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Equilibrium  convection transition of an electroconductive fluid under simultaneous actions of gravitation, temperature, magnetic and electric fields
A. I. Raitchenko
Institute for Problems of Materials Science, Ukrainian National Academy of Sciences, 252142 Kiev, Ukraine
Abstract
The number of factors influencing the equilibriumconvection onset conditions depends radically on its electroconductivity and on temperature coefficient of electroconductivity of fluid. These factors (along with the thermal expansion in the gravitational field) include the magnetic and electric fields also. If the spatial Lorentzforce originating from the intercrossed electric and magnetic fields action is directed downwards, its effect enhances the gravitational action, and the value of critical Rayleigh number must decrease; the reverse situation (increase of critical Rayleigh number) can be observed in case of Lorentzforce directed upwards. The extent of such an influence is determined by the dimensionless complex, namely relation of the spatial Lorentzforce to the hydrostatic head of the fluid column with the unit height in the gravitational field. It is ascertained that the competition between the electromagnetic force due to nonuniformity of electroconductivity on account of its temperature dependence and the buoyancy force may have an ambiguous effect, either increase or decrease of the critical Rayleigh numbers. The effect of such a balance of actions is measured by the value of corresponding dimensionless complex which may be named as magneticelectricthermalresistivebuoyant (METRB) criterion (number). Influences of the electromagneticgravitationalhydrostatic relation number and the METRB number can strengthen or weaken one another; in particular case, they can "annihilate" mutually, and then the critical Rayleigh numbers must remain invariable. The proposed conception is useful to the analysis of situations in liquid conductors, in conductive gases (plasma), in terrestrial, planetary, and stellar atmospheres. Figs 3, Refs 34. Magnitnaya Gidrodinamika 35, No. 1, 2835, 1999 [PDF, 0.48 Mb]
Magnetohydrodynamics 35, No. 1, 2128, 1999 [PDF, 0.45 Mb]
