Kinematic alpha Tensors and Dynamo Mechanisms in a von Karman Swirling Flow

Florent Ravelet (1) , Bérengère Dubrulle (2) , François Daviaud (2) , Pierre-Arthur Ratié (1)

1 DynFluid - Laboratoire de Dynamique des Fluides
2 SPEC - UMR3680 - Service de physique de l'état condensé

We provide experimental and numerical evidence of in-blades vortices in the von Karman swirling flow. We estimate the associated kinematic alpha-effect tensor and show that it is compatible with recent models of the von Karman sodium (VKS) dynamo. We further show that depending on the relative frequency of the two impellers, the dominant dynamo mechanism may switch from alpha^2 to alpha-omega dynamo. We discuss some implications of these results for VKS experiments.

Domaines: Dynamique des Fluides [physics.flu-dyn]

Florent Ravelet, Bérengère Dubrulle, François Daviaud, Pierre-Arthur Ratié. Kinematic alpha Tensors and Dynamo Mechanisms in a von Karman Swirling Flow. Physical Review Letters, 2012, 109, pp.024503. ⟨10.1103/PhysRevLett.109.024503⟩. ⟨hal-00726771⟩