中文摘要：

本文采用展向周期性布置圆柱形粗糙元的方式,直接数值模拟了平板表面流向条纹的增长过程。研究发现由于流向涡的＂lift-up＂效应,粗糙元下游区域出现高速条纹结构,而粗糙元的尾流对于条纹结构的初期形成有着重要影响。随着流动的不断发展,展向脉动速度分布有发展成为正弦曲线形式的趋势,而法向脉动速度峰值则呈先减小后增大的趋势。

英文摘要：

In order to investigate the growth of streamwise streaks in a flat plate,a direct numerical simulation was performed using a spanwise array of cylindrical roughness elements.A high speed streak is formed straight behind the element because of the ＂lift-up＂ effect of streamwise vortices and the wake of roughness element has a significant effect on the streaks structure early formation. The spanwise perturbation velocity profiles change into almost sinusoidal curves and the peak of disturbance at the wall-normal direction decreases firstly and then increases with the evolution of the flow.