---
_id: '1837'
abstract:
- lang: eng
text: 'Transition to turbulence in straight pipes occurs in spite of the linear
stability of the laminar Hagen-Poiseuille flow if both the amplitude of flow perturbations
and the Reynolds number Re exceed a minimum threshold (subcritical transition).
As the pipe curvature increases, centrifugal effects become important, modifying
the basic flow as well as the most unstable linear modes. If the curvature (tube-to-coiling
diameter d/D) is sufficiently large, a Hopf bifurcation (supercritical instability)
is encountered before turbulence can be excited (subcritical instability). We
trace the instability thresholds in the Re - d/D parameter space in the range
0.01 ≤ d/D\ ≤ 0.1 by means of laser-Doppler velocimetry and determine the point
where the subcritical and supercritical instabilities meet. Two different experimental
set-ups are used: a closed system where the pipe forms an axisymmetric torus and
an open system employing a helical pipe. Implications for the measurement of friction
factors in curved pipes are discussed.'
article_number: R3
article_processing_charge: No
article_type: original
author:
- first_name: Jakob
full_name: Kühnen, Jakob
id: 3A47AE32-F248-11E8-B48F-1D18A9856A87
last_name: Kühnen
orcid: 0000-0003-4312-0179
- first_name: P
full_name: Braunshier, P
last_name: Braunshier
- first_name: M
full_name: Schwegel, M
last_name: Schwegel
- first_name: Hendrik
full_name: Kuhlmann, Hendrik
last_name: Kuhlmann
- first_name: Björn
full_name: Hof, Björn
id: 3A374330-F248-11E8-B48F-1D18A9856A87
last_name: Hof
orcid: 0000-0003-2057-2754
citation:
ama: Kühnen J, Braunshier P, Schwegel M, Kuhlmann H, Hof B. Subcritical versus supercritical
transition to turbulence in curved pipes. Journal of Fluid Mechanics. 2015;770(5).
doi:10.1017/jfm.2015.184
apa: Kühnen, J., Braunshier, P., Schwegel, M., Kuhlmann, H., & Hof, B. (2015).
Subcritical versus supercritical transition to turbulence in curved pipes. Journal
of Fluid Mechanics. Cambridge University Press. https://doi.org/10.1017/jfm.2015.184
chicago: Kühnen, Jakob, P Braunshier, M Schwegel, Hendrik Kuhlmann, and Björn Hof.
“Subcritical versus Supercritical Transition to Turbulence in Curved Pipes.” Journal
of Fluid Mechanics. Cambridge University Press, 2015. https://doi.org/10.1017/jfm.2015.184.
ieee: J. Kühnen, P. Braunshier, M. Schwegel, H. Kuhlmann, and B. Hof, “Subcritical
versus supercritical transition to turbulence in curved pipes,” Journal of
Fluid Mechanics, vol. 770, no. 5. Cambridge University Press, 2015.
ista: Kühnen J, Braunshier P, Schwegel M, Kuhlmann H, Hof B. 2015. Subcritical versus
supercritical transition to turbulence in curved pipes. Journal of Fluid Mechanics.
770(5), R3.
mla: Kühnen, Jakob, et al. “Subcritical versus Supercritical Transition to Turbulence
in Curved Pipes.” Journal of Fluid Mechanics, vol. 770, no. 5, R3, Cambridge
University Press, 2015, doi:10.1017/jfm.2015.184.
short: J. Kühnen, P. Braunshier, M. Schwegel, H. Kuhlmann, B. Hof, Journal of Fluid
Mechanics 770 (2015).
date_created: 2018-12-11T11:54:17Z
date_published: 2015-04-08T00:00:00Z
date_updated: 2021-01-12T06:53:31Z
day: '08'
department:
- _id: BjHo
doi: 10.1017/jfm.2015.184
ec_funded: 1
external_id:
arxiv:
- '1508.06559'
intvolume: ' 770'
issue: '5'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1508.06559
month: '04'
oa: 1
oa_version: Preprint
project:
- _id: 25152F3A-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '306589'
name: Decoding the complexity of turbulence at its origin
publication: Journal of Fluid Mechanics
publication_status: published
publisher: Cambridge University Press
publist_id: '5265'
quality_controlled: '1'
scopus_import: 1
status: public
title: Subcritical versus supercritical transition to turbulence in curved pipes
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 770
year: '2015'
...