Turbulent heat transfer in a two-pass cooling channel by several wall turbulence models

This study presents a computational study of turbulent heat transfer through two-pass square-duct channel flows with several different turbulence models that were developed to improve near-wall predictions. To evaluate the performance of the advanced wall function (the analytical wall-function: AWF), the results were compared with experimental data, those by a