Ferromagnetic Convection in a Rotating Medium with Magnetic Field Dependent Viscosity. A Correction Applied

Abstract

The effect of magnetic field dependent (MFD) viscosity on the thermal convection in a ferrofluid layer, heated from below, has been investigated in the simultaneous presence of a uniform vertical magnetic field and a uniform vertical rotation. A correction is applied to Vaidyanathan et al. (Ind. J. Pure Appl. Phy., 2001, 40, 159165), which is very important in order to predict the correct behavior of MFD viscosity. A linear stability analysis has been carried out for stationary modes and oscillatory modes separately. The critical wave number and critical Rayleigh number for the onset of instability, for the case of free boundaries, are determined numerically for sufficiently large values of the magnetic parameter ??1. Numerical results are obtained and are illustrated graphically. It is shown that MFD viscosity has a destabilizing effect on the system for the case of stationary mode and stabilizing effect for the case of oscillatory mode, whereas magnetization has a destabilizing effect. Further, it is also shown that rotation has a stabilizing effect on the system.