Thermal Instability of a Walters (Model B) Elastico-Viscous Fluid in the Presence of Variable Gravity Field and Rotation in Porous Medium

The problem of thermal instability of a Waltersʹ (model Bʹ) viscoelastic fluid in a porous medium is considered in the presence of a variable gravity field and rotation. It is found that the principle of exchange of stabilities is valid under certain conditions. For stationary convection, the Waltersʹ (model Bʹ) elastico-viscous fluid behaves like a Newtonian fluid. It is found that rotation has stabilizing effect as gravity increases upward and a destabilizing effect as gravity decreases upward, the medium permeability has stabilizing/destabilizing effects depending on the rotation parameter, gravity is considered to be increasing upward from its value g (i.e. A > 0). The effects of rotation and the medium permeability on thermal instability have also been shown graphically. The sufficient conditions for the non-existence of overstability are also obtained.