Please use this identifier to cite or link to this item:
https://hdl.handle.net/2440/138709
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DC Field | Value | Language |
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dc.contributor.author | Guerrero, B. | - |
dc.contributor.author | Lambert, M.F. | - |
dc.contributor.author | Chin, R.C. | - |
dc.date.issued | 2023 | - |
dc.identifier.citation | Journal of Fluid Mechanics, 2023; 962:A44-1-A44-32 | - |
dc.identifier.issn | 0022-1120 | - |
dc.identifier.issn | 1469-7645 | - |
dc.identifier.uri | https://hdl.handle.net/2440/138709 | - |
dc.description.abstract | This investigation characterises the time response and the transient turbulence dynamics undergone by rapidly decelerating turbulent pipe flows. A series of direct numerical simulations of decelerating flows between two steady Reynolds numbers were conducted for this purpose. The statistical analyses reveal that rapidly decelerating turbulent flows undergo four coherent, unambiguous transitional stages: inertial (stage I), a dramatic change of sign in the viscous force associated with the decay of the viscous shear stress at the wall together with a mild turbulence decay in the viscous sublayer; friction recovery (stage II), a recovery in viscous force and progressive decay in the turbulent inertia at the near-wall region; turbulence decay (stage III), a balanced decay in both turbulent inertia and viscous force at the near-wall and overlap regions; core relaxation (stage IV), slow turbulence decay at the core region. The FIK identity derived by Fukagata, Iwamoto and Kasagi (Phys. Fluids, vol. 14, 2002, L73–L76) was used to understand further how the flow dynamics influence the time response of the skin friction coefficient (Cf). The results show that although Cf plateaus during the fourth stage, the turbulent contribution keeps decaying, undershoots and finally recovers to attain its final steady value. The time evolution of the azimuthal vorticity (ωθ ) flux reveals that as the flow is decelerated, a layer of negative ωθ is produced at the wall during the flow excursion. As time progresses, this negative vorticity propagates in the wall-normal direction, attenuating the pre-existing vorticity and producing a decay in the turbulence levels. | - |
dc.description.statementofresponsibility | Byron Guerrero, Martin F. Lambert, and Rey C. Chin | - |
dc.language.iso | en | - |
dc.publisher | Cambridge University Press (CUP) | - |
dc.rights | © The Author(s), 2023. Published by Cambridge University Press. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/ licenses/by/4.0), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited. | - |
dc.source.uri | http://dx.doi.org/10.1017/jfm.2023.294 | - |
dc.subject | pipe flow; turbulence simulation; turbulent transition | - |
dc.title | Transient behaviour of decelerating turbulent pipe flows | - |
dc.type | Journal article | - |
dc.identifier.doi | 10.1017/jfm.2023.294 | - |
dc.relation.grant | ARC | - |
pubs.publication-status | Published | - |
dc.identifier.orcid | Lambert, M.F. [0000-0001-8272-6697] | - |
dc.identifier.orcid | Chin, R.C. [0000-0002-2709-4321] | - |
Appears in Collections: | Civil and Environmental Engineering publications |
Files in This Item:
File | Description | Size | Format | |
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hdl_138709.pdf | Published version | 2.96 MB | Adobe PDF | View/Open |
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