---
_id: '5943'
abstract:
- lang: eng
text: The hairpin instability of a jet in a crossflow (JICF) for a low jet-to-crossflow
velocity ratio is investigated experimentally for a velocity ratio range of R
∈ (0.14, 0.75) and crossflow Reynolds numbers ReD ∈ (260, 640). From spectral
analysis we characterize the Strouhal number and amplitude of the hairpin instability
as a function of R and ReD. We demonstrate that the dynamics of the hairpins is
well described by the Landau model, and, hence, that the instability occurs through
Hopf bifurcation, similarly to other hydrodynamical oscillators such as wake behind
different bluff bodies. Using the Landau model, we determine the precise threshold
values of hairpin shedding. We also study the spatial dependence of this hydrodynamical
instability, which shows a global behaviour.
article_processing_charge: No
article_type: original
author:
- first_name: Lukasz
full_name: Klotz, Lukasz
id: 2C9AF1C2-F248-11E8-B48F-1D18A9856A87
last_name: Klotz
orcid: 0000-0003-1740-7635
- first_name: Konrad
full_name: Gumowski, Konrad
last_name: Gumowski
- first_name: José Eduardo
full_name: Wesfreid, José Eduardo
last_name: Wesfreid
citation:
ama: Klotz L, Gumowski K, Wesfreid JE. Experiments on a jet in a crossflow in the
low-velocity-ratio regime. Journal of Fluid Mechanics. 2019;863:386-406.
doi:10.1017/jfm.2018.974
apa: Klotz, L., Gumowski, K., & Wesfreid, J. E. (2019). Experiments on a jet
in a crossflow in the low-velocity-ratio regime. Journal of Fluid Mechanics.
Cambridge University Press. https://doi.org/10.1017/jfm.2018.974
chicago: Klotz, Lukasz, Konrad Gumowski, and José Eduardo Wesfreid. “Experiments
on a Jet in a Crossflow in the Low-Velocity-Ratio Regime.” Journal of Fluid
Mechanics. Cambridge University Press, 2019. https://doi.org/10.1017/jfm.2018.974.
ieee: L. Klotz, K. Gumowski, and J. E. Wesfreid, “Experiments on a jet in a crossflow
in the low-velocity-ratio regime,” Journal of Fluid Mechanics, vol. 863.
Cambridge University Press, pp. 386–406, 2019.
ista: Klotz L, Gumowski K, Wesfreid JE. 2019. Experiments on a jet in a crossflow
in the low-velocity-ratio regime. Journal of Fluid Mechanics. 863, 386–406.
mla: Klotz, Lukasz, et al. “Experiments on a Jet in a Crossflow in the Low-Velocity-Ratio
Regime.” Journal of Fluid Mechanics, vol. 863, Cambridge University Press,
2019, pp. 386–406, doi:10.1017/jfm.2018.974.
short: L. Klotz, K. Gumowski, J.E. Wesfreid, Journal of Fluid Mechanics 863 (2019)
386–406.
date_created: 2019-02-10T22:59:15Z
date_published: 2019-03-25T00:00:00Z
date_updated: 2023-08-24T14:43:13Z
day: '25'
department:
- _id: BjHo
doi: 10.1017/jfm.2018.974
ec_funded: 1
external_id:
arxiv:
- '1902.07931'
isi:
- '000526029100016'
intvolume: ' 863'
isi: 1
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1902.07931
month: '03'
oa: 1
oa_version: Preprint
page: 386-406
project:
- _id: 260C2330-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '754411'
name: ISTplus - Postdoctoral Fellowships
publication: Journal of Fluid Mechanics
publication_status: published
publisher: Cambridge University Press
quality_controlled: '1'
scopus_import: '1'
status: public
title: Experiments on a jet in a crossflow in the low-velocity-ratio regime
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 863
year: '2019'
...
---
_id: '5878'
abstract:
- lang: eng
text: We consider the motion of a droplet bouncing on a vibrating bath of the same
fluid in the presence of a central potential. We formulate a rotation symmetry-reduced
description of this system, which allows for the straightforward application of
dynamical systems theory tools. As an illustration of the utility of the symmetry
reduction, we apply it to a model of the pilot-wave system with a central harmonic
force. We begin our analysis by identifying local bifurcations and the onset of
chaos. We then describe the emergence of chaotic regions and their merging bifurcations,
which lead to the formation of a global attractor. In this final regime, the droplet’s
angular momentum spontaneously changes its sign as observed in the experiments
of Perrard et al.
article_number: '013122'
article_processing_charge: No
article_type: original
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: Marc
full_name: Fleury, Marc
last_name: Fleury
citation:
ama: 'Budanur NB, Fleury M. State space geometry of the chaotic pilot-wave hydrodynamics.
