中文摘要：

基于边界层转捩后阶段的高精度直接数值模拟结果,发现流向条纹结构的低速条纹的演化过程中存在不连续现象,以及随高速条纹的发展会出现称之为＂高速斑＂的新特性.通过详细剖析边界层转捩过程中的复杂涡系结构以及上喷下扫流动现象,证实流向高低速条纹新特性与流场涡系结构的演化过程紧密相关.

英文摘要：

Based on detailed results of direct numerical simulation with high order accuracy and resolution at the late-stages of the transitional boundary layer, new properties are found, such as discontinuous event in the evolution of low-speed streamwise streaks and the appearance called high speed spots in the development of high-speed streamwise streaks. In the present paper, the complex vortex structures and the ejection-sweep phenomenon in the transition process of boundary layers are analyzed thoroughly, and the new properties of high-speed /low-speed streamwise streaks are confirmed to be closely relatcd to the evolution process of vortex structures in the flow-field.