THERMAL INSTABILITY OF HYDROMAGNETIC JEFFREY NANOFLUIDS IN POROUS MEDIA WITH VARIABLE GRAVITY FOR FREE-FREE, RIGID-RIGID, AND RIGID-FREE BOUNDARIES

Abstract

This article presents a numerical and graphical examination of thermal instability of hydromagnetic Jeffrey nanofluids in porous media with variable gravity for free-free, rigid-rigid, and rigid-free boundaries by using Galerkin technique and normal mode analysis. The Darcy model is employed. Four different gravity variable parameters: h(z) = -(e<sup>z</sup> - 1); exponential, h(z) = -z<sup>2</sup>; parabolic, h(z) = -z; and linear, h(z) = z are taken, and their effects on the Jeffrey parameter, magnetic field, moderated diffusivity ratio, porosity of porous media, Lewis number, and nanoparticle Rayleigh number on stationary convection have been calculated numerically and graphically shown for all three boundary conditions, namely free-free, rigid-rigid, and rigid-free. The necessary conditions for frequencies of the oscillatory mode under all three boundaries have been calculated. According to our research, positive linear gravity parameters make the system unstable for all three boundary conditions, but exponential gravity parameters are superior at stabilizing stationary convection for all three boundary conditions.