Hydrodynamics of a magnetofluidized layers in a rotating magnetic field

M. K. Bologa - I. F. Marta

Abstract
Results of studies of a magnetofluidized layer in a rotating magnetic field have been presented for the first time. Expressions for the dissipation function, phenomenological Onsager's equations as well as hydrodynamic equations of this layer have been derived applying the phenomenological approach of the continuum mechanics and thermodinamics of irreversible processes. A brief qualitative analysis and some particular solutions have been given. It has been shown that the suspended state of coarse-dispersed magnetized particles in a rotating magnetic field is possible only if the inner momentum of the disperse phase is not zero and that this state can be attained merely within a limited frequency range. The distribution of magnetc momentum of the particles was assumed to be isotropic and with this assumption the energy transferred to the magnetofuiidized layer from the magnetic field has been calculated. Equation for the determinaton of the mean value of random translation velocity of the layer particles has been derived and this value was calculated for the case of prevailing viscous dissipation. The existence of a critical frequency value of the rotating magnetic field was confirmed experimentally; at this value the inversion of the direction of the magnetofluidized layer rotation takes place, and this inversion displays hysteresis. The saturation of the dependences of (i) of particle collisions with the chamber walls on frequency and (ii) of the force moment affecting a nonmagnetic body placed in the layer on field amplitude has been observed. Figs 4, refs 25,