Porosity Influence on Natural Convection Heat Transfer from a Heated Cylinder in a Square Porous Enclosure

In the present study, heat transfer in a square cavity filled by a fluid and a saturated porous media has been numerically analyzed to investigate the effect of void (ε) and thermal conductivity ratio (porous to fluid thermal conductivity ratio kr) of the material on flow and thermal field characteristics. A circular bar with a uniform heated surface is inserted into the middle of the cavity. The sides and upper walls of the cavity are maintained at a uniform cold temperature. Results are presented in terms of streamlines, isotherms, pressure distribution, average Nusselt number at several parameters values such Grashof number, material porosity, and thermal conductivity ratio. It is observed that these conditions have a significant effect on the flow and temperature field inside the cavity. It is found that porosity increment has a major influence for improving natural heat transfer and increasing average Nusselt number. In addition, the increment of thermal conductivity ratio of ten times leads to increase the average Nusselt number due to more heat transfer through the conduction the aid the natural convection to improve the overall heat transfer inside the cavity. In this work, Darcy number and Prandtl number are selected as 0.01 and 0.7, respectively. The analysis is accomplished for five porosity values, ɛ = 0.4, 0.5, 0.55, 0.6 and 0.65 and different values of Grashof numbers Gr and thermal conductivity ratio kr.