CONVECTIVE INSTABILITY IN A HORIZONTAL POROUS LAYER SATURATED WITH A CHEMICALLY REACTING FLUID

A linear stability analysis has been performed to study the onset of c onvective instability in a horizontal inert porous layer saturated wit h a fluid undergoing zero-order exothermic chemical reactions. The hor izontal porous layer is cooled from the upper boundary while two diffe rent thermal boundary conditions are imposed at the lower boundary, i. e. an isothermal wall and an adiabatic wall. The resulting eigenvalue problems were solved approximately using a single-term Galerkin method that gives the critical Rayleigh number and the associate wave number at a given Frank-Kamenetskii number. It is found that, with chemical reactions, the fluid in the porous medium is more prone to instability as compared to the case in which chemical reactions are absent.