Le problème de frontières libres en magnétodynamique des liquides avec champs magnétiques alternatifs : aspects fondamentaux et applications

摘要

The possibilities of control of shape, position and stability of the free surface of an electrically conductive medium by using alternating magnetic fields are examined. Particular attention is paid to applications regarding the implementation on the metallurgical process for the direct casting of thin products: electromagnetic forming liquids tapes of large width, electromagnetic guiding of liquid metal sheets, determination of the optimum stability conditions during the impact of a liquid film on the edge of a rotating wheel. The equilibrium of the free surface shape of a liquid in levitation, that of a meniscus centered on an inductor ring and that of a liquid column placed in a uniform magnetic field are determined. These calculations rely on technicalof boundary elements method and of variational principle. In each case, calculations and experiments are compared. The stability criteria of the levitated meniscus in the horizontal continuous casting process is determined by an normal modes analysis.