A new kind of hairpin-like vortical structure induced by cross-interaction of sinuous streaks in turbulent channel  

作　　者：Jian Li Gang Dong Hui Zhang Zhengshou Chen Zhaode Zhang 李健;董刚;张辉;陈正寿;张兆德(School of Naval Architecture and Mechanical-electrical Engineering,Zhejiang Ocean University,Zhoushan 316022,China;National Key Laboratory of Transient Physics,Nanjing University of Science and Technology,Nanjing 210094,China;Key Laboratory of Offshore Engineering Technology of Zhejiang Province,Zhoushan 316022,China)

机构地区：[1]l School of Naval Architecture and Mechanical-electrical Engineering,Zhejiang Ocean University,Zhoushan 316022,China [2]National Key Laboratory of Transient Physics,Nanjing University of Science and Technology,Nanjing 210094,China [3]Key Laboratory of Offshore Engineering Technology of Zhejiang Province,Zhoushan 316022,China

出　　处：《Chinese Physics B》2018年第8期331-340,共10页中国物理B（英文版）

基　　金：Project supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LQ18A020002);the National Natural Science Foundation of China(Grant No.41776105);the Foundation of the Educational Committee of Zhejiang Province,China(Grant No.Y201737053)

摘　　要：This work is motivated by previous experimental and numerical studies which reveal that the hairpin vortex could be formed by the interaction between spanwise adjacent low-speed streaks. To prove that such an interaction mechanism is still applicable in the normal direction, two sinuous low-speed streaks with the same streamwise phase are set to be in the upper half and bottom half of a small size channel, respectively, and their evolution and interaction are investigated by direct numerical simulation. A new kind of hairpin-like vortical structure, distributed in the normal direction and straddled across both halves of the channel, is found during the cross-interaction process of the low-speed streaks. The influence of such a normal-distributed hairpin-like vortex （NHV） on the turbulent statistical regularity is also revealed. It is observed that the NHV can lead to a sudden surge of wall skin friction, but the value of the normal velocity as well as the streamwise and spanwise vorticity sharply decrease to zero in the center of the channel.This work is motivated by previous experimental and numerical studies which reveal that the hairpin vortex could be formed by the interaction between spanwise adjacent low-speed streaks. To prove that such an interaction mechanism is still applicable in the normal direction, two sinuous low-speed streaks with the same streamwise phase are set to be in the upper half and bottom half of a small size channel, respectively, and their evolution and interaction are investigated by direct numerical simulation. A new kind of hairpin-like vortical structure, distributed in the normal direction and straddled across both halves of the channel, is found during the cross-interaction process of the low-speed streaks. The influence of such a normal-distributed hairpin-like vortex （NHV） on the turbulent statistical regularity is also revealed. It is observed that the NHV can lead to a sudden surge of wall skin friction, but the value of the normal velocity as well as the streamwise and spanwise vorticity sharply decrease to zero in the center of the channel.

关 键 词：low-speed streaks hairpin vortex channel flow direct numerical simulation 

分 类 号：O4[理学—物理]