Active chimney effect using heated porous layers: optimum heat transfer

摘要: The purpose of the present work is to treat numerically problem steady mixed convection that occurs in a vertical cylinder, opened at both ends and filled with succession three fluid saturated porous elements, namely partially duct. flow conditions fit classical Darcy-Brinkman model allowing analysing structure on overall domain. induced heat transfer, terms local average Nusselt numbers, discussed for various controlling parameters as medium permeability, Rayleigh Reynolds numbers. efficiency considered system improved by injection/suction matrices frontier. undertaken numerical exploration particularly highlighted two possible types flows, without recirculation, which principally depend regime. Thus, it especially shown recirculation zones appear some domain areas under specific conditions, obvious negative central velocity prevalence natural effects, i.e., turnoff swirls. These latter are more accentuated close obstacles weak permeability. Furthermore, when injection or suction considered, transfer increases reduces injection.