展向周期振动的平板近壁湍流结构研究

Structure of near-wall turbulence due to spanwise wall oscillation in channel flow

通过直接数值模拟(DNS)对壁面作展向周期运动的槽道湍流进行研究,建立了槽道湍流数据库。通过改变振幅大小和振动周期,可以使壁面阻力明显减少。根据计算结果分析了减阻率和振动参数的关系。利用减阻后近壁湍流拟序结构的变化,研究了壁面展向周期振动减阻的内在机理,揭示了三种减阻过程中涡结构对近壁流体的上抛、下扫运动以及条带结构的影响规律。

A turbulent channel flow subjected to spanwise wall oscillation has been investigated by direct numerical simulation （DNS）. The database of turbulent channel flow has been produced by DNS. The drag can be reduced significantly by changing the amplitude and the period of the oscillation. The relation between the ratio of drag reduction and the control parameters is analyzed according to the results. An investigation into the mechanism of drag reduction has been carried out via analyzing the structure of near-wall turbulence. Three kinds of influence of vortex structures on the ejection,the sweep and the streak of near-wall turbulence are revealed.