---
_id: '291'
abstract:
- lang: eng
text: Over the past decade, the edge of chaos has proven to be a fruitful starting
point for investigations of shear flows when the laminar base flow is linearly
stable. Numerous computational studies of shear flows demonstrated the existence
of states that separate laminar and turbulent regions of the state space. In addition,
some studies determined invariant solutions that reside on this edge. In this
paper, we study the unstable manifold of one such solution with the aid of continuous
symmetry reduction, which we formulate here for the simultaneous quotiening of
axial and azimuthal symmetries. Upon our investigation of the unstable manifold,
we discover a previously unknown traveling-wave solution on the laminar-turbulent
boundary with a relatively complex structure. By means of low-dimensional projections,
we visualize different dynamical paths that connect these solutions to the turbulence.
Our numerical experiments demonstrate that the laminar-turbulent boundary exhibits
qualitatively different regions whose properties are influenced by the nearby
invariant solutions.
article_number: '054401'
article_processing_charge: No
author:
- first_name: Nazmi B
full_name: Budanur, Nazmi B
id: 3EA1010E-F248-11E8-B48F-1D18A9856A87
last_name: Budanur
orcid: 0000-0003-0423-5010
- first_name: Björn
full_name: Hof, Björn
id: 3A374330-F248-11E8-B48F-1D18A9856A87
last_name: Hof
orcid: 0000-0003-2057-2754
citation:
ama: Budanur NB, Hof B. Complexity of the laminar-turbulent boundary in pipe flow.
Physical Review Fluids. 2018;3(5). doi:10.1103/PhysRevFluids.3.054401
apa: Budanur, N. B., & Hof, B. (2018). Complexity of the laminar-turbulent boundary
in pipe flow. Physical Review Fluids. American Physical Society. https://doi.org/10.1103/PhysRevFluids.3.054401
chicago: Budanur, Nazmi B, and Björn Hof. “Complexity of the Laminar-Turbulent Boundary
in Pipe Flow.” Physical Review Fluids. American Physical Society, 2018.
https://doi.org/10.1103/PhysRevFluids.3.054401.
ieee: N. B. Budanur and B. Hof, “Complexity of the laminar-turbulent boundary in
pipe flow,” Physical Review Fluids, vol. 3, no. 5. American Physical Society,
2018.
ista: Budanur NB, Hof B. 2018. Complexity of the laminar-turbulent boundary in pipe
flow. Physical Review Fluids. 3(5), 054401.
mla: Budanur, Nazmi B., and Björn Hof. “Complexity of the Laminar-Turbulent Boundary
in Pipe Flow.” Physical Review Fluids, vol. 3, no. 5, 054401, American
Physical Society, 2018, doi:10.1103/PhysRevFluids.3.054401.
short: N.B. Budanur, B. Hof, Physical Review Fluids 3 (2018).
date_created: 2018-12-11T11:45:39Z
date_published: 2018-05-30T00:00:00Z
date_updated: 2023-09-11T12:45:44Z
day: '30'
department:
- _id: BjHo
doi: 10.1103/PhysRevFluids.3.054401
external_id:
arxiv:
- '1802.01918'
isi:
- '000433426200001'
intvolume: ' 3'
isi: 1
issue: '5'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1802.01918
month: '05'
oa: 1
oa_version: Preprint
publication: Physical Review Fluids
publication_status: published
publisher: American Physical Society
publist_id: '7590'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Complexity of the laminar-turbulent boundary in pipe flow
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 3
year: '2018'
...
---
_id: '17'
abstract:
- lang: eng
text: Creeping flow of polymeric fluid without inertia exhibits elastic instabilities
and elastic turbulence accompanied by drag enhancement due to elastic stress produced
by flow-stretched polymers. However, in inertia-dominated flow at high Re and
low fluid elasticity El, a reduction in turbulent frictional drag is caused by
an intricate competition between inertial and elastic stresses. Here we explore
the effect of inertia on the stability of viscoelastic flow in a broad range of
control parameters El and (Re,Wi). We present the stability diagram of observed
flow regimes in Wi-Re coordinates and find that the instabilities' onsets show
an unexpectedly nonmonotonic dependence on El. Further, three distinct regions
in the diagram are identified based on El. Strikingly, for high-elasticity fluids
we discover a complete relaminarization of flow at Reynolds number in the range
of 1 to 10, different from a well-known turbulent drag reduction. These counterintuitive
effects may be explained by a finite polymer extensibility and a suppression of
vorticity at high Wi. Our results call for further theoretical and numerical development
to uncover the role of inertial effect on elastic turbulence in a viscoelastic
flow.
article_number: '103302 '
article_processing_charge: No
author:
- first_name: Atul
full_name: Varshney, Atul
id: 2A2006B2-F248-11E8-B48F-1D18A9856A87
last_name: Varshney
orcid: 0000-0002-3072-5999
- first_name: Victor
full_name: Steinberg, Victor
last_name: Steinberg
citation:
ama: Varshney A, Steinberg V. Drag enhancement and drag reduction in viscoelastic
flow. Physical Review Fluids. 2018;3(10). doi:10.1103/PhysRevFluids.3.103302
apa: Varshney, A., & Steinberg, V. (2018). Drag enhancement and drag reduction
in viscoelastic flow. Physical Review Fluids. American Physical Society.
https://doi.org/10.1103/PhysRevFluids.3.103302
chicago: Varshney, Atul, and Victor Steinberg. “Drag Enhancement and Drag Reduction
in Viscoelastic Flow.” Physical Review Fluids. American Physical Society,
2018. https://doi.org/10.1103/PhysRevFluids.3.103302.
