EFFECTS OF VARIABLE VISCOSITY AND DENSITY MAXIMUM ON THE ONSET OF DARCY-BENARD CONVECTION USING A THERMAL NONEQUILIBRIUM MODEL

摘要

The effects of the temperature-dependent viscosity and density maximum on the criterion for the onset of convection in a horizontal porous layer are investigated when the solid and fluid phases are not in local thermal equilibrium. A two-field model that represents the fluid- and solid-phase temperature fields separately is used for the energy equation. The Galerkin method is used to obtain the eigenvalue equation, which is then solved numerically. It is noted that higher values of the viscosity number and the parameter representing the maximum-density property have the effect of delaying the onset of convection and reducing the size of convection cells. In addition, the influence of parameters representing the thermal nonequilibrium effects on convective instability is discussed in detail.