Effect of rotation on ferromagnetic fluid heated and soluted from below saturating a porous medium

Abstract

The effect of rotation on thermosolutal convection in ferromagnetic fluid saturating a porous medium is considered for a fluid layer heated and soluted from below in the presence of a uniform vertical magnetic field. Using linearized stability theory and normal mode analysis, an exact solution is obtained for the case of two free boundaries. For the case of stationary convection, magnetization has a destabilizing effect whereas a stable solute gradient and rotation have stabilizing effects on the system. In the absence of rotation, the destabilizing effect of medium permeability is depicted but in the presence of rotation, medium permeability may have a destabilizing or stabilizing effect on the onset of instability. The critical wavenumber and critical magnetic thermal Rayleigh number for the onset of instability are also determined numerically for sufficiently large values of magnetic parameter M1. 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 stable solute gradient and rotation. The oscillatory modes are introduced due to the presence of the stable solute gradient and rotation, which were non-existent in their absence. A sufficient condition for the non-existence of overstability is also obtained. © 2004 Nanjing Institute of Geophysical Prospecting.