The nature of near-wall convection velocity in turbulent channel flow  

作　　者：Yuhui Cao Jun Chen Zhensu She 

机构地区：[1]State Key Laboratory for Turbulence Research and ComplexSystem, College of Engineering, Peking University,Beijing 100871, China [2]Department of Mathematics,University of California at Los Angeles,Los Angeles, CA 90095, USA

出　　处：《Acta Mechanica Sinica》2008年第5期587-590,共4页力学学报（英文版）

基　　金：the National Natural Science Foundation of China(10572004 and 90716008)

摘　　要：A novel notion of turbulent structure the local cascade structure-is introduced to study the convection phenomenon in a turbulent channel flow. A space-time cross-correlation method is used to calculate the convection velocity. It is found that there are two characteristic convection speeds near the wall, one associated with small-scale streaks of a lower speed and another with streamwise vortices and hairpin vortices of a higher speed. The new concept of turbulent structure is powerful to illustrate the dominant role of coherent structures in the near-wall convection, and to reveal also the nature of the convection-the propagation of patterns of velocity fluctuations-which is scale-dependent.A novel notion of turbulent structure the local cascade structure-is introduced to study the convection phenomenon in a turbulent channel flow. A space-time cross-correlation method is used to calculate the convection velocity. It is found that there are two characteristic convection speeds near the wall, one associated with small-scale streaks of a lower speed and another with streamwise vortices and hairpin vortices of a higher speed. The new concept of turbulent structure is powerful to illustrate the dominant role of coherent structures in the near-wall convection, and to reveal also the nature of the convection-the propagation of patterns of velocity fluctuations-which is scale-dependent.

关 键 词：Turbulent structure CASCADE Structure classification CONVECTION Channel flow 

分 类 号：O35[理学—流体力学]