Wavelet Coherency Structure in Open Channel Flow
Many studies based on single-point measurement data have demonstrated the impressive ability of wavelet coherency analysis to catch the coherent structures in the wall-bounded flows; however, the question of how the events found by the wavelet coherency analysis relate to the features of the coheren...
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doaj-5922f9e9b7a84fd6b0ef5a7122a882812020-11-25T01:56:32ZengMDPI AGWater2073-44412019-08-01118166410.3390/w11081664w11081664Wavelet Coherency Structure in Open Channel FlowKebing Chen0Yifan Zhang1Qiang Zhong2College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, ChinaCollege of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, ChinaCollege of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, ChinaMany studies based on single-point measurement data have demonstrated the impressive ability of wavelet coherency analysis to catch the coherent structures in the wall-bounded flows; however, the question of how the events found by the wavelet coherency analysis relate to the features of the coherent structures remains open. Time series of velocity fields in <i>x</i>−<i>y</i> plane of the steady open channel flow was obtained from a time-resolved particle imaging velocimetry system. The local wavelet spectrum found shows that one of the main energetic scales in open channel flows is 3<i>h</i> motions. The wavelet coherent coefficients of <i>u</i> and <i>v</i> series from the same measurement points successfully detected the occurrence and the scale of these 3<i>h</i> motions, and the phase angle indicates their inside velocity structure is organized by the Q2 and Q4 events. The wavelet coherency analysis between different measurement points further reveals the incline feature of the 3<i>h</i> scale motions. All the features of this 3<i>h</i> motion found by the wavelet coherency analysis coincide well with the flow field that is created by the passing of hairpin packets.https://www.mdpi.com/2073-4441/11/8/1664wavelet coherencyTaylor’s frozen turbulence hypothesisscalehairpin vortex packetopen channel flow |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Kebing Chen Yifan Zhang Qiang Zhong |
spellingShingle |
Kebing Chen Yifan Zhang Qiang Zhong Wavelet Coherency Structure in Open Channel Flow Water wavelet coherency Taylor’s frozen turbulence hypothesis scale hairpin vortex packet open channel flow |
author_facet |
Kebing Chen Yifan Zhang Qiang Zhong |
author_sort |
Kebing Chen |
title |
Wavelet Coherency Structure in Open Channel Flow |
title_short |
Wavelet Coherency Structure in Open Channel Flow |
title_full |
Wavelet Coherency Structure in Open Channel Flow |
title_fullStr |
Wavelet Coherency Structure in Open Channel Flow |
title_full_unstemmed |
Wavelet Coherency Structure in Open Channel Flow |
title_sort |
wavelet coherency structure in open channel flow |
publisher |
MDPI AG |
series |
Water |
issn |
2073-4441 |
publishDate |
2019-08-01 |
description |
Many studies based on single-point measurement data have demonstrated the impressive ability of wavelet coherency analysis to catch the coherent structures in the wall-bounded flows; however, the question of how the events found by the wavelet coherency analysis relate to the features of the coherent structures remains open. Time series of velocity fields in <i>x</i>−<i>y</i> plane of the steady open channel flow was obtained from a time-resolved particle imaging velocimetry system. The local wavelet spectrum found shows that one of the main energetic scales in open channel flows is 3<i>h</i> motions. The wavelet coherent coefficients of <i>u</i> and <i>v</i> series from the same measurement points successfully detected the occurrence and the scale of these 3<i>h</i> motions, and the phase angle indicates their inside velocity structure is organized by the Q2 and Q4 events. The wavelet coherency analysis between different measurement points further reveals the incline feature of the 3<i>h</i> scale motions. All the features of this 3<i>h</i> motion found by the wavelet coherency analysis coincide well with the flow field that is created by the passing of hairpin packets. |
topic |
wavelet coherency Taylor’s frozen turbulence hypothesis scale hairpin vortex packet open channel flow |
url |
https://www.mdpi.com/2073-4441/11/8/1664 |
work_keys_str_mv |
AT kebingchen waveletcoherencystructureinopenchannelflow AT yifanzhang waveletcoherencystructureinopenchannelflow AT qiangzhong waveletcoherencystructureinopenchannelflow |
_version_ |
1724979490202845184 |