CONJUGATE FREE-CONVECTION FROM A CIRCULAR-CYLINDER IN A POROUS-MEDIUM

The purpose of this paper is to formulate and solve the problem of steady free convection from a horizontal circular cylinder with a heated core embedded in a fluid-saturated porous medium. The governing equations were solved numerically using an efficient finite-difference technique. The effects of various parameters entering in the problem are presented in tabular and graphical forms. The thermal conductivity ratios of the cylinder wall to the porous medium vary from 0.5 to infinity. The ratio of cylinder inner radius to outer radius was 0.2, 0.5 and 0.9. The results were compared with the exact solution for the extreme case of a non-conjugate problem. Approximate solutions for the average boundary temperature between cylinder and porous matrix and for the average Nusselt number are also found, and the results are confirmed by numerical computations. It may be remarked that the present analysis gives compact formulae to provide useful information on the temperature distribution and the heat transfer from a cylinder and may find wide applications in the field of various thermal technologies.