Convective heat and mass transfer to a cylinder sheathed by a porous layer

A systematic study of the flow, heat, and mass transfer around a cylinder sheathed by a second, porous cylinder and placed in a perpendicular turbulent air flow has been performed. The focus of the study was on applications in heat and mass transfer to a clothed human limb in outdoor conditions. Both numerical and experimental investigations have been carried out for the fluid flow. Dimensionless scaling rules have been presented for flow, heat and mass transfer as a function of the free stream Reynolds number, the Darcy number, the dimensionless air resistance of the porous layer, and the dimensionless distance between the outer and inner cylinder. The results have been compared to available data in the literature and to the present experiment. An empirical correlation, which concludes the most important results, has been proposed. The largest reduction of heat and mass transfer due to the sheath layer, compared to that for an uncovered cylinder, was found for intermediate values of the Reynolds number, the flow resistance of the sheath layer, and the thickness of the air gap between solid and sheath cylinder.