Chaos: An Interdisciplinary Journal of Nonlinear Science. 2019;29(1). doi:10.1063/1.5058279'
apa: 'Budanur, N. B., & Fleury, M. (2019). State space geometry of the chaotic
pilot-wave hydrodynamics. Chaos: An Interdisciplinary Journal of Nonlinear
Science. AIP Publishing. https://doi.org/10.1063/1.5058279'
chicago: 'Budanur, Nazmi B, and Marc Fleury. “State Space Geometry of the Chaotic
Pilot-Wave Hydrodynamics.” Chaos: An Interdisciplinary Journal of Nonlinear
Science. AIP Publishing, 2019. https://doi.org/10.1063/1.5058279.'
ieee: 'N. B. Budanur and M. Fleury, “State space geometry of the chaotic pilot-wave
hydrodynamics,” Chaos: An Interdisciplinary Journal of Nonlinear Science,
vol. 29, no. 1. AIP Publishing, 2019.'
ista: 'Budanur NB, Fleury M. 2019. State space geometry of the chaotic pilot-wave
hydrodynamics. Chaos: An Interdisciplinary Journal of Nonlinear Science. 29(1),
013122.'
mla: 'Budanur, Nazmi B., and Marc Fleury. “State Space Geometry of the Chaotic Pilot-Wave
Hydrodynamics.” Chaos: An Interdisciplinary Journal of Nonlinear Science,
vol. 29, no. 1, 013122, AIP Publishing, 2019, doi:10.1063/1.5058279.'
short: 'N.B. Budanur, M. Fleury, Chaos: An Interdisciplinary Journal of Nonlinear
Science 29 (2019).'
date_created: 2019-01-23T08:35:09Z
date_published: 2019-01-22T00:00:00Z
date_updated: 2023-08-25T10:16:11Z
day: '22'
department:
- _id: BjHo
doi: 10.1063/1.5058279
external_id:
arxiv:
- '1812.09011'
isi:
- '000457409100028'
intvolume: ' 29'
isi: 1
issue: '1'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1812.09011
month: '01'
oa: 1
oa_version: Preprint
publication: 'Chaos: An Interdisciplinary Journal of Nonlinear Science'
publication_identifier:
eissn:
- 1089-7682
issn:
- 1054-1500
publication_status: published
publisher: AIP Publishing
quality_controlled: '1'
related_material:
link:
- relation: erratum
url: https://aip.scitation.org/doi/abs/10.1063/1.5097157
scopus_import: '1'
status: public
title: State space geometry of the chaotic pilot-wave hydrodynamics
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 29
year: '2019'
...
---
_id: '6413'
abstract:
- lang: eng
text: Phase-field methods have long been used to model the flow of immiscible fluids.
Their ability to naturally capture interface topological changes is widely recognized,
but their accuracy in simulating flows of real fluids in practical geometries
is not established. We here quantitatively investigate the convergence of the
phase-field method to the sharp-interface limit with simulations of two-phase
pipe flow. We focus on core-annular flows, in which a highly viscous fluid is
lubricated by a less viscous fluid, and validate our simulations with an analytic
laminar solution, a formal linear stability analysis and also in the fully nonlinear
regime. We demonstrate the ability of the phase-field method to accurately deal
with non-rectangular geometry, strong advection, unsteady fluctuations and large
viscosity contrast. We argue that phase-field methods are very promising for quantitatively
studying moderately turbulent flows, especially at high concentrations of the
disperse phase.
article_processing_charge: No
article_type: original
author:
- first_name: Baofang
full_name: Song, Baofang
last_name: Song
- first_name: Carlos
full_name: Plana, Carlos
last_name: Plana
- 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: Marc
full_name: Avila, Marc
last_name: Avila
citation:
ama: Song B, Plana C, Lopez Alonso JM, Avila M. Phase-field simulation of core-annular
pipe flow. International Journal of Multiphase Flow. 2019;117:14-24. doi:10.1016/j.ijmultiphaseflow.2019.04.027
apa: Song, B., Plana, C., Lopez Alonso, J. M., & Avila, M. (2019). Phase-field
simulation of core-annular pipe flow. International Journal of Multiphase Flow.
Elsevier. https://doi.org/10.1016/j.ijmultiphaseflow.2019.04.027
chicago: Song, Baofang, Carlos Plana, Jose M Lopez Alonso, and Marc Avila. “Phase-Field
Simulation of Core-Annular Pipe Flow.” International Journal of Multiphase
Flow. Elsevier, 2019. https://doi.org/10.1016/j.ijmultiphaseflow.2019.04.027.
ieee: B. Song, C. Plana, J. M. Lopez Alonso, and M. Avila, “Phase-field simulation
of core-annular pipe flow,” International Journal of Multiphase Flow, vol.
