Akademik Veri Yönetim Sistemi
INTERNATIONAL JOURNAL OF THERMAL SCIENCES, cilt.43, sa.8, ss.725-732, 2004 (SCI-Expanded)
Unsteady convective heat transfer in turbulent pipe flow has been computationally investigated, by means of transient simulations, using different turbulence models. The transient analysis was preceded by a steady-state study, where no substantial differences in the performances of the considered two-equation turbulence models were observed. In the transient analysis, the main emphasis has been placed upon high Reynolds number, two-equation turbulence models, augmented by the wall-functions approach. Two-layer-zonal models, which do not utilize the wall-functions approach have also been considered for some cases. Step-like, pulse-like and sinusoidal perturbations of the flow rate at various Reynolds numbers have been analysed. Results have been compared with measurements. It has been observed that some features of the considered configurations could. be predicted. On the other hand, some aspects such as the delay of the transient response of the wall heat flux to the flow rate changes could not be predicted well. (C) 2004 Elsevier SAS. All rights reserved.