Instability and transfer at the liquid/liquid metal interface submitted or not to the action of a magnetic field. Part II

M. Al Radi - A. Hassan - G. Cognet

LEGI/PAMIR -- CNRS/INPG, BP 53, 38041 Grenoble Cedex 09, FRANCE

Abstract
A flow of liquid (aqueous solution) is realized in a cylindrical vessel with a rotating lid and a fixed bottom. A small annular channel is carved at the bottom and filled with a liquid metal (gallium) (Fig.~1). This metal is submitted or not to a rotating magnetic field according the same symmetrical axis as the vessel. We observe similar transfer laws in the solid/liquid and liquid/liquid cases for the laminar flow using experimental, numerical and analytical means; on the contrary, it results in a great difference in the turbulent flow. This important feature is explained by the occurrence of waves at the liquid/liquid interface, which strongly ehnance the transfer. We treat the occurrence of the periodic instability following a Kelvin--Helmholtz type analysis; and we show from the experiments the dominating role of the interfacial tension and viscosity over instability. The influence of a magnetic field on the characteristics of the flow is also discussed. Figs 6, Refs 5.