COMBINED EFFECT OF MAGNETIC-FIELD AND ROTATION ON THERMOSOLUTAL INSTABILITY OF A COMPRESSIBLE FLUID IN POROUS-MEDIUM

The combined effect of magnetic field and rotation on thermosolutal in stability of a compressible fluid in porous medium is considered. The system is found to be stable for (C-p/g)beta < 1 where C-p, beta, and g stand for specific heat at constant pressure, uniform adverse temper ature gradient, and acceleration due to gravity, respectively. The sta ble solute gradient, magnetic field, and rotation introduce oscillator y modes in the system for (C-p/g)beta > 1, which were nonexistent in t heir absence. For stationary convection, the stable solute gradient an d rotation have a stabilizing effect on the system for (C-p/g)beta > 1 . In the presence of rotation, the magnetic field has a stabilizing (o r destabilizing) effect, and the medium permeability has a destabilizi ng (or stabilizing) effect under certain condition, whereas in the abs ence of rotation, the magnetic field and rotation have stabilizing and destabilizing effects for (C-p/g)beta > 1, respectively, on the syste m. The sufficient conditions for the existence of overstability are ob tained.