Key structure in laminar-turbulent transition of boundary layer with streaky structures

作     者：Joe Yoshikawa Yu Nishio Seiichiro Izawa Yu Fukunishi 

作者机构：Industrial Technology Institute Miyagi Prefectural Government Seikei University Tohoku University 

出 版 物：《Theoretical & Applied Mechanics Letters》 (力学快报（英文版）)

年 卷 期：2019年第9卷第1期

页      面：32-35,I0005页

核心收录：

学科分类：08[工学] 0831[工学-生物医学工程（可授工学、理学、医学学位）] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 0707[理学-海洋科学] 0815[工学-水利工程] 0805[工学-材料科学与工程（可授工学、理学学位）] 0813[工学-建筑学] 0824[工学-船舶与海洋工程] 0802[工学-机械工程] 0836[工学-生物工程] 0814[工学-土木工程] 0825[工学-航空宇航科学与技术] 0701[理学-数学] 0801[工学-力学（可授工学、理学学位）] 0702[理学-物理学] 

主　　题：Turbulent onset Key vortical structure Laminar-turbulent transition Boundary layer Streaky structures Short duration jet Numerical simulation 

摘      要：A numerical simulation is performed to find out a key vortical structure in the laminar-turbulent transition. A low-speed streak is generated inside a laminar boundary layer using an isolated cuboid roughness, aimed at providing an environment unstable to outer disturbances. Then, a short duration jet is issued into the boundary layer. When the jet velocity is low, some vortices appear in the boundary layer, but the transition of the boundary layer does not take ***, when the jet velocity exceeds a certain threshold, two vortices newly appear above the elongated legs of a V-shaped vortex and only one of them is stretched and survives. After that,vortices are generated one after another around the survived one. By comparing the decayed and the survived vortices, it is found that the difference in their heights is the key characteristic which leads to the transition.