ieee: A. Varshney and V. Steinberg, “Drag enhancement and drag reduction in viscoelastic
flow,” Physical Review Fluids, vol. 3, no. 10. American Physical Society,
2018.
ista: Varshney A, Steinberg V. 2018. Drag enhancement and drag reduction in viscoelastic
flow. Physical Review Fluids. 3(10), 103302.
mla: Varshney, Atul, and Victor Steinberg. “Drag Enhancement and Drag Reduction
in Viscoelastic Flow.” Physical Review Fluids, vol. 3, no. 10, 103302,
American Physical Society, 2018, doi:10.1103/PhysRevFluids.3.103302.
short: A. Varshney, V. Steinberg, Physical Review Fluids 3 (2018).
date_created: 2018-12-11T11:44:11Z
date_published: 2018-10-15T00:00:00Z
date_updated: 2023-09-11T12:59:28Z
day: '15'
ddc:
- '532'
department:
- _id: BjHo
doi: 10.1103/PhysRevFluids.3.103302
ec_funded: 1
external_id:
isi:
- '000447311500001'
file:
- access_level: open_access
checksum: e1445be33e8165114e96246275600750
content_type: application/pdf
creator: system
date_created: 2018-12-12T10:10:14Z
date_updated: 2020-07-14T12:45:12Z
file_id: '4800'
file_name: IST-2018-1061-v1+1_PhysRevFluids.3.103302.pdf
file_size: 1409040
relation: main_file
file_date_updated: 2020-07-14T12:45:12Z
has_accepted_license: '1'
intvolume: ' 3'
isi: 1
issue: '10'
language:
- iso: eng
month: '10'
oa: 1
oa_version: Published Version
project:
- _id: 260C2330-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '754411'
name: ISTplus - Postdoctoral Fellowships
publication: Physical Review Fluids
publication_status: published
publisher: American Physical Society
publist_id: '8038'
pubrep_id: '1061'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Drag enhancement and drag reduction in viscoelastic flow
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 3
year: '2018'
...
---
_id: '16'
abstract:
- lang: eng
text: We report quantitative evidence of mixing-layer elastic instability in a viscoelastic
fluid flow between two widely spaced obstacles hindering a channel flow at Re
1 and Wi 1. Two mixing layers with nonuniform shear velocity profiles are formed
in the region between the obstacles. The mixing-layer instability arises in the
vicinity of an inflection point on the shear velocity profile with a steep variation
in the elastic stress. The instability results in an intermittent appearance of
small vortices in the mixing layers and an amplification of spatiotemporal averaged
vorticity in the elastic turbulence regime. The latter is characterized through
scaling of friction factor with Wi and both pressure and velocity spectra. Furthermore,
the observations reported provide improved understanding of the stability of the
mixing layer in a viscoelastic fluid at large elasticity, i.e., Wi 1 and Re 1
and oppose the current view of suppression of vorticity solely by polymer additives.
acknowledgement: This work was partially supported by the Israel Science Foundation
(ISF; Grant No. 882/15) and the Binational USA-Israel Foundation (BSF; Grant No.
2016145).
article_number: '103303'
article_processing_charge: No
article_type: original
author:
- first_name: Atul
full_name: Varshney, Atul
id: 2A2006B2-F248-11E8-B48F-1D18A9856A87
last_name: Varshney
orcid: 0000-0002-3072-5999
- first_name: Victor
full_name: Steinberg, Victor
last_name: Steinberg
citation:
ama: Varshney A, Steinberg V. Mixing layer instability and vorticity amplification
in a creeping viscoelastic flow. Physical Review Fluids. 2018;3(10). doi:10.1103/PhysRevFluids.3.103303
apa: Varshney, A., & Steinberg, V. (2018). Mixing layer instability and vorticity
amplification in a creeping viscoelastic flow. Physical Review Fluids.
American Physical Society. https://doi.org/10.1103/PhysRevFluids.3.103303
chicago: Varshney, Atul, and Victor Steinberg. “Mixing Layer Instability and Vorticity
Amplification in a Creeping Viscoelastic Flow.” Physical Review Fluids.
American Physical Society, 2018. https://doi.org/10.1103/PhysRevFluids.3.103303.
ieee: A. Varshney and V. Steinberg, “Mixing layer instability and vorticity amplification
in a creeping viscoelastic flow,” Physical Review Fluids, vol. 3, no. 10.
American Physical Society, 2018.
ista: Varshney A, Steinberg V. 2018. Mixing layer instability and vorticity amplification
in a creeping viscoelastic flow. Physical Review Fluids. 3(10), 103303.
mla: Varshney, Atul, and Victor Steinberg. “Mixing Layer Instability and Vorticity
Amplification in a Creeping Viscoelastic Flow.” Physical Review Fluids,
vol. 3, no. 10, 103303, American Physical Society, 2018, doi:10.1103/PhysRevFluids.3.103303.
short: A. Varshney, V. Steinberg, Physical Review Fluids 3 (2018).
