Natural convection in a vertical annulus boarded by an inner wall of finite thickness

A numerical investigation of natural convection heat transfer of a fluid in a vertical cylindrical annulus has been carried out. The inner wall, of finite thickness, is maintained at a higher temperature than the thin Outer wall. The top and the bottom walls are assumed insulated. A scale analysis is used to characterize the effect of the conductivity and thickness of the inner wall on the heat transfer. It is found that the numerical Solution of the full governing equations agree well with the scaling results. (C) 2004 Elsevier Science Ltd.