Analysis of transient laminar convective heat transfer inside a circular duct

The present investigation is concerned with a direct numerical solution to a problem involving the transient laminar heat transfer inside a circular duct, taking into account a step change in either the wall temperature or the heat flux. The considered energy equation is parabolic with respect to time and the axial direction and elliptic with respect to the radial direction. The radial diffusion term is represented by means of a central difference form. In connection with stability considerations, a fully implicit formulation with respect to time was adopted. The obtained results are presented in a nunmber of graphs.