date_created: 2018-12-11T11:44:10Z
date_published: 2018-10-16T00:00:00Z
date_updated: 2023-09-13T08:57:05Z
day: '16'
ddc:
- '532'
department:
- _id: BjHo
doi: 10.1103/PhysRevFluids.3.103303
ec_funded: 1
external_id:
isi:
- '000447469200001'
file:
- access_level: open_access
checksum: 7fc0a2322214d1c04debef36d5bf2e8a
content_type: application/pdf
creator: system
date_created: 2018-12-12T10:13:56Z
date_updated: 2020-07-14T12:45:04Z
file_id: '5043'
file_name: IST-2018-1062-v1+1_PhysRevFluids.3.103303.pdf
file_size: 1838431
relation: main_file
file_date_updated: 2020-07-14T12:45:04Z
has_accepted_license: '1'
intvolume: ' 3'
isi: 1
issue: '10'
language:
- iso: eng
month: '10'
oa: 1
oa_version: Submitted Version
project:
- _id: 260C2330-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '754411'
name: ISTplus - Postdoctoral Fellowships
publication: Physical Review Fluids
publication_status: published
publisher: American Physical Society
publist_id: '8039'
pubrep_id: '1062'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Mixing layer instability and vorticity amplification in a creeping viscoelastic
flow
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 3
year: '2018'
...
---
_id: '519'
abstract:
- lang: eng
text: 'This study treats with the influence of a symmetry-breaking transversal magnetic
field on the nonlinear dynamics of ferrofluidic Taylor-Couette flow – flow confined
between two concentric independently rotating cylinders. We detected alternating
‘flip’ solutions which are flow states featuring typical characteristics of slow-fast-dynamics
in dynamical systems. The flip corresponds to a temporal change in the axial wavenumber
and we find them to appear either as pure 2-fold axisymmetric (due to the symmetry-breaking
nature of the applied transversal magnetic field) or involving non-axisymmetric,
helical modes in its interim solution. The latter ones show features of typical
ribbon solutions. In any case the flip solutions have a preferential first axial
wavenumber which corresponds to the more stable state (slow dynamics) and second
axial wavenumber, corresponding to the short appearing more unstable state (fast
dynamics). However, in both cases the flip time grows exponential with increasing
the magnetic field strength before the flip solutions, living on 2-tori invariant
manifolds, cease to exist, with lifetime going to infinity. Further we show that
ferrofluidic flow turbulence differ from the classical, ordinary (usually at high
Reynolds number) turbulence. The applied magnetic field hinders the free motion
of ferrofluid partials and therefore smoothen typical turbulent quantities and
features so that speaking of mildly chaotic dynamics seems to be a more appropriate
expression for the observed motion. '
acknowledgement: S.Altmeyer is a Serra Húnter Fellow
article_processing_charge: No
article_type: original
author:
- first_name: Sebastian
full_name: Altmeyer, Sebastian
id: 2EE67FDC-F248-11E8-B48F-1D18A9856A87
last_name: Altmeyer
orcid: 0000-0001-5964-0203
citation:
ama: Altmeyer S. Non-linear dynamics and alternating ‘flip’ solutions in ferrofluidic
Taylor-Couette flow. Journal of Magnetism and Magnetic Materials. 2018;452:427-441.
doi:10.1016/j.jmmm.2017.12.073
apa: Altmeyer, S. (2018). Non-linear dynamics and alternating ‘flip’ solutions in
ferrofluidic Taylor-Couette flow. Journal of Magnetism and Magnetic Materials.
Elsevier. https://doi.org/10.1016/j.jmmm.2017.12.073
chicago: Altmeyer, Sebastian. “Non-Linear Dynamics and Alternating ‘Flip’ Solutions
in Ferrofluidic Taylor-Couette Flow.” Journal of Magnetism and Magnetic Materials.
Elsevier, 2018. https://doi.org/10.1016/j.jmmm.2017.12.073.
ieee: S. Altmeyer, “Non-linear dynamics and alternating ‘flip’ solutions in ferrofluidic
Taylor-Couette flow,” Journal of Magnetism and Magnetic Materials, vol.
452. Elsevier, pp. 427–441, 2018.
ista: Altmeyer S. 2018. Non-linear dynamics and alternating ‘flip’ solutions in
ferrofluidic Taylor-Couette flow. Journal of Magnetism and Magnetic Materials.
452, 427–441.
mla: Altmeyer, Sebastian. “Non-Linear Dynamics and Alternating ‘Flip’ Solutions
in Ferrofluidic Taylor-Couette Flow.” Journal of Magnetism and Magnetic Materials,
vol. 452, Elsevier, 2018, pp. 427–41, doi:10.1016/j.jmmm.2017.12.073.
short: S. Altmeyer, Journal of Magnetism and Magnetic Materials 452 (2018) 427–441.
date_created: 2018-12-11T11:46:56Z
date_published: 2018-04-15T00:00:00Z
date_updated: 2023-09-13T09:03:44Z
day: '15'
ddc:
- '530'
department:
- _id: BjHo
doi: 10.1016/j.jmmm.2017.12.073
external_id:
isi:
- '000425547700061'
file:
- access_level: open_access
checksum: 431f5cd4a628d7ca21161f82b14ccb4f
content_type: application/pdf
creator: dernst
date_created: 2020-05-14T14:41:17Z
date_updated: 2020-07-14T12:46:37Z
file_id: '7838'
file_name: 2018_Magnetism_Altmeyer.pdf
file_size: 17309535
relation: main_file
file_date_updated: 2020-07-14T12:46:37Z
has_accepted_license: '1'
intvolume: ' 452'
isi: 1
language:
- iso: eng
month: '04'
oa: 1
oa_version: Submitted Version
page: 427 - 441
publication: Journal of Magnetism and Magnetic Materials
publication_status: published
publisher: Elsevier
publist_id: '7297'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Non-linear dynamics and alternating ‘flip’ solutions in ferrofluidic Taylor-Couette
flow
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 452
year: '2018'
...
