EFFECT OF CROSS-DIFFUSION ON THE ONSET OF DOUBLE-DIFFUSIVE REACTION CONVECTION IN A POROUS LAYER

This article presents linear and weak nonlinear stability analyses of a dense porous layer saturated with a binary fluid mixture heated and salted from below in the presence of Soret and Dufour effects and chemical equilibrium on the boundaries. The Darcy model is employed as a momentum equation. A linear stability analysis is performed to investigate how the dissolution or precipitation of reactive component and the cross-diffusions affect the onset of double-diffusive convection. It is found that there is competition between the processes of thermal and solute diffusions, chemical reactions, and cross-diffusions that causes the convective instability to set in as an oscillatory mode rather than as stationary. The effects of reaction parameter, Soret parameter, Dufour parameter, solute Rayleigh number, Lewis number, and normalized porosity on the stability of the system are investigated. A weak nonlinear theory based on the truncated Fourier series method is used to find the finite-amplitude Rayleigh, Nusselt, and Sherwood numbers.