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effet dynamo

Effet dynamo dans des géométries cylindriques

Effet dynamo dans des géométries cylindriques

... un effet dynamo au-delà d’un nombre de Reynolds magnétique critique Rm c ≈ ...L’effet dynamo est observé uniquement avec des turbines en fer doux et pas avec des turbines en ...de dynamo ...

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Etude d'un écoulement en précession. Transition vers la turbulence et application à l'effet dynamo.

Etude d'un écoulement en précession. Transition vers la turbulence et application à l'effet dynamo.

... On a vu que les deux premières dynamos fluides réussies de 1999 sont basées sur des dy- namos «théoriques», publiées plus de trente ans auparavant, périodique (G.O. Roberts) [99] ou invariante selon une direction ...

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Effet Dynamo : Etudes des mécanismes d'instabilité et de saturation du champ magnétique

Effet Dynamo : Etudes des mécanismes d'instabilité et de saturation du champ magnétique

... “l’effet dynamo solide” qu’il d´ecrit ainsi dans le cas du Soleil: “Such internal motion induces an electrical field acting on the moving matter: and if any conducting path around the solar axis happens to be ...

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Mécanique statistique et effet dynamo dans un écoulement de von Karman turbulent

Mécanique statistique et effet dynamo dans un écoulement de von Karman turbulent

... Fig. 6.2: Sch´ema de la dynamo homopolaire de Bullard. ferromagn´etique connu ne serait capable d’y produire un champ magn´etique. Les dynamiques vari´ees d´ecrites au paragraphe pr´ec´edent poussent elles-mˆemes ...

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Champs magnétiques générés par effet dynamo dans les objets astrophysiques en rotation

Champs magnétiques générés par effet dynamo dans les objets astrophysiques en rotation

... De plus, consid´erer ` a la fois champ magn´etique et rotation paraˆıt indispensable pour l’´etude des dynamos astrophysiques, vu que les corps c´elestes sont pour la plupart soumis ` a [r] ...

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Effet dynamo et turbulence magnétohydrodynamique sous-critiques dans les disques d'accrétion

Effet dynamo et turbulence magnétohydrodynamique sous-critiques dans les disques d'accrétion

... Avec la d´ecouverte de l’instabilit´e magn´etorotationnelle, dont la propri´et´e essentielle est de g´en´erer de la turbulence en pr´esence d’un champ magn´etique, il est cependant deven[r] ...

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The turbulent dynamo as an instability in a noisy medium

The turbulent dynamo as an instability in a noisy medium

... tential growth in the dynamo regime. This back reaction is provided through the velocity which is subject to the Lorentz-Force, a quadratic form of B. It is usually ignored in the so-called kinematic regime. ...

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Large-scale dynamo produced by negative magnetic eddy diffusivities

Large-scale dynamo produced by negative magnetic eddy diffusivities

... Arguments in favor of negative magnetic eddy diffusivities were previously given in Roberts (1972) and Kraichnan (1976). The atten­ tion in Roberts (1972) was mainly concentrated on a-type dynamo, but some ...

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Magnetar formation through a convective dynamo in protoneutron stars

Magnetar formation through a convective dynamo in protoneutron stars

... 40. C. Jones, A dynamo model of Jupiter’s magnetic field. Icarus 241, 148 (2014). Acknowledgments: We thank R. Bollig, M. Bugli, T. Foglizzo, B. Gallet, D. Götz, and A. Reboul-Salze for the discussions and ...

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Dynamo threshold detection in the von Kármán sodium experiment

Dynamo threshold detection in the von Kármán sodium experiment

... Dynamo instability has indeed been observed when the flow is driven by soft-iron impellers fitted with straight blades, with a higher critical magnetic Reynolds number ∼60 for run V tha[r] ...

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The Lorentz force effect on the On-Off dynamo intermittency

The Lorentz force effect on the On-Off dynamo intermittency

... criticality dynamo is changed as the kinematic Reynolds is varied, and what is the effect of the Lorentz force in the non-linear stage of the ...the dynamo in the non-linear stage by quench- ing the ...

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Prédiction du cycle solaire en utilisant un modèle dynamo de type Babcock-Leighton

Prédiction du cycle solaire en utilisant un modèle dynamo de type Babcock-Leighton

... Une simplification utilisée pour résoudre les équations de la MHD dans un contexte de dynamo solaire et d’établir le régime cinématique dans lequel on fixe les écoulements v. L’équation 2.2 devient simplement ∂ ...

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Dynamo regimes and transitions in the VKS experiment

Dynamo regimes and transitions in the VKS experiment

... 5 Low dimensional dynamics 5.1 Observations In order to understand better the observed transitions, we can display a cut in the phase space for the magnetic field recorded in one location, by representing a component of ...

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Effect of the Lorentz force on on-off dynamo intermittency

Effect of the Lorentz force on on-off dynamo intermittency

... The first examined Reynolds number beyond the laminar regime is Gr= 12.75 共run II兲. In this case two stable solutions of the Navier-Stokes equations coexist. Depending on the initial condition, this hydrodynamic system ...

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Water experiments related to the ``Von Kármán Sodium'' Dynamo Project

Water experiments related to the ``Von Kármán Sodium'' Dynamo Project

... Abstract. The purpose of the "Von Karman Sodium" (V.K.S.) experiment is to study the "Dynamo Effect", namely the spontaneous generation of magnetic field in a flow of electrically conducting fluid. ...

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Topology and field strength in spherical, anelastic dynamo simulations

Topology and field strength in spherical, anelastic dynamo simulations

... LRA,Département de Physique, École normale supérieure, Paris A BSTRACT Dynamo action, i.e. the self-amplification of a magnetic field by the flow of an electrically con- ducting fluid, is considered to be the main ...

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Global bifurcations to subcritical magnetorotational dynamo action in Keplerian shear flow

Global bifurcations to subcritical magnetorotational dynamo action in Keplerian shear flow

... Magnetorotational dynamo action in Keplerian shear flow is a three-dimensional, non- linear magnetohydrodynamic process whose study is relevant to the understanding of accretion processes and magnetic field ...

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DYNAMO-MAS: a multi-agent system for ontology evolution from text

DYNAMO-MAS: a multi-agent system for ontology evolution from text

... of DYNAMO- MAS use only a local knowledge and behavior to evaluate their relations with other agents, which is expected to set them at their best place in the ...called DYNAMO - Virtual Ontologist Proposals ...

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Towards a 3D dynamo model of the PMS star BP Tau

Towards a 3D dynamo model of the PMS star BP Tau

... for the magnetic field is perfect conductor at the inner edge and potential at the outer edge. Then, we initialize the mag- netic computation with a multipole l = 3, m = 2 seed field where the mean magnetic energy is ...

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DYNAMO-MAS: a multi-agent system for ontology evolution from text

DYNAMO-MAS: a multi-agent system for ontology evolution from text

... of DYNAMO- MAS use only a local knowledge and behavior to evaluate their relations with other agents, which is expected to set them at their best place in the ...called DYNAMO - Virtual Ontologist Proposals ...

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