Numerical study on the characteristics of flow and heat transfer around a porous elliptical cylinder with various ellipticity ratio

Porous media can be widely applied in the fields of chemical and energy industries, due to their high porosity and high thermal conductivity. In this study, the characteristics of flow and heat transfer around a porous elliptical cylinder placed in a channel are numerically investigated, considering several influencing factors, such as ellipticity ratio (x(2)/a(2)+y(2)/b(2)= 1, a/b), Darcy number (10(-6) <= Da <= 10(-3)), Reynolds number (10 <= Re <= 40), internal thermal intensity (Q = 10 W, 50 W). Both the Darcy-Brinkman-Forchheimer extended model and local thermal equilibrium (LTE) model are used to describe the thermal behaviors in the porous region. The effects of such factors on the vortex suppression, wake loss, and thermal enhancement are comprehensively analyzed. It is demonstrated that the higher Reynolds number in the channel results in the more extensive vortex length for the same Darcy number. Especially, when the Reynolds number exceeds 20 and the ellipticity is a/b = 1/4, the wake vortex is significantly suppressed and heat transfer is enhanced near the porous wake zone. In addition, the drag coefficient dramatically increases with decreasing ellipticity of the porous cylinder, and the mean Nusselt number near the porous region significantly increases as well. With an increasing Darcy number, the drag coefficient decreases and the vortex length is suppressed. Furthermore, the mean Nusselt number near the porous elliptical cylinder is enhanced as the increase of Darcy number and Reynolds number. This study could offer some insights into how porous media enhances the heat transfer in the channeling flow.