（ 1、天津大学力学系，天津 300072； 2、天津市现代工程力学重点实验室，天津 300072； ）
（ Department of Mechanics, Tianjin University, Tianjin 300072；Tianjin Key Laboratory of Modern Engineering Mechanics, Tianjin 300072； ）
Abstract： At high level of environmental disturbance, bypass transition takes place in the boundary layer. Bypass transition of boundary layer under spanwise localized free-stream turbulence is a usual type of bypass transition, which is described as the following process in fluid mechanics. Firstly, low-frequency disturbances in free-stream turbulence penetrate into the boundary layer and induce streamwise streaks. Amplitude of the streaks grows significantly until it becomes saturated. Then secondary instability of streaky boundary layer occurs such that the flow becomes turbulent. The generation and nonlinear evolution of streaks until saturation have been studied in literature. In this paper, the secondary instability of streaky boundary layer is investigated. The instability analysis is carried out at different streamwise locations, and the results are taken into consideration in the whole space-time plane, such that convecting modes are found. Along the convecting modes, the growth of secondary instability can accumulate in stramwise direction. Due to comparison of the growth of each convecting mode, the following characters of secondary instability of bypass transition under spanwise localized free-stream turbulence are found. Firstly, the contribution of secondary instability to bypass transition is much more important than T-S waves. Secondly, the center strong streak plays the key role in secondary instability. Thirdly, the inner mode on center high-speed streak is the dominant one in secondary instability, while the sinuous outer mode on center low-speed streak plays a certain role.
Keywords： fluid mechanics; secondary instability; bypass transition; convecting mode; inner mode; outer mode
张永明. 展向局部自由流湍流下带条纹边界层的二次失稳分析[EB/OL].北京：中国科技论文在线 [2016-09-01].http://www.paper.edu.cn/releasepaper/content/201609-3.