Fluid flow and forced convection heat transfer around a solid cylinder wrapped with a porous ring

Convective heat transfer from cylinders embedded in porous media is important for many engineering applications. In the present study, flow-field and heat transfer around a cylinder embedded in a layer of homogenous porous media is investigated numerically. The range of Reynolds and Darcy numbers are chosen to be 1-40 and 1 x 10(-8)-1 x 10(-1), respectively. Volume averaged equations are used for modeling transport phenomena within the porous layer and conservation laws of mass, momentum, an energy are applied in the clear region. A comprehensive parametric study is carried out and effects of several parameters, such as porous layer thickness and permeability as well as the Darcy and Reynolds numbers on flow-field and heat transfer characteristics are studied. Finally an optimization process is conducted in order to determine the optimal thickness and porosity of the porous layer resulting in the lowest heat transfer from the cylinder. The numerical results indicate that, in the presence of a porous layer around the cylinder, the wake length increases with decreasing the Darcy number while the critical radius of insulation increases. (c) 2013 Elsevier Ltd. All rights reserved.