://pof.tnw.utwente.nl/people/profile/279