摘要
展向旋转平板Couette湍流(Spanwise rotating plane Couette flow,RPCF)是旋转壁湍流的标模问题之一,在过去的几十年里,被广泛用来研究旋转对壁湍流的统计和流动结构的影响。近些年,作者及其合作者就该问题开展了一系列直接数值模拟研究工作。该研究不仅发现了旋转在低旋转数和高旋转数时对流动结构和统计的不同影响,还首次在RPCF中发现了多湍流态现象:即在相同的控制参数下,流动可以处在两种不同的湍流态上,这两种不同的湍流态的流动结构和湍流统计差别显著。还发现该多态现象可以在很大的旋转数范围里存在。进一步分析大尺度二次流在不同态的能量传输中的作用,发现在二次流较弱的流态下,二次流起的作用相对较小,能量很大一部分直接从平均流传到剩余场;而当二次流较强时,二次流起到一个能量传输纽带作用。该分析也从侧面验证了大尺度结构在多态现象中占据重要地位的猜想。
As one of the canonical flow problems in wall-bounded turbulence with system rotation,spanwise rotating plane Couette flow(RPCF)has been studied a lot in the past decades to investigate the rotation effect on the turbulent statistics and flow structures.Recently,the author and his collaborators had performed a series of direct numerical simulations on this flow problem.The results showed that the strong rotation and weak rotation have different impact on the flow structures and turbulent statistics.Furthermore,they have found that multiple states do exist in RPCF.That is,at the same control parameters(Reynolds number and Rotation number),the flow could be at two different flow states,and the flow structures and turbulent statistics at these two states show obvious differences.Their simulation results also showed that the multiple states could exist over a wide rotation number range.Further analysis on the role of secondary flows showed that the secondary flows play different roles in the energy transfer at different states.If the secondary flows are very strong,most of the energy from the mean field will first transfer to the secondary flow and then transfer to the residual field,and the secondary flows acts as a kinetic energy bridge that transfers the energy from the mean field to the residual field.On the other hand,if the secondary flows are not strong enough,most of the kinetic energy will transfer from the mean field to the residual field directly.The present results support the previous conjecture that the large-scale flow structures(the secondary flows)play a very critical role at the multiple states.
作者
夏振华
XIA Zhenhua(Department of Engineering Mechanics,Zhejiang University,Hangzhou 310027,China)
出处
《空气动力学学报》
CSCD
北大核心
2020年第1期118-127,共10页
Acta Aerodynamica Sinica
基金
国家自然科学基金(11822208,11772297)
