• VARIABLE VISCOSITY EFFECTS ON PENETRATIVE CONVECTION IN SUPERPOSED FLUID AND POROUS LAYERS

Abstract

The variable viscosity effects on the onset of penetrative convection simulated via internal heating in a two-layer system in which a layer of fluid overlies and saturates a layer of porous medium is studied. The Beavers–Joseph slip condition is applied at the interface between the fluid and the porous layers and dependence of viscosity is assumed to be exponential. The boundaries are considered to be rigid, however permeable, and insulated to temperature perturbations. The eigen value problem is solved using a regular perturbation technique with wave number as a perturbation parameter. The ratio of fluid layer thickness to porous layer thickness, ζ, the viscosity parameter B, and the presence of volumetric internal heat source in fluid and/or porous layer play a decisive role on the stability characteristics of the system. It is observed that both stabilizing and destabilizing factors can be enhanced because of the simultaneous presence of a volumetric heat source and variable viscosity effects so that a more precise control (suppress or augment) of thermal convective instability in a layer of fluid or porous medium is possible.