The effects of duct shape on the nusselt number

This article considers the effect of duct shape on the Nusselt number. In order to show the effects of duct shape on the Nusselt number, four illustrative examples are given: the heat transfer in a duct of rectangular cross-section, heat transfer in a duct of semicircular cross-section, the heat transfer in a duct of circular cross-section and heat transfer between two parallel plates. The method used in this paper is general and it can be applied al flows. It is not necessary to use thin plate analogy, first, the velocity distribution is obtained and then the temperature distribution is found. It is shown that the Nusselt numbers calculated for the four examples cited depend not only on duct shape but also on wall friction.