Magnetoconvection of a power-law fluid through a porous medium with variable gravity

Abstract

Magneto-instability of a power-law non-Newtonian fluid in a porous layer with variable gravity is investigated using linear instability theory. Four distinct forms of gravity variation, namely linear, quadratic, cubic, and exponential, are considered to examine their influence on the onset of convection. The governing equations are non-dimensionalized and analyzed using normal mode techniques under the assumption of the principle of exchange of stabilities. The novelty of the present work lies in the combined investigation of magnetic field, variable gravity, and vertical throughflow in a power-law fluid saturated porous medium. A comparative analysis of four different gravity profiles demonstrates that the exponential profile produces the strongest stabilization, while the linear profile exhibits the weakest stabilizing effect. The results reveal that the magnetic field is found to have a stabilizing influence. The gravity variation parameter consistently delays the onset of convection by redistributing the buoyancy force.