---
_id: '5996'
abstract:
- lang: eng
text: 'In pipes, turbulence sets in despite the linear stability of the laminar
Hagen–Poiseuille flow. The Reynolds number ( ) for which turbulence first appears
in a given experiment – the ‘natural transition point’ – depends on imperfections
of the set-up, or, more precisely, on the magnitude of finite amplitude perturbations.
At onset, turbulence typically only occupies a certain fraction of the flow, and
this fraction equally is found to differ from experiment to experiment. Despite
these findings, Reynolds proposed that after sufficiently long times, flows may
settle to steady conditions: below a critical velocity, flows should (regardless
of initial conditions) always return to laminar, while above this velocity, eddying
motion should persist. As will be shown, even in pipes several thousand diameters
long, the spatio-temporal intermittent flow patterns observed at the end of the
pipe strongly depend on the initial conditions, and there is no indication that
different flow patterns would eventually settle to a (statistical) steady state.
Exploiting the fact that turbulent puffs do not age (i.e. they are memoryless),
we continuously recreate the puff sequence exiting the pipe at the pipe entrance,
and in doing so introduce periodic boundary conditions for the puff pattern. This
procedure allows us to study the evolution of the flow patterns for arbitrary
long times, and we find that after times in excess of advective time units, indeed
a statistical steady state is reached. Although the resulting flows remain spatio-temporally
intermittent, puff splitting and decay rates eventually reach a balance, so that
the turbulent fraction fluctuates around a well-defined level which only depends
on . In accordance with Reynolds’ proposition, we find that at lower (here 2020),
flows eventually always resume to laminar, while for higher ( ), turbulence persists.
The critical point for pipe flow hence falls in the interval of $2020 , which
is in very good agreement with the recently proposed value of . The latter estimate
was based on single-puff statistics and entirely neglected puff interactions.
Unlike in typical contact processes where such interactions strongly affect the
percolation threshold, in pipe flow, the critical point is only marginally influenced.
Interactions, on the other hand, are responsible for the approach to the statistical
steady state. As shown, they strongly affect the resulting flow patterns, where
they cause ‘puff clustering’, and these regions of large puff densities are observed
to travel across the puff pattern in a wave-like fashion.'
acknowledgement: ' We also thank Philipp Maier and the IST Austria workshop for theirdedicated
technical support'
article_processing_charge: No
article_type: original
author:
- first_name: Mukund
full_name: Vasudevan, Mukund
id: 3C5A959A-F248-11E8-B48F-1D18A9856A87
last_name: Vasudevan
- first_name: Björn
full_name: Hof, Björn
id: 3A374330-F248-11E8-B48F-1D18A9856A87
last_name: Hof
orcid: 0000-0003-2057-2754
citation:
ama: Vasudevan M, Hof B. The critical point of the transition to turbulence in pipe
flow. Journal of Fluid Mechanics. 2018;839:76-94. doi:10.1017/jfm.2017.923
apa: Vasudevan, M., & Hof, B. (2018). The critical point of the transition to
turbulence in pipe flow. Journal of Fluid Mechanics. Cambridge University
Press. https://doi.org/10.1017/jfm.2017.923
chicago: Vasudevan, Mukund, and Björn Hof. “The Critical Point of the Transition
to Turbulence in Pipe Flow.” Journal of Fluid Mechanics. Cambridge University
Press, 2018. https://doi.org/10.1017/jfm.2017.923.
ieee: M. Vasudevan and B. Hof, “The critical point of the transition to turbulence
in pipe flow,” Journal of Fluid Mechanics, vol. 839. Cambridge University
Press, pp. 76–94, 2018.
ista: Vasudevan M, Hof B. 2018. The critical point of the transition to turbulence
in pipe flow. Journal of Fluid Mechanics. 839, 76–94.
mla: Vasudevan, Mukund, and Björn Hof. “The Critical Point of the Transition to
Turbulence in Pipe Flow.” Journal of Fluid Mechanics, vol. 839, Cambridge
University Press, 2018, pp. 76–94, doi:10.1017/jfm.2017.923.
short: M. Vasudevan, B. Hof, Journal of Fluid Mechanics 839 (2018) 76–94.
date_created: 2019-02-14T12:50:50Z
date_published: 2018-03-25T00:00:00Z
date_updated: 2023-09-19T14:37:49Z
day: '25'
department:
- _id: BjHo
doi: 10.1017/jfm.2017.923
ec_funded: 1
external_id:
arxiv:
- '1709.06372'
isi:
- '000437858300003'
intvolume: ' 839'
isi: 1
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1709.06372
month: '03'
oa: 1
oa_version: Preprint
page: 76-94
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_identifier:
eissn:
- 1469-7645
issn:
- 0022-1120
publication_status: published
publisher: Cambridge University Press
quality_controlled: '1'
scopus_import: '1'
status: public
title: The critical point of the transition to turbulence in pipe flow
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 839
year: '2018'
...
