Development of secondary flow and convective heat transfer in isothermal/iso-flux rectangular ducts rotating about a parallel axis

The present study investigates rotation-induced secondary flow and mixed co nvection heat transfer in the entrance region of rectangular ducts rotating about a parallel axis. Boussinesq approximation is invoked to take into ac count the centrifugal buoyancy. Mechanisms of the secondary vortex developm ent in ducts of isothermal or iso-flux walls are explored by a vorticity tr ansport analysis. Numerical solutions of the parabolized velocity-vorticity formulation of Navier-Stokes/Boussinesq systems are used to corroborate th e above theoretical analysis and provide evidence for the relevance of axia l variation of transport rates to the evolution of the secondary vortices. The present results also reveal that the rotational effect in an iso-flux d uct is more significant than that in an isothermal flux. In a fully develop ed flow region, the iso-Bus case can still retain a secondary vortex effect , while the effect vanishes in isothermal ducts. (C) 1998 Elsevier Science Ltd. All rights reserved.