Thermosolutal magneto-convection in an anisotropic porous medium under oblique magnetic field modulation

Abstract

This study explores the linear and weakly nonlinear stability of thermosolutal magneto-convection in an anisotropic porous medium, subjected to a modulated oblique magnetic field comprising steady and time-periodic components. A linear stability analysis, employing the normal mode technique, examines the effects of the Chandrasekhar number, separation parameter, mechanical and thermal anisotropy parameters, Darcy number, and inclination angle on convective motion. Results reveal that an increase in the Chandrasekhar number enhances system stability by elevating the critical thermal Rayleigh number and stabilizing the system. For weakly nonlinear analysis, a power series expansion in the small amplitude of oblique magnetic field modulation is used, leading to the derivation of the nonlinear cubic Ginzburg–Landau equation via the regular asymptotic perturbation method. The Nusselt and Sherwood numbers are calculated to assess heat and mass transfer, with findings indicating that the Chandrasekhar number, magnetic Prandtl number, anisotropic parameters, and modulation frequency significantly stabilize the system. The modulation of the oblique magnetic field results in a maximum enhancement of 19% in heat transfer and 21% in mass transfer, compared to the unmodulated case. These results demonstrate the considerable impact of obliquely applied, time-varying magnetic field on the regulation of convective phenomena in porous medium.