---
_id: '328'
abstract:
- lang: eng
text: The drag of turbulent flows can be drastically decreased by adding small amounts
of high molecular weight polymers. While drag reduction initially increases with
polymer concentration, it eventually saturates to what is known as the maximum
drag reduction (MDR) asymptote; this asymptote is generally attributed to the
dynamics being reduced to a marginal yet persistent state of subdued turbulent
motion. Contrary to this accepted view, we show that, for an appropriate choice
of parameters, polymers can reduce the drag beyond the suggested asymptotic limit,
eliminating turbulence and giving way to laminar flow. At higher polymer concentrations,
however, the laminar state becomes unstable, resulting in a fluctuating flow with
the characteristic drag of the MDR asymptote. Our findings indicate that the asymptotic
state is hence dynamically disconnected from ordinary turbulence. © 2018 American
Physical Society.
acknowledged_ssus:
- _id: SSU
acknowledgement: The authors thank Philipp Maier and the IST Austria workshop for
their dedicated technical support.
article_number: '124501'
article_processing_charge: No
author:
- first_name: George H
full_name: Choueiri, George H
id: 448BD5BC-F248-11E8-B48F-1D18A9856A87
last_name: Choueiri
- first_name: Jose M
full_name: Lopez Alonso, Jose M
id: 40770848-F248-11E8-B48F-1D18A9856A87
last_name: Lopez Alonso
orcid: 0000-0002-0384-2022
- first_name: Björn
full_name: Hof, Björn
id: 3A374330-F248-11E8-B48F-1D18A9856A87
last_name: Hof
orcid: 0000-0003-2057-2754
citation:
ama: Choueiri GH, Lopez Alonso JM, Hof B. Exceeding the asymptotic limit of polymer
drag reduction. Physical Review Letters. 2018;120(12). doi:10.1103/PhysRevLett.120.124501
apa: Choueiri, G. H., Lopez Alonso, J. M., & Hof, B. (2018). Exceeding the asymptotic
limit of polymer drag reduction. Physical Review Letters. American Physical
Society. https://doi.org/10.1103/PhysRevLett.120.124501
chicago: Choueiri, George H, Jose M Lopez Alonso, and Björn Hof. “Exceeding the
Asymptotic Limit of Polymer Drag Reduction.” Physical Review Letters. American
Physical Society, 2018. https://doi.org/10.1103/PhysRevLett.120.124501.
ieee: G. H. Choueiri, J. M. Lopez Alonso, and B. Hof, “Exceeding the asymptotic
limit of polymer drag reduction,” Physical Review Letters, vol. 120, no.
12. American Physical Society, 2018.
ista: Choueiri GH, Lopez Alonso JM, Hof B. 2018. Exceeding the asymptotic limit
of polymer drag reduction. Physical Review Letters. 120(12), 124501.
mla: Choueiri, George H., et al. “Exceeding the Asymptotic Limit of Polymer Drag
Reduction.” Physical Review Letters, vol. 120, no. 12, 124501, American
Physical Society, 2018, doi:10.1103/PhysRevLett.120.124501.
short: G.H. Choueiri, J.M. Lopez Alonso, B. Hof, Physical Review Letters 120 (2018).
date_created: 2018-12-11T11:45:51Z
date_published: 2018-03-19T00:00:00Z
date_updated: 2023-10-10T13:27:44Z
day: '19'
department:
- _id: BjHo
doi: 10.1103/PhysRevLett.120.124501
ec_funded: 1
external_id:
isi:
- '000427804000005'
intvolume: ' 120'
isi: 1
issue: '12'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1703.06271
month: '03'
oa: 1
oa_version: Preprint
project:
- _id: 25681D80-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '291734'
name: International IST Postdoc Fellowship Programme
- _id: 25152F3A-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '306589'
name: Decoding the complexity of turbulence at its origin
publication: Physical Review Letters
publication_status: published
publisher: American Physical Society
publist_id: '7537'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Exceeding the asymptotic limit of polymer drag reduction
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 120
year: '2018'
...
---
_id: '136'
abstract:
- lang: eng
text: Recent studies suggest that unstable, nonchaotic solutions of the Navier-Stokes
equation may provide deep insights into fluid turbulence. In this article, we
present a combined experimental and numerical study exploring the dynamical role
of unstable equilibrium solutions and their invariant manifolds in a weakly turbulent,
electromagnetically driven, shallow fluid layer. Identifying instants when turbulent
evolution slows down, we compute 31 unstable equilibria of a realistic two-dimensional
model of the flow. We establish the dynamical relevance of these unstable equilibria
by showing that they are closely visited by the turbulent flow. We also establish
the dynamical relevance of unstable manifolds by verifying that they are shadowed
by turbulent trajectories departing from the neighborhoods of unstable equilibria
over large distances in state space.
article_processing_charge: No
author:
- first_name: Balachandra
full_name: Suri, Balachandra
id: 47A5E706-F248-11E8-B48F-1D18A9856A87
last_name: Suri
- first_name: Jeffrey
full_name: Tithof, Jeffrey
last_name: Tithof
- first_name: Roman
full_name: Grigoriev, Roman
last_name: Grigoriev
- first_name: Michael
full_name: Schatz, Michael
last_name: Schatz
citation:
ama: Suri B, Tithof J, Grigoriev R, Schatz M. Unstable equilibria and invariant
manifolds in quasi-two-dimensional Kolmogorov-like flow. Physical Review E.
2018;98(2). doi:10.1103/PhysRevE.98.023105
apa: Suri, B., Tithof, J., Grigoriev, R., & Schatz, M. (2018). Unstable equilibria
and invariant manifolds in quasi-two-dimensional Kolmogorov-like flow. Physical
Review E. American Physical Society. https://doi.org/10.1103/PhysRevE.98.023105
chicago: Suri, Balachandra, Jeffrey Tithof, Roman Grigoriev, and Michael Schatz.
