Ambivalent effects of added layers on steady kinematic dynamos in cylindrical geometry: application to the VKS experiment

dc.creatorStefani, F.
dc.creatorXu, M.
dc.creatorGerbeth, G.
dc.creatorRavelet, F.
dc.creatorChiffaudel, A.
dc.creatorDaviaud, F.
dc.creatorLéorat, J.
dc.date2005-11-17
dc.date2006-02-21
dc.date.accessioned2026-07-07T07:36:06Z
dc.date.available2026-07-07T07:36:06Z
dc.descriptionThe intention of the ''von Karman sodium'' (VKS) experiment is to study the hydromagnetic dynamo effect in a highly turbulent and unconstrained flow. Much effort has been devoted to the optimization of the mean flow and the lateral boundary conditions in order to minimize the critical magnetic Reynolds number and hence the necessary motor power. The main focus of this paper lies on the role of ''lid layers'', i.e. layers of liquid sodium between the impellers and the end walls of the cylinder. First, we study an analytical test flow to show that lid layers can have an ambivalent effect on the efficiency of the dynamo. The critical magnetic Reynolds number shows a flat minimum for a small lid layer thickness, but increases for thicker layers. For the actual VKS geometry it is shown that static lid layers yield a moderate increase of the critical magnetic Reynolds number by approximately 12 per cent. A more dramatic increase by 100 until 150 per cent can occur when some rotational flow is taken into account in those layers. Possible solutions of this problem are discussed for the real dynamo facility.
dc.description24 pages, 11 figures, minor changes, to appear in European Journal of Mechanics B/Fluids
dc.identifierhttps://arxiv.org/abs/physics/0511149
dc.identifierhttp://arxiv.org/abs/physics/0511149
dc.identifierEur.J.Mech.B Fluids 25 (2006) 894-908
dc.identifierdoi:10.1016/j.euromechflu.2006.02.002
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/120315
dc.subjectFluid Dynamics
dc.subjectAstrophysics
dc.subjectPlasma Physics
dc.titleAmbivalent effects of added layers on steady kinematic dynamos in cylindrical geometry: application to the VKS experiment
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