Onset of buoyancy-driven motion with laminar forced convection flows in a horizontal porous channel

Buoyancy-driven motion in the laminar forced convection flow has been investigated in a horizontal porous channel. The stability equations including the inertia and the dispersion effects have been solved analytically under the linear theory and also the principle of exchanges of stabilities. The resulting critical position xc for the onset of convection becomes larger with increasing the Reynolds number, ReK considering the permeability. This means that the more inertia and dispersion make the system more stable. The ionic mass transfer experiments using the limiting current technique have been conducted to obtain the critical position for the manifest convection, i.e. the undershoot distance xu with comparison of the forced convective mass flux with the mixed-convective one. Based on the experimental results, the inertia and dispersion effects are explained reasonably for the stabilization of the present system.