“Unstable Equilibria and Invariant Manifolds in Quasi-Two-Dimensional Kolmogorov-like
Flow.” Physical Review E. American Physical Society, 2018. https://doi.org/10.1103/PhysRevE.98.023105.
ieee: B. Suri, J. Tithof, R. Grigoriev, and M. Schatz, “Unstable equilibria and
invariant manifolds in quasi-two-dimensional Kolmogorov-like flow,” Physical
Review E, vol. 98, no. 2. American Physical Society, 2018.
ista: Suri B, Tithof J, Grigoriev R, Schatz M. 2018. Unstable equilibria and invariant
manifolds in quasi-two-dimensional Kolmogorov-like flow. Physical Review E. 98(2).
mla: Suri, Balachandra, et al. “Unstable Equilibria and Invariant Manifolds in Quasi-Two-Dimensional
Kolmogorov-like Flow.” Physical Review E, vol. 98, no. 2, American Physical
Society, 2018, doi:10.1103/PhysRevE.98.023105.
short: B. Suri, J. Tithof, R. Grigoriev, M. Schatz, Physical Review E 98 (2018).
date_created: 2018-12-11T11:44:49Z
date_published: 2018-08-13T00:00:00Z
date_updated: 2023-10-10T13:29:10Z
day: '13'
department:
- _id: BjHo
doi: 10.1103/PhysRevE.98.023105
external_id:
arxiv:
- '1808.02088'
isi:
- '000441466800010'
intvolume: ' 98'
isi: 1
issue: '2'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1808.02088
month: '08'
oa: 1
oa_version: Submitted Version
publication: Physical Review E
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: Unstable equilibria and invariant manifolds in quasi-two-dimensional Kolmogorov-like
flow
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 98
year: '2018'
...
---
_id: '422'
abstract:
- lang: eng
text: We show that a rather simple, steady modification of the streamwise velocity
profile in a pipe can lead to a complete collapse of turbulence and the flow fully
relaminarizes. Two different devices, a stationary obstacle (inset) and a device
which injects fluid through an annular gap close to the wall, are used to control
the flow. Both devices modify the streamwise velocity profile such that the flow
in the center of the pipe is decelerated and the flow in the near wall region
is accelerated. We present measurements with stereoscopic particle image velocimetry
to investigate and capture the development of the relaminarizing flow downstream
these devices and the specific circumstances responsible for relaminarization.
We find total relaminarization up to Reynolds numbers of 6000, where the skin
friction in the far downstream distance is reduced by a factor of 3.4 due to relaminarization.
In a smooth straight pipe the flow remains completely laminar downstream of the
control. Furthermore, we show that transient (temporary) relaminarization in a
spatially confined region right downstream the devices occurs also at much higher
Reynolds numbers, accompanied by a significant local skin friction drag reduction.
The underlying physical mechanism of relaminarization is attributed to a weakening
of the near-wall turbulence production cycle.
article_processing_charge: Yes (via OA deal)
author:
- first_name: Jakob
full_name: Kühnen, Jakob
id: 3A47AE32-F248-11E8-B48F-1D18A9856A87
last_name: Kühnen
orcid: 0000-0003-4312-0179
- first_name: Davide
full_name: Scarselli, Davide
id: 40315C30-F248-11E8-B48F-1D18A9856A87
last_name: Scarselli
orcid: 0000-0001-5227-4271
- first_name: Markus
full_name: Schaner, Markus
id: 316CE034-F248-11E8-B48F-1D18A9856A87
last_name: Schaner
- 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, Scarselli D, Schaner M, Hof B. Relaminarization by steady modification
of the streamwise velocity profile in a pipe. Flow Turbulence and Combustion.
2018;100(4):919-942. doi:10.1007/s10494-018-9896-4
apa: Kühnen, J., Scarselli, D., Schaner, M., & Hof, B. (2018). Relaminarization
by steady modification of the streamwise velocity profile in a pipe. Flow Turbulence
and Combustion. Springer. https://doi.org/10.1007/s10494-018-9896-4
chicago: Kühnen, Jakob, Davide Scarselli, Markus Schaner, and Björn Hof. “Relaminarization
by Steady Modification of the Streamwise Velocity Profile in a Pipe.” Flow
Turbulence and Combustion. Springer, 2018. https://doi.org/10.1007/s10494-018-9896-4.
ieee: J. Kühnen, D. Scarselli, M. Schaner, and B. Hof, “Relaminarization by steady
modification of the streamwise velocity profile in a pipe,” Flow Turbulence
and Combustion, vol. 100, no. 4. Springer, pp. 919–942, 2018.
ista: Kühnen J, Scarselli D, Schaner M, Hof B. 2018. Relaminarization by steady
modification of the streamwise velocity profile in a pipe. Flow Turbulence and
Combustion. 100(4), 919–942.
mla: Kühnen, Jakob, et al. “Relaminarization by Steady Modification of the Streamwise
Velocity Profile in a Pipe.” Flow Turbulence and Combustion, vol. 100,
no. 4, Springer, 2018, pp. 919–42, doi:10.1007/s10494-018-9896-4.
short: J. Kühnen, D. Scarselli, M. Schaner, B. Hof, Flow Turbulence and Combustion
100 (2018) 919–942.
