Bulletin of the American Physical Society
76th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 19–21, 2023; Washington, DC
Session T38: Vortex Dynamics and Vortex Flows: Turbulence
4:25 PM–6:09 PM,
Monday, November 20, 2023
Room: 204A
Chair: Wei Zhang, Cleveland State University
Abstract: T38.00005 : Coherent organizational states in turbulent pipe flow*
5:17 PM–5:30 PM
Presenter:
Robert Jäckel
(Federal University of Rio de Janeiro)
Authors:
Robert Jäckel
(Federal University of Rio de Janeiro)
Bruno Magacho
(Instituto de Física, Federal University of Rio de Janeiro)
Bayode Emmanuel Owolabi
(Instituto de Física, Universidade Federal do Rio de Janeiro)
Luca Moriconi
(Universidade Federal do Rio de Janeiro)
Juliana B Loureiro
(Federal University of Rio de Janeiro)
Turbulent pipe flow is still an essentially open area of research, boosted
in the last two decades by considerable progress achieved both on the experi-
mental and numerical frontiers, mainly centered around the identification and
characterization of coherent structures - hypothesized to be the building blocks
of turbulent dynamics. It has been a challenging task, however, to detect and
visualize these coherent states. We address, by means of stereoscopic particle
image velocimetry, that issue with the help of a large diameter (6 inches) pipe
loop, which allowed us explore coherent states at various moderate Reynolds
numbers (5300 < Re < 29000) of single-phase Newtonian flow. Although these
states have been observed at flow regimes around laminar-turbulent transition
(Re ≈ 2300) and also at high Reynolds number pipe flow (Re ≈ 35000), at mod-
erate Reynolds numbers their existence has remained largely unproven until this
study. By conditionally averaging the flow fields with respect to their dominant
azimuthal wavenumber of streamwise velocity streaks, we have been able to
uncover the existence of ten distinct coherent flow patterns. In this work, we
present their statistical weight contributions, streamwise organization, and tran-
sition dynamics. Interestingly, the weight contribution and transition dynamics
of these wavenumber states remain relativly consistent across all Reynolds num-
bers. This indicates that the Reynolds number effect—where turbulent statistics
depend on the Reynolds number in conditions of moderate turbulence—dos not
seem to be reflected in the dynamics of these COS. Moreover, their occurrence
probabilities are noted to be reasonably well described by a Poisson distribu-
tion, which suggests that the streaks are created as a Poisson process on the
pipe circular geometry.
*This research received financial support from Petrobras (ANP/Petrobras 5850.0104954.17.9 and 0050.0122372.22.9). The authors gratefully acknowledge this support.
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