Transient thermal boundary layers over rough surfaces

Abstract

The transient heat transfer convection in a turbulent boundary layer is theoretically and experimentally studied when a time-periodical step-wise heat flux is imposed upon a rough surface. In particular, the behavior of the displacement height for the thermal boundary layer and the validity of the Reynolds analogy are analyzed. The local boundary layer characteristics, friction velocity, friction temperature and the displacement heights for the velocity and the temperature profiles, are evaluated through the graphical method of Perry and Joubert (1963) [3]. The results indicate that the displacement heights assume very different values and that the Reynolds analogy hypothesis is satisfied.