date_created: 2018-12-11T11:46:23Z
date_published: 2018-01-01T00:00:00Z
date_updated: 2024-03-27T23:30:36Z
day: '01'
ddc:
- '530'
department:
- _id: BjHo
doi: 10.1007/s10494-018-9896-4
ec_funded: 1
external_id:
isi:
- '000433113900004'
file:
- access_level: open_access
checksum: d7c0bade150faabca150b0a9986e60ca
content_type: application/pdf
creator: dernst
date_created: 2018-12-17T15:52:37Z
date_updated: 2020-07-14T12:46:25Z
file_id: '5717'
file_name: 2018_FlowTurbulenceCombust_Kuehnen.pdf
file_size: 2210020
relation: main_file
file_date_updated: 2020-07-14T12:46:25Z
has_accepted_license: '1'
intvolume: ' 100'
isi: 1
issue: '4'
language:
- iso: eng
month: '01'
oa: 1
oa_version: Published Version
page: 919 - 942
project:
- _id: 25152F3A-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '306589'
name: Decoding the complexity of turbulence at its origin
publication: Flow Turbulence and Combustion
publication_status: published
publisher: Springer
publist_id: '7401'
quality_controlled: '1'
related_material:
record:
- id: '7258'
relation: dissertation_contains
status: public
scopus_import: '1'
status: public
title: Relaminarization by steady modification of the streamwise velocity profile
in a pipe
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 100
year: '2018'
...
---
_id: '461'
abstract:
- lang: eng
text: Turbulence is the major cause of friction losses in transport processes and
it is responsible for a drastic drag increase in flows over bounding surfaces.
While much effort is invested into developing ways to control and reduce turbulence
intensities, so far no methods exist to altogether eliminate turbulence if velocities
are sufficiently large. We demonstrate for pipe flow that appropriate distortions
to the velocity profile lead to a complete collapse of turbulence and subsequently
friction losses are reduced by as much as 90%. Counterintuitively, the return
to laminar motion is accomplished by initially increasing turbulence intensities
or by transiently amplifying wall shear. Since neither the Reynolds number nor
the shear stresses decrease (the latter often increase), these measures are not
indicative of turbulence collapse. Instead, an amplification mechanism measuring
the interaction between eddies and the mean shear is found to set a threshold
below which turbulence is suppressed beyond recovery.
acknowledgement: We acknowledge the European Research Council under the European Union’s
Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement 306589, the European
Research Council (ERC) under the European Union’s Horizon 2020 research and innovation
programme (grant agreement no. 737549) and the Deutsche Forschungsgemeinschaft (Project
No. FOR 1182) for financial support. We thank our technician P. Maier for providing
highly valuable ideas and greatly supporting us in all technical aspects. We thank
M. Schaner for technical drawings, construction and design. We thank M. Schwegel
for a Matlab code to post-process experimental data.
article_processing_charge: No
author:
- first_name: Jakob
full_name: Kühnen, Jakob
id: 3A47AE32-F248-11E8-B48F-1D18A9856A87
last_name: Kühnen
orcid: 0000-0003-4312-0179
- first_name: Baofang
full_name: Song, Baofang
last_name: Song
- first_name: Davide
full_name: Scarselli, Davide
id: 40315C30-F248-11E8-B48F-1D18A9856A87
last_name: Scarselli
orcid: 0000-0001-5227-4271
- first_name: Nazmi B
full_name: Budanur, Nazmi B
id: 3EA1010E-F248-11E8-B48F-1D18A9856A87
last_name: Budanur
orcid: 0000-0003-0423-5010
- first_name: Michael
full_name: Riedl, Michael
id: 3BE60946-F248-11E8-B48F-1D18A9856A87
last_name: Riedl
orcid: 0000-0003-4844-6311
- first_name: Ashley
full_name: Willis, Ashley
last_name: Willis
- first_name: Marc
full_name: Avila, Marc
last_name: Avila
- 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, Song B, Scarselli D, et al. Destabilizing turbulence in pipe flow.
Nature Physics. 2018;14:386-390. doi:10.1038/s41567-017-0018-3
apa: Kühnen, J., Song, B., Scarselli, D., Budanur, N. B., Riedl, M., Willis, A.,
… Hof, B. (2018). Destabilizing turbulence in pipe flow. Nature Physics.
Nature Publishing Group. https://doi.org/10.1038/s41567-017-0018-3
chicago: Kühnen, Jakob, Baofang Song, Davide Scarselli, Nazmi B Budanur, Michael
Riedl, Ashley Willis, Marc Avila, and Björn Hof. “Destabilizing Turbulence in
Pipe Flow.” Nature Physics. Nature Publishing Group, 2018. https://doi.org/10.1038/s41567-017-0018-3.
ieee: J. Kühnen et al., “Destabilizing turbulence in pipe flow,” Nature
Physics, vol. 14. Nature Publishing Group, pp. 386–390, 2018.
ista: Kühnen J, Song B, Scarselli D, Budanur NB, Riedl M, Willis A, Avila M, Hof
B. 2018. Destabilizing turbulence in pipe flow. Nature Physics. 14, 386–390.
mla: Kühnen, Jakob, et al. “Destabilizing Turbulence in Pipe Flow.” Nature Physics,
vol. 14, Nature Publishing Group, 2018, pp. 386–90, doi:10.1038/s41567-017-0018-3.
