Dynamic mode decomposition of hairpin vortices generated by a hemisphere protuberance  

作　　者：TANG ZhanQi JIANG Nan 

机构地区：[1]Department of Mechanics, Tianjin University, Tianjin 300072, China [2]Tianjin Key Laboratory of Modern Engineering Mechanics, Tianjin 300072, China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2012年第1期118-124,共7页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 10832001 and 10872145);the State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences

摘　　要：We present dynamic mode decomposition (DMD) for studying the hairpin vortices generated by hemisphere protuberance measured by two-dimensional (2D) time-resolved (TR) particle image velocimetry (PIV) in a water channel. The hairpins dynamic information is extracted by identifying their dominant frequencies and associated spatial structures. For this quasi-periodic data system, the resulting main Dynamic modes illustrate the different spatial structures associated with the wake vortex region and the near-wall region. By comparisons with proper orthogonal decomposition (POD), it can be concluded that the dynamic mode concentrates on a certain frequency component more effectively than the mode determined by POD. During the analysis, DMD has proven itself a robust and reliable algorithm to extract spatial-temporal coherent structures.We present dynamic mode decomposition （DMD） for studying the hairpin vortices generated by hemisphere protuberance measured by two-dimensional （2D） time-resolved （TR） particle image velocimetry （PIV） in a water channel. The hairpins dynamic information is extracted by identifying their dominant frequencies and associated spatial structures. For this quasi-periodic data system, the resulting main Dynamic modes illustrate the different spatial structures associated with the wake vortex region and the near-wall region. By comparisons with proper orthogonal decomposition （POD）, it can be concluded that the dynamic mode concentrates on a certain frequency component more effectively than the mode determined by POD. During the analysis, DMD has proven itself a robust and reliable algorithm to extract spatial-temporal coherent structures.

关 键 词：hairpin vortices hemisphere protuberance time-resolved particle image velocimetry dynamic mode decomposition proper orthogonal decomposition 

分 类 号：O35[理学—流体力学] TP311.13[理学—力学]