Linear and Nonlinear Gravity Field Variation on Double-Diffusive Convection in a Porous Layer

This paper analyzes the instability of a gravity field in a double-diffusive convective motion in horizontal porous matrix, heated from below uniformly with the inclusion of the Soret parameter. The critical Rayleigh numbers for the onset of stationary and oscillatory modes have been calculated by using the higher-order Gelerkin technique. We addressed four separate cases of linear and nonlinear gravity variation: (1) H(z) = - z (2) H(z) = - z2 (3) H(z) = - z3 and (4) H(z) = - (ez- 1 ). The gravity parameters Soret parameter and solute Rayleigh number on stationary and oscillatory convection and heat and mass transfer are graphically illustrated. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.