中文摘要：

从近墙的 streamwise 旋涡的一个发卡旋涡的产生经由条纹的直接数字的模拟(DNS ) 被学习在在 \(Re_\tau =400\) 的最小的隧道流动的短暂生长。条纹侧面被有条件地在一样的雷纳兹数字平均充分发达的狂暴的隧道流动的 DNS 数据获得。近墙的 streamwise 旋涡被开始受到 spanwise 速度的蜿蜒的不安的条纹的短暂生长生产。发卡旋涡的拱门头首先从更强壮的 streamwise 旋涡的下游的结束成长然后在他们的重叠区域与更弱的、签名反面的 streamwise 旋涡连接，这被显示出，形成完全的单个发卡结构。沿着旋涡线的涡度运输显示力量增加和拱门头的空间扩大由于分别地拉长并且转弯涡度向量。发卡包能进一步从跟随父母后代过程的产生单个发卡旋涡被生产。

英文摘要：

The generation of a hairpin vortex from near-wall streamwise vortices is studied via the direct numerical simulation（DNS） of the streak transient growth in the minimal channel flow at Re_τ- 400.The streak profile is obtained by conditionally averaging the DNS data of the fully developed turbulent channel flow at the same Reynolds number.The near-wall streamwise vortices are produced by the transient growth of the streak which is initially subjected to the sinuous perturbation of the spanwise velocity.It is shown that the arch head of the hairpin vortex first grows from the downstream end of the stronger streamwise vortex and then connects with the weaker,opposite-signed streamwise vortex in their overlap region,forming a complete individual hairpin structure.The vorticity transport along the vortex lines indicates that the strength increase and the spatial expansion of the arch head are due to the stretching and the turning of the vorticity vector,respectively.The hairpin packets could be further produced from the generated individual hairpin vortex following the parent-offspring process.