Chaotic and time-periodic edge states in square duct flow.
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| Title: | Chaotic and time-periodic edge states in square duct flow. |
|---|---|
| Authors: | Weyrauch, Markus1 (AUTHOR) markus.scherer@kit.edu, Uhlmann, Markus1,2 (AUTHOR), Kawahara, Genta1,2 (AUTHOR) |
| Source: | Journal of Fluid Mechanics. 10/24/2025, Vol. 1021, p1-35. 35p. |
| Subjects: | Turbulence, Turbulent flow, Mirror symmetry, Chaos theory, Transition flow, Oscillations, Channel flow |
| Abstract: | We analyse the long-time dynamics of trajectories within the stability boundary between laminar and turbulent square duct flow. If not constrained to a symmetric subspace, the edge trajectories exhibit a chaotic dynamics characterised by a sequence of alternating quiescent phases and intense bursting episodes. The dynamics reflects the different stages of the well-known near-wall streak–vortex interaction. Most of the time, the edge states feature a single streak with a number of flanking vortices attached to one of the four surrounding walls. The initially straight streak undergoes a linear instability and eventually breaks in an intense bursting event. At the same time, the downstream vortices give rise to a new low-speed streak at one of the neighbouring walls, thereby causing the turbulent activity to 'switch' from one wall to the other. If the edge dynamics is restricted to a single or twofold mirror-symmetric subspace, the bursting and wall-switching episodes become self-recurrent in time, representing the first periodic orbits found in square duct flow. In contrast to the chaotic edge states in the non-symmetric case, the imposed symmetries enforce analogue bursting cycles to simultaneously appear at two parallel opposing walls in a mirror-symmetric configuration. Both the localisation of turbulent activity to one or two walls and the wall-switching dynamics are shown to be common phenomena in marginally turbulent duct flows. We argue that such episodes represent transient visits of marginally turbulent trajectories to some of the edge states detected here. [ABSTRACT FROM AUTHOR] |
| Copyright of Journal of Fluid Mechanics is the property of Cambridge University Press and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 189178486 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Chaotic and time-periodic edge states in square duct flow. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Weyrauch%2C+Markus%22">Weyrauch, Markus</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> markus.scherer@kit.edu</i><br /><searchLink fieldCode="AR" term="%22Uhlmann%2C+Markus%22">Uhlmann, Markus</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Kawahara%2C+Genta%22">Kawahara, Genta</searchLink><relatesTo>1,2</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Journal+of+Fluid+Mechanics%22">Journal of Fluid Mechanics</searchLink>. 10/24/2025, Vol. 1021, p1-35. 35p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Turbulence%22">Turbulence</searchLink><br /><searchLink fieldCode="DE" term="%22Turbulent+flow%22">Turbulent flow</searchLink><br /><searchLink fieldCode="DE" term="%22Mirror+symmetry%22">Mirror symmetry</searchLink><br /><searchLink fieldCode="DE" term="%22Chaos+theory%22">Chaos theory</searchLink><br /><searchLink fieldCode="DE" term="%22Transition+flow%22">Transition flow</searchLink><br /><searchLink fieldCode="DE" term="%22Oscillations%22">Oscillations</searchLink><br /><searchLink fieldCode="DE" term="%22Channel+flow%22">Channel flow</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: We analyse the long-time dynamics of trajectories within the stability boundary between laminar and turbulent square duct flow. If not constrained to a symmetric subspace, the edge trajectories exhibit a chaotic dynamics characterised by a sequence of alternating quiescent phases and intense bursting episodes. The dynamics reflects the different stages of the well-known near-wall streak–vortex interaction. Most of the time, the edge states feature a single streak with a number of flanking vortices attached to one of the four surrounding walls. The initially straight streak undergoes a linear instability and eventually breaks in an intense bursting event. At the same time, the downstream vortices give rise to a new low-speed streak at one of the neighbouring walls, thereby causing the turbulent activity to 'switch' from one wall to the other. If the edge dynamics is restricted to a single or twofold mirror-symmetric subspace, the bursting and wall-switching episodes become self-recurrent in time, representing the first periodic orbits found in square duct flow. In contrast to the chaotic edge states in the non-symmetric case, the imposed symmetries enforce analogue bursting cycles to simultaneously appear at two parallel opposing walls in a mirror-symmetric configuration. Both the localisation of turbulent activity to one or two walls and the wall-switching dynamics are shown to be common phenomena in marginally turbulent duct flows. We argue that such episodes represent transient visits of marginally turbulent trajectories to some of the edge states detected here. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Journal of Fluid Mechanics is the property of Cambridge University Press and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1017/jfm.2025.10706 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 35 StartPage: 1 Subjects: – SubjectFull: Turbulence Type: general – SubjectFull: Turbulent flow Type: general – SubjectFull: Mirror symmetry Type: general – SubjectFull: Chaos theory Type: general – SubjectFull: Transition flow Type: general – SubjectFull: Oscillations Type: general – SubjectFull: Channel flow Type: general Titles: – TitleFull: Chaotic and time-periodic edge states in square duct flow. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Weyrauch, Markus – PersonEntity: Name: NameFull: Uhlmann, Markus – PersonEntity: Name: NameFull: Kawahara, Genta IsPartOfRelationships: – BibEntity: Dates: – D: 24 M: 10 Text: 10/24/2025 Type: published Y: 2025 Identifiers: – Type: issn-print Value: 00221120 Numbering: – Type: volume Value: 1021 Titles: – TitleFull: Journal of Fluid Mechanics Type: main |
| ResultId | 1 |
