Thermosolutal convection in a ferromagnetic fluid saturating a porous medium

The thermosolutal convection in ferrofluid saturating a porous medium is considered for a ferromagnetic fluid layer heated and soluted from below in the presence of a uniform magnetic field. Using the linearized stability theory and normal mode analysis, the exact solutions are obtained for the case of two free boundaries. For the case of stationary convection, the medium permeability and non-buoyancy magnetization both have destabilizing effects on the system, whereas a stable solute gradient has a stabilizing effect on the system. The critical magnetic thermal Rayleigh number for the onset of instability is also determined. Graphs have been plotted by giving numerical values to the parameters, to depict the stability characteristics. The principle of exchange of stabilities is found to hold true for the ferromagnetic fluid saturating a porous medium heated from below in the absence of a stable solute gradient. The oscillatory modes are introduced due to the presence of the stable solute gradient, which were nonexistent in its absence. A sufficient condition for the nonexistence of overstability is also obtained.