Seminar - Construction and evolution of vortex-surface fields in transitional flows by Dr. Yue Yang
日期：2017 年 02 月 17 日 ( 星期五)
Time：4:00 pm – 5:00 pm
We apply the vortex-surface field (VSF), a novel Lagrangian-based structure-identification method, to the DNS database of laminar-turbulent transitional flows for investigating the transition mechanism. The VSF, a smooth three-dimensional scalar field, is constructed from a vorticity field based on the constraint that the inner product of the vorticity and VSF scalar gradient is vanishing. The isosurface of the VSF is a vortex surface consisting of vortex lines. The VSF has been applied successfully to several transitional flows with simple initial conditions, including highly symmetric flows and transitional wall flows, to display the continuous temporal evolution of vortical structures. The evolution of VSFs can characterize stretching, rolling-up, twisting, and reconnection of vortex surfaces to elucidate the scale cascade and the rapid increase of wall friction in transitional flows from a Lagrangian view.
Yue Yang received double BE degrees in Thermal Engineering and Computer Science from Zhejiang University in 2004, MS degree in Fluid mechanics from Institute of Mechanics, Chinese Academy of Sciences in 2007, and PhD degree in Aeronautics from California Institute of Technology in 2011. Yang received the Richard Bruce Chapman Memorial Award for distinguished research in Hydrodynamics from Caltech, and the Combustion Energy Research Fellowship for postdoc research from CEFRC at Princeton University in 2011. Yang joined the Department of Mechanics and Engineering Science in College of Engineering at Peking University in 2013. His current research interests include modeling and numerical simulation of turbulence, turbulent combustion, and vortex dynamics. Yang received the “National Thousand Young Talents Plan” award and the “Qiu Shi Outstanding Young Scholar Award” in 2014, and the “Exellent Young Researcher” award from NSFC in 2015.