报告人：杨越（Peking University）
时 间：2014年10月28日（周二）12:30―13:30
地 点：工学院1号楼210会议室
主持人：康炜 特聘研究员

报告简介：
We present a Lagrangian study on the evolution of turbulent coherent structures in the laminar-turbulent transition in incompressible channel flow and weakly compressible boundary layer flow. Based on the Eulerian velocity field from the direct numerical simulation, a backward-particle-tracking method is used to solve the Lagrangian scalar transport equation, and then Lagrangian material surfaces are extracted as isosurfaces of the Lagrangian scalar. As an approximation of the Helmholtz vorticity theorem, a Lagrangian surface, which is initially a vortex surface composed of vortex lines, can be approximately considered as a vortex surface before significant vortex reconnections in temporal evolution. By tracking the evolution of Lagrangian material surfaces in the early transitional phase, the dynamics of coherent structures, e.g., hairpin vortices, can be studied in a Lagrangian framework. The statistical geometry of Lagrangian structures can then be quantified by scalar gradients and the multi-scale, multi-directional geometric analysis.

报告人介绍：
杨越，2004年浙江大学获热能动力工程专业与计算机科学双学士学位，2007年中国科学院力学所获流体力学专业硕士学位，2011年美国加州理工学院获航空专业博士学位。博士后期间获美国普林斯顿大学燃烧能源中心Combustion Energy Research Fellowship奖励资助，于康奈尔大学、Sandia国家实验室开展湍流燃烧数值模拟研究工作。2013年加入北京大学工学院，现任力学与工程科学系特聘研究员。目前研究方向包括湍流理论与数值模拟、湍流燃烧、涡动力学。