Mixed Convection About a Horizontal Cylinder in a Porous Medium Using the Thermal Non-equilibrium Model
Nawaf H. Saeid and Ioan Pop
Numerical study is carried out in the present paper for the mixed convection about a horizontal cylinder immersed in a fluid-saturated porous medium using thermally non-equilibrium model. Darcy law and boundary layer approximations are used in the mathematical formulations. The governing parameters of the present problem are the ratio of Rayleigh number to Péclet number (Ra/Pe), the heat transfer coefficient parameter (H) and the porosity scaled thermal conductivity ratio parameter (Kr). The Keller box finite difference numerical method is used to solve the governing equations for forced, aiding and opposing mixed convection flows. The numerical results for the forced convection are presented for the local as well as average Nusselt numbers for fluid, solid and total values with different values of H and Kr. The effects of H and Kr on the variation of total average Nusselt number (Nut/Pe)against Ra/Pe are presented in details for both aiding and opposing mixed convection within the limitations of the boundary layer approximations. It is found for all the modes that the calculated values of Nut/Pe using thermally equilibrium model is the maximum possible values and these values are overestimated the convective heat transfer from the cylinder surface to the porous medium with low heat transfer coefficient parameter and low porosity scaled thermal conductivity ratio parameter.