short: J. Kühnen, B. Song, D. Scarselli, N.B. Budanur, M. Riedl, A. Willis, M. Avila,
B. Hof, Nature Physics 14 (2018) 386–390.
date_created: 2018-12-11T11:46:36Z
date_published: 2018-01-08T00:00:00Z
date_updated: 2024-03-27T23:30:36Z
day: '08'
department:
- _id: BjHo
doi: 10.1038/s41567-017-0018-3
ec_funded: 1
external_id:
isi:
- '000429434100020'
intvolume: ' 14'
isi: 1
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1711.06543
month: '01'
oa: 1
oa_version: Preprint
page: 386-390
project:
- _id: 25152F3A-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '306589'
name: Decoding the complexity of turbulence at its origin
- _id: 25104D44-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '737549'
name: Eliminating turbulence in oil pipelines
publication: Nature Physics
publication_status: published
publisher: Nature Publishing Group
publist_id: '7360'
quality_controlled: '1'
related_material:
record:
- id: '12726'
relation: dissertation_contains
status: public
- id: '14530'
relation: dissertation_contains
status: public
- id: '7258'
relation: dissertation_contains
status: public
scopus_import: '1'
status: public
title: Destabilizing turbulence in pipe flow
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 14
year: '2018'
...
---
_id: '1211'
abstract:
- lang: eng
text: Systems such as fluid flows in channels and pipes or the complex Ginzburg–Landau
system, defined over periodic domains, exhibit both continuous symmetries, translational
and rotational, as well as discrete symmetries under spatial reflections or complex
conjugation. The simplest, and very common symmetry of this type is the equivariance
of the defining equations under the orthogonal group O(2). We formulate a novel
symmetry reduction scheme for such systems by combining the method of slices with
invariant polynomial methods, and show how it works by applying it to the Kuramoto–Sivashinsky
system in one spatial dimension. As an example, we track a relative periodic orbit
through a sequence of bifurcations to the onset of chaos. Within the symmetry-reduced
state space we are able to compute and visualize the unstable manifolds of relative
periodic orbits, their torus bifurcations, a transition to chaos via torus breakdown,
and heteroclinic connections between various relative periodic orbits. It would
be very hard to carry through such analysis in the full state space, without a
symmetry reduction such as the one we present here.
acknowledgement: 'This work was supported by the family of late G. Robinson, Jr. and
NSF Grant DMS-1211827. '
author:
- first_name: Nazmi B
full_name: Budanur, Nazmi B
id: 3EA1010E-F248-11E8-B48F-1D18A9856A87
last_name: Budanur
orcid: 0000-0003-0423-5010
- first_name: Predrag
full_name: Cvitanović, Predrag
last_name: Cvitanović
citation:
ama: Budanur NB, Cvitanović P. Unstable manifolds of relative periodic orbits in
the symmetry reduced state space of the Kuramoto–Sivashinsky system. Journal
of Statistical Physics. 2017;167(3-4):636-655. doi:10.1007/s10955-016-1672-z
apa: Budanur, N. B., & Cvitanović, P. (2017). Unstable manifolds of relative
periodic orbits in the symmetry reduced state space of the Kuramoto–Sivashinsky
system. Journal of Statistical Physics. Springer. https://doi.org/10.1007/s10955-016-1672-z
chicago: Budanur, Nazmi B, and Predrag Cvitanović. “Unstable Manifolds of Relative
Periodic Orbits in the Symmetry Reduced State Space of the Kuramoto–Sivashinsky
System.” Journal of Statistical Physics. Springer, 2017. https://doi.org/10.1007/s10955-016-1672-z.
ieee: N. B. Budanur and P. Cvitanović, “Unstable manifolds of relative periodic
orbits in the symmetry reduced state space of the Kuramoto–Sivashinsky system,”
Journal of Statistical Physics, vol. 167, no. 3–4. Springer, pp. 636–655,
2017.
ista: Budanur NB, Cvitanović P. 2017. Unstable manifolds of relative periodic orbits
in the symmetry reduced state space of the Kuramoto–Sivashinsky system. Journal
of Statistical Physics. 167(3–4), 636–655.
mla: Budanur, Nazmi B., and Predrag Cvitanović. “Unstable Manifolds of Relative
Periodic Orbits in the Symmetry Reduced State Space of the Kuramoto–Sivashinsky
System.” Journal of Statistical Physics, vol. 167, no. 3–4, Springer, 2017,
pp. 636–55, doi:10.1007/s10955-016-1672-z.
short: N.B. Budanur, P. Cvitanović, Journal of Statistical Physics 167 (2017) 636–655.
date_created: 2018-12-11T11:50:44Z
date_published: 2017-05-01T00:00:00Z
date_updated: 2021-01-12T06:49:07Z
day: '01'
ddc:
- '530'
department:
- _id: BjHo
doi: 10.1007/s10955-016-1672-z
file:
- access_level: open_access
checksum: 3e971d09eb167761aa0888ed415b0056
content_type: application/pdf
creator: system
date_created: 2018-12-12T10:18:01Z
date_updated: 2020-07-14T12:44:39Z
file_id: '5319'
file_name: IST-2017-782-v1+1_BudCvi15.pdf
file_size: 2820207
relation: main_file
file_date_updated: 2020-07-14T12:44:39Z
has_accepted_license: '1'
intvolume: ' 167'
issue: 3-4
language:
- iso: eng
month: '05'
oa: 1
oa_version: Submitted Version
page: 636-655
publication: Journal of Statistical Physics
publication_status: published
publisher: Springer
publist_id: '6136'
pubrep_id: '782'
quality_controlled: '1'
scopus_import: 1
status: public
title: Unstable manifolds of relative periodic orbits in the symmetry reduced state
space of the Kuramoto–Sivashinsky system
type: journal_article
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 167
year: '2017'
...