中文摘要：

本文采用直接数值模拟方法（DNS）研究了单相槽道流动问题.采用联合密度函数对近壁面区域内脉动速度分量进行了象限分析,同时,对脉动速度进行了概率密度分析及频谱分析,从而对近壁区域内流动的概率事件,速度概率分布及不同频率的涡对速度场的影响有了清晰的认识。研究发现,方向性事件主要集中在对数层以下,低频涡对于流向和法向脉动速度的贡献随着法向高度增加而增大,并且在近壁面上展向速度的脉动在对数层以及黏性底层存在较大脉动强度。

英文摘要：

A direct numerical simulation of a turbulent channel flow has been carried out.The main focus of the present work is on the statistical behavior of the velocity fluctuation components in near-wall region of the channel flow.Turbulence statistics are obtained via probability density functions（PDF）,joint probability density functions（JPDF） and energy spectrum analysis methods.It is found that the ejection and sweep motions mainly exist below the logarithmic region.The effects of the vortex with low frequency on the streamwise and wall-normal velocity fluctuations increase with the wall-normal distance,and the spanwise velocity fluctuations in the viscous sublayer and logarithmic regions are higher than that in other regions.