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Separating large-sc...
Separating large-scale superposition and modulation in turbulent channels
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- Andreolli, Andrea (author)
- Karlsruhe Inst Technol, Inst Fluid Mech, Kaiserstr 10, D-76131 Karlsruhe, Germany.
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- Gatti, Davide (author)
- Karlsruhe Inst Technol, Inst Fluid Mech, Kaiserstr 10, D-76131 Karlsruhe, Germany.
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- Vinuesa, Ricardo (author)
- KTH,Linné Flow Center, FLOW,Strömningsmekanik och Teknisk Akustik,SimEx
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- Örlü, Ramis, 1977- (author)
- KTH,Linné Flow Center, FLOW,Strömningsmekanik och Teknisk Akustik,Karlsruhe Inst Technol, Karlsruhe, Germany.,SimEx
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- Schlatter, Philipp (author)
- KTH,Linné Flow Center, FLOW,Strömningsmekanik och Teknisk Akustik,SimEx
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Karlsruhe Inst Technol, Inst Fluid Mech, Kaiserstr 10, D-76131 Karlsruhe, Germany Linné Flow Center, FLOW (creator_code:org_t)
- 2023-03-14
- 2023
- English.
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In: Journal of Fluid Mechanics. - : Cambridge University Press (CUP). - 0022-1120 .- 1469-7645. ; 958
- Related links:
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https://doi.org/10.1...
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https://urn.kb.se/re...
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Abstract
Subject headings
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- The presence of very-large-scale motions in wall-bounded turbulent flows is commonly associated with their footprint in the form of the superposition of the large scales at the wall and the additional amplitude modulation of small-scale near-wall turbulence. These two phenomena are currently understood to be interlinked, with the superposed large-scale velocity gradient causing the modulation of small-scale activity in the proximity of the wall. To challenge this idea, we devise a numerical strategy that selectively suppresses either superposition or amplitude modulation, in an effort to isolate and study the remaining phenomenon. Results from our direct numerical simulations indicate that a positive correlation between the amplitude of the small scales in the near-wall region and the large-scale signal in the outer flow persists even when near-wall large-scale motions are suppressed - i.e. in absence of superposition. Clearly, this kind of correlation cannot be caused by the near-wall large-scale velocity or its gradients, as both are absent. Conversely, when modulation is blocked, the near-wall footprints of the large scales seem to disappear. This study has been carried out on channel flows at friction Reynolds number Re-tau = 1000 in both standard simulation domains and minimal streamwise units (MSUs), where the streamwise fluctuation energy is enhanced. The consistency of the results obtained by the two approaches suggests that MSUs can capture correctly this kind of scale interaction at a much reduced cost.
Subject headings
- TEKNIK OCH TEKNOLOGIER -- Maskinteknik -- Strömningsmekanik och akustik (hsv//swe)
- ENGINEERING AND TECHNOLOGY -- Mechanical Engineering -- Fluid Mechanics and Acoustics (hsv//eng)
Keyword
- turbulence theory
- turbulent boundary layers
Publication and Content Type
- ref (subject category)
- art (subject category)
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