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Bistability between a stationary and an oscillatory dynamo in a turbulent flow of liquid sodium

Published online by Cambridge University Press:  16 November 2009

M. BERHANU ,
B. GALLET ,
R. MONCHAUX ,
M. BOURGOIN ,
PH. ODIER ,
J.-F. PINTON ,
N. PLIHON ,
R. VOLK ,
S. FAUVE  and
N. MORDANT
...Show all authors
M. BERHANU
Affiliation:
Laboratoire de Physique Statistique, École Normale Supérieure CNRS UMR8550, 24 rue Lhomond, F-75005 Paris, France
B. GALLET
Affiliation:
Laboratoire de Physique Statistique, École Normale Supérieure CNRS UMR8550, 24 rue Lhomond, F-75005 Paris, France
R. MONCHAUX
Affiliation:
Service de Physique de l'État Condensé, Direction des Sciences de la Matière CNRS URA 2464, CEA-Saclay, F-91191 Gif-sur-Yvette, France
M. BOURGOIN
Affiliation:
Laboratoire de Physique, École Normale Supérieure de Lyon, CNRS UMR5672, 46 allée d'Italie, F-69364 Lyon, France
PH. ODIER
Affiliation:
Laboratoire de Physique, École Normale Supérieure de Lyon, CNRS UMR5672, 46 allée d'Italie, F-69364 Lyon, France
J.-F. PINTON
Affiliation:
Laboratoire de Physique, École Normale Supérieure de Lyon, CNRS UMR5672, 46 allée d'Italie, F-69364 Lyon, France
N. PLIHON
Affiliation:
Laboratoire de Physique, École Normale Supérieure de Lyon, CNRS UMR5672, 46 allée d'Italie, F-69364 Lyon, France
R. VOLK
Affiliation:
Laboratoire de Physique, École Normale Supérieure de Lyon, CNRS UMR5672, 46 allée d'Italie, F-69364 Lyon, France
S. FAUVE*
Affiliation:
Laboratoire de Physique Statistique, École Normale Supérieure CNRS UMR8550, 24 rue Lhomond, F-75005 Paris, France
N. MORDANT
Affiliation:
Laboratoire de Physique Statistique, École Normale Supérieure CNRS UMR8550, 24 rue Lhomond, F-75005 Paris, France
F. PÉTRÉLIS
Affiliation:
Laboratoire de Physique Statistique, École Normale Supérieure CNRS UMR8550, 24 rue Lhomond, F-75005 Paris, France
S. AUMAÎTRE
Affiliation:
Service de Physique de l'État Condensé, Direction des Sciences de la Matière CNRS URA 2464, CEA-Saclay, F-91191 Gif-sur-Yvette, France
A. CHIFFAUDEL
Affiliation:
Service de Physique de l'État Condensé, Direction des Sciences de la Matière CNRS URA 2464, CEA-Saclay, F-91191 Gif-sur-Yvette, France
F. DAVIAUD
Affiliation:
Service de Physique de l'État Condensé, Direction des Sciences de la Matière CNRS URA 2464, CEA-Saclay, F-91191 Gif-sur-Yvette, France
B. DUBRULLE
Affiliation:
Service de Physique de l'État Condensé, Direction des Sciences de la Matière CNRS URA 2464, CEA-Saclay, F-91191 Gif-sur-Yvette, France
F. RAVELET
Affiliation:
Service de Physique de l'État Condensé, Direction des Sciences de la Matière CNRS URA 2464, CEA-Saclay, F-91191 Gif-sur-Yvette, France
*
Email address for correspondence: [email protected]
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Abstract

We report the first experimental observation of a bistable dynamo regime. A turbulent flow of liquid sodium is generated between two disks in the von Kármán geometry (VKS experiment). When one disk is kept at rest, bistability is observed between a stationary and an oscillatory magnetic field. The stationary and oscillatory branches occur in the vicinity of a codimension-two bifurcation that results from the coupling between two modes of magnetic field. We present an experimental study of the two regimes and study in detail the region of bistability that we understand in terms of dynamical system theory. Despite the very turbulent nature of the flow, the bifurcations of the magnetic field are correctly described by a low-dimensional model. In addition, the different regimes are robust; i.e. turbulent fluctuations do not drive any transition between the oscillatory and stationary states in the region of bistability.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 641 , 25 December 2009 , pp. 217 - 226
Copyright
Copyright © Cambridge University Press 2009

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Footnotes

†

Present address: ENSTA-UME, chemin de la Hunière, 91761 Palaiseau Cedex, France

‡

Present address: LEGI, CNRS UMR 5519, BP53, F-38041 Grenoble, France

‖

Present address: LEMFI, ENSAM, 151 bld de l'Hôpital, 75013 Paris, France

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