Secondary flow and streamwise vortices in three-dimensional staggered wavy-wall turbulence
The present paper simplifies the naturally formed dunes (riverbeds) as large-scale three-dimensional staggered wavy walls to investigate the features of the accompanying secondary flows and streamwise vortices via large-eddy simulation. A comparison between the swirling strength and the mean velocit...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Cambridge University Press
2023-01-01
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| Series: | Flow |
| Subjects: | |
| Online Access: | https://www.cambridge.org/core/product/identifier/S2633425923000132/type/journal_article |
| _version_ | 1797788128825573376 |
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| author | Enwei Zhang Zhan Wang Wangxia Wu Xiaoliang Wang Qingquan Liu |
| author_facet | Enwei Zhang Zhan Wang Wangxia Wu Xiaoliang Wang Qingquan Liu |
| author_sort | Enwei Zhang |
| collection | DOAJ |
| description | The present paper simplifies the naturally formed dunes (riverbeds) as large-scale three-dimensional staggered wavy walls to investigate the features of the accompanying secondary flows and streamwise vortices via large-eddy simulation. A comparison between the swirling strength and the mean velocities suggests where a secondary flow induces upwash or downwash motions. Moreover, we propose a pseudo-convex wall mechanism to interpret the directionality of the secondary flow. The centrifugal instability criterion is then used to reveal the generation of the streamwise vortices. Based on these analytical results, we found that the streamwise vortices are generated in the separation and reattachment points on both characteristic longitudinal–vertical and horizontal cross-sections, which is related to the curvature effect of the turbulent shear layer. Furthermore, the maximum Görtler number characterized by the ratio of centrifugal to viscous effects suggests that, for fixed ratio of spanwise- to streamwise-wavelength cases, the strongest centrifugal instability occurring on the longitudinal–vertical cross-section gradually dominates with the increases in amplitude. A similar trend for the cases with varied spanwise wavelength can also be found. It is also found that the streamwise vortices are generated more readily via transverse flow around the crest near the separation and reattachment points when the ratio of spanwise- to streamwise-wavelength equals 1. |
| first_indexed | 2024-03-13T01:32:15Z |
| format | Article |
| id | doaj.art-a17795c6d0ee417abb65fc5df4833e98 |
| institution | Directory Open Access Journal |
| issn | 2633-4259 |
| language | English |
| last_indexed | 2024-03-13T01:32:15Z |
| publishDate | 2023-01-01 |
| publisher | Cambridge University Press |
| record_format | Article |
| series | Flow |
| spelling | doaj.art-a17795c6d0ee417abb65fc5df4833e982023-07-04T07:33:21ZengCambridge University PressFlow2633-42592023-01-01310.1017/flo.2023.13Secondary flow and streamwise vortices in three-dimensional staggered wavy-wall turbulenceEnwei Zhang0https://orcid.org/0000-0002-0562-0837Zhan Wang1https://orcid.org/0000-0003-4393-2118Wangxia Wu2https://orcid.org/0000-0001-5548-8312Xiaoliang Wang3Qingquan Liu4https://orcid.org/0000-0002-4472-6626Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, PR ChinaInstitute of Mechanics, Chinese Academy of Sciences, Beijing 100190, PR ChinaSchool of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, PR ChinaSchool of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, PR ChinaSchool of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, PR ChinaThe present paper simplifies the naturally formed dunes (riverbeds) as large-scale three-dimensional staggered wavy walls to investigate the features of the accompanying secondary flows and streamwise vortices via large-eddy simulation. A comparison between the swirling strength and the mean velocities suggests where a secondary flow induces upwash or downwash motions. Moreover, we propose a pseudo-convex wall mechanism to interpret the directionality of the secondary flow. The centrifugal instability criterion is then used to reveal the generation of the streamwise vortices. Based on these analytical results, we found that the streamwise vortices are generated in the separation and reattachment points on both characteristic longitudinal–vertical and horizontal cross-sections, which is related to the curvature effect of the turbulent shear layer. Furthermore, the maximum Görtler number characterized by the ratio of centrifugal to viscous effects suggests that, for fixed ratio of spanwise- to streamwise-wavelength cases, the strongest centrifugal instability occurring on the longitudinal–vertical cross-section gradually dominates with the increases in amplitude. A similar trend for the cases with varied spanwise wavelength can also be found. It is also found that the streamwise vortices are generated more readily via transverse flow around the crest near the separation and reattachment points when the ratio of spanwise- to streamwise-wavelength equals 1.https://www.cambridge.org/core/product/identifier/S2633425923000132/type/journal_articleTopographic effects |
| spellingShingle | Enwei Zhang Zhan Wang Wangxia Wu Xiaoliang Wang Qingquan Liu Secondary flow and streamwise vortices in three-dimensional staggered wavy-wall turbulence Flow Topographic effects |
| title | Secondary flow and streamwise vortices in three-dimensional staggered wavy-wall turbulence |
| title_full | Secondary flow and streamwise vortices in three-dimensional staggered wavy-wall turbulence |
| title_fullStr | Secondary flow and streamwise vortices in three-dimensional staggered wavy-wall turbulence |
| title_full_unstemmed | Secondary flow and streamwise vortices in three-dimensional staggered wavy-wall turbulence |
| title_short | Secondary flow and streamwise vortices in three-dimensional staggered wavy-wall turbulence |
| title_sort | secondary flow and streamwise vortices in three dimensional staggered wavy wall turbulence |
| topic | Topographic effects |
| url | https://www.cambridge.org/core/product/identifier/S2633425923000132/type/journal_article |
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