槽道湍流的展向振荡电磁力壁面减阻

采用直接数值模拟方法,对槽道湍流的展向振荡电磁力的减阻效果和减阻机理进行了研究,讨论了电磁力强度和振荡频率对湍流猝发事件以及壁面减阻率的影响.结果表明,电磁力强度或振荡频率变化时,湍流猝发频率和猝发强度的变化趋势是相反的,所以存在最优参数使得减阻效果最好.等价壁面展向速度可以很好地描述电磁力强度和振荡频率的变化对减阻效果的综合效应。

Drag reduction in turbulent channel flow by spanwise oscillating Lorentz force

Direct numerical simulation (DNS) of a turbulent channel flow is carried out to investigate the effect and mechanism of using spanwise oscillating Lorentz force to reduce boundary layer friction.We discussed the influence of Lorentz force intensity St and oscillating frequency T⁺ on the drag reduction effect and turbulent burst events. The results suggest the varying tendencies with St or T⁺ of the frequency of the turbulent bursts events are opposite to the intensity of the turbulent bursts events,and there exists an optimal parameter to achieve the largest amount of drag reduction.The composite effect of St and T⁺ can be well described by the equivalent spanwise wall velocity W⁺.