Based on the induced magnetic field of the conducted melt in a rectangular pipe,the 2-dimensional flow field is computed,then the inclusion trajectories are obtained by solving the MHD equations and the particle trajectory equations,respectively.Results show that the induced magnetic field is apt to produce convection in a square pipe,and thus to disturb the inclusion migration.To avoid it,the pipe with rectangular or circular cross section is better to be applied than one with square cross section for the electromagnetic purification.On the other hand,the induced magnetic field has an in built tendency of self limit,which makes it possible to remove inclusion from liquid melts only with currents (DC or AC) rather than with extra magnetic fields.

By using the quasi-3D coupled current method presented, the influences of structure of cold crucible, power frequency, electricity property of charge(melt), coil(inductor)position and current on the electromagnetic field(EMF) and the levitation characteristics in the melting processes are analyzed. It is shown that in the melting process, power frequency and crucible structure are the decisive factors for the ability of penetrating magnetic flux into cold crucible. The magnetic flux density in cold crucible is reduced with the rising of power frequency, and this tendency becomes stronger when that is higher than 100 kHz. The segmented structure of cold crucible can reduce the induction eddy in itself effectively, and the higher the power frequency is, the better the result is. So, a cold crucible can be segmented into(16~20) sectors for higher frequency electromagnetic field(f>100 kHz),(8~12) sectors for high frequency one(10 kHz≤f≤100kHz), and(4~8) sectors for mid-high frequency one(f<10 kHz). It is also shown that the levitation force in melting charge is related to coil current as a parabolic function.