117. Elsevier, pp. 14–24, 2019.
ista: Song B, Plana C, Lopez Alonso JM, Avila M. 2019. Phase-field simulation of
core-annular pipe flow. International Journal of Multiphase Flow. 117, 14–24.
mla: Song, Baofang, et al. “Phase-Field Simulation of Core-Annular Pipe Flow.” International
Journal of Multiphase Flow, vol. 117, Elsevier, 2019, pp. 14–24, doi:10.1016/j.ijmultiphaseflow.2019.04.027.
short: B. Song, C. Plana, J.M. Lopez Alonso, M. Avila, International Journal of
Multiphase Flow 117 (2019) 14–24.
date_created: 2019-05-13T07:58:35Z
date_published: 2019-08-01T00:00:00Z
date_updated: 2023-08-25T10:19:55Z
day: '01'
department:
- _id: BjHo
doi: 10.1016/j.ijmultiphaseflow.2019.04.027
external_id:
arxiv:
- '1902.07351'
isi:
- '000474496000002'
intvolume: ' 117'
isi: 1
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1902.07351
month: '08'
oa: 1
oa_version: Preprint
page: 14-24
publication: International Journal of Multiphase Flow
publication_identifier:
issn:
- '03019322'
publication_status: published
publisher: Elsevier
quality_controlled: '1'
scopus_import: '1'
status: public
title: Phase-field simulation of core-annular pipe flow
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 117
year: '2019'
...
---
_id: '6978'
abstract:
- lang: eng
text: In pipes and channels, the onset of turbulence is initially dominated by localizedtransients, which lead to sustained turbulence through their collective dynamics. In thepresent
work, we study numerically the localized turbulence in pipe flow and elucidate
astate space structure that gives rise to transient chaos. Starting from the basin
boundaryseparating laminar and turbulent flow, we identify transverse homoclinic orbits, thepresence
of which necessitates a homoclinic tangle and chaos. A direct consequence ofthe
homoclinic tangle is the fractal nature of the laminar-turbulent boundary, which
wasconjectured in various earlier studies. By mapping the transverse intersections
between thestable and unstable manifold of a periodic orbit, we identify the gateways
that promote anescape from turbulence.
acknowledged_ssus:
- _id: ScienComp
article_processing_charge: No
article_type: original
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: Akshunna
full_name: Dogra, Akshunna
last_name: Dogra
- 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, Dogra A, Hof B. Geometry of transient chaos in streamwise-localized
pipe flow turbulence. Physical Review Fluids. 2019;4(10):102401. doi:10.1103/PhysRevFluids.4.102401
apa: Budanur, N. B., Dogra, A., & Hof, B. (2019). Geometry of transient chaos
in streamwise-localized pipe flow turbulence. Physical Review Fluids. American
Physical Society. https://doi.org/10.1103/PhysRevFluids.4.102401
chicago: Budanur, Nazmi B, Akshunna Dogra, and Björn Hof. “Geometry of Transient
Chaos in Streamwise-Localized Pipe Flow Turbulence.” Physical Review Fluids.
American Physical Society, 2019. https://doi.org/10.1103/PhysRevFluids.4.102401.
ieee: N. B. Budanur, A. Dogra, and B. Hof, “Geometry of transient chaos in streamwise-localized
pipe flow turbulence,” Physical Review Fluids, vol. 4, no. 10. American
Physical Society, p. 102401, 2019.
ista: Budanur NB, Dogra A, Hof B. 2019. Geometry of transient chaos in streamwise-localized
pipe flow turbulence. Physical Review Fluids. 4(10), 102401.
mla: Budanur, Nazmi B., et al. “Geometry of Transient Chaos in Streamwise-Localized
Pipe Flow Turbulence.” Physical Review Fluids, vol. 4, no. 10, American
Physical Society, 2019, p. 102401, doi:10.1103/PhysRevFluids.4.102401.
short: N.B. Budanur, A. Dogra, B. Hof, Physical Review Fluids 4 (2019) 102401.
date_created: 2019-11-04T10:04:01Z
date_published: 2019-10-01T00:00:00Z
date_updated: 2023-08-30T07:20:03Z
day: '01'
department:
- _id: BjHo
doi: 10.1103/PhysRevFluids.4.102401
external_id:
arxiv:
- '1810.02211'
isi:
- '000493510400001'
intvolume: ' 4'
isi: 1
issue: '10'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1810.02211
month: '10'
oa: 1
oa_version: Preprint
page: '102401'
publication: Physical Review Fluids
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: Geometry of transient chaos in streamwise-localized pipe flow turbulence
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 4
year: '2019'
...
