ANISOTROPIC THERMOCONVECTIVE EFFECTS ON THE ONSET OF DOUBLE-DIFFUSIVECONVECTION IN A POROUS-MEDIUM

The linear stability of the thermodiffusive equilibrium of a binary mi xture of two miscible fluids in a horizontal plane porous layer is inv estigated. The linear theory is based on the normal mode analysis unde r the small amplitude assumption. The effect of anisotropic thermo-con vective currents on the stability is obtained. The effect of Prandtl n umber, ratio of diffusivities and separation parameter are presented g raphically. It is found that the thermo-convective currents have a sta bilizing effect as well as a destabilizing effect with respect to the case in which these currents are absent. We also find that either a st ationary instability or oscillatory instability can occur as the first bifurcation. Some of the results about the former problems are deduce d.