THERMAL CONVECTIVE INSTABILITY IN A MICROPOLAR FERROMAGNETIC FLUID SATURATED POROUS LAYER HEATED FROM BELOW

摘要

The onset of ferromagnetic convection in a micropolar ferromagnetic fluid saturated porous layer heated from below in the presence of a uniform applied vertical magnetic field has been investigated. The rigid-isothermal boundaries of the fluid layer are considered to be ferromagnetic and the eigenvalue problem is solved numerically using the Galerkin method. It is noted that the paramagnetic boundaries with large magnetic susceptibility χ mainly delay the onset of ferromagnetic convection if compared to a very low magnetic susceptibility as well as to ferromagnetic boundaries. The increase in value of the magnetic parameter M_1 and spin diffusion (couple stress) parameter N_3 is to hasten, while the increase in value of the coupling parameter N_1 and micropolar heat conduction parameter N_5 is to delay the onset of ferromagnetic convection.