---
_id: '7397'
abstract:
- lang: eng
text: Polymer additives can substantially reduce the drag of turbulent flows and
the upperlimit, the so called “maximum drag reduction” (MDR) asymptote is universal,
i.e. inde-pendent of the type of polymer and solvent used. Until recently, the
consensus was that,in this limit, flows are in a marginal state where only a minimal
level of turbulence activ-ity persists. Observations in direct numerical simulations
using minimal sized channelsappeared to support this view and reported long “hibernation” periods where turbu-lence
is marginalized. In simulations of pipe flow we find that, indeed, with increasingWeissenberg
number (Wi), turbulence expresses long periods of hibernation if the domainsize
is small. However, with increasing pipe length, the temporal hibernation continuouslyalters
to spatio-temporal intermittency and here the flow consists of turbulent puffs
sur-rounded by laminar flow. Moreover, upon an increase in Wi, the flow fully
relaminarises,in agreement with recent experiments. At even larger Wi, a different
instability is en-countered causing a drag increase towards MDR. Our findings
hence link earlier minimalflow unit simulations with recent experiments and confirm
that the addition of polymersinitially suppresses Newtonian turbulence and leads
to a reverse transition. The MDRstate on the other hand results from a separate
instability and the underlying dynamicscorresponds to the recently proposed state
of elasto-inertial-turbulence (EIT).
article_processing_charge: No
article_type: original
author:
- 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: George H
full_name: Choueiri, George H
id: 448BD5BC-F248-11E8-B48F-1D18A9856A87
last_name: Choueiri
- first_name: Björn
full_name: Hof, Björn
id: 3A374330-F248-11E8-B48F-1D18A9856A87
last_name: Hof
orcid: 0000-0003-2057-2754
citation:
ama: Lopez Alonso JM, Choueiri GH, Hof B. Dynamics of viscoelastic pipe flow at
low Reynolds numbers in the maximum drag reduction limit. Journal of Fluid
Mechanics. 2019;874:699-719. doi:10.1017/jfm.2019.486
apa: Lopez Alonso, J. M., Choueiri, G. H., & Hof, B. (2019). Dynamics of viscoelastic
pipe flow at low Reynolds numbers in the maximum drag reduction limit. Journal
of Fluid Mechanics. CUP. https://doi.org/10.1017/jfm.2019.486
chicago: Lopez Alonso, Jose M, George H Choueiri, and Björn Hof. “Dynamics of Viscoelastic
Pipe Flow at Low Reynolds Numbers in the Maximum Drag Reduction Limit.” Journal
of Fluid Mechanics. CUP, 2019. https://doi.org/10.1017/jfm.2019.486.
ieee: J. M. Lopez Alonso, G. H. Choueiri, and B. Hof, “Dynamics of viscoelastic
pipe flow at low Reynolds numbers in the maximum drag reduction limit,” Journal
of Fluid Mechanics, vol. 874. CUP, pp. 699–719, 2019.
ista: Lopez Alonso JM, Choueiri GH, Hof B. 2019. Dynamics of viscoelastic pipe flow
at low Reynolds numbers in the maximum drag reduction limit. Journal of Fluid
Mechanics. 874, 699–719.
mla: Lopez Alonso, Jose M., et al. “Dynamics of Viscoelastic Pipe Flow at Low Reynolds
Numbers in the Maximum Drag Reduction Limit.” Journal of Fluid Mechanics,
vol. 874, CUP, 2019, pp. 699–719, doi:10.1017/jfm.2019.486.
short: J.M. Lopez Alonso, G.H. Choueiri, B. Hof, Journal of Fluid Mechanics 874
(2019) 699–719.
date_created: 2020-01-29T16:05:19Z
date_published: 2019-09-10T00:00:00Z
date_updated: 2023-09-06T15:36:36Z
day: '10'
department:
- _id: BjHo
doi: 10.1017/jfm.2019.486
external_id:
arxiv:
- '1808.04080'
isi:
- '000475349900001'
intvolume: ' 874'
isi: 1
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1808.04080
month: '09'
oa: 1
oa_version: Preprint
page: 699-719
publication: Journal of Fluid Mechanics
publication_identifier:
eissn:
- 1469-7645
issn:
- 0022-1120
publication_status: published
publisher: CUP
quality_controlled: '1'
scopus_import: '1'
status: public
title: Dynamics of viscoelastic pipe flow at low Reynolds numbers in the maximum drag
reduction limit
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 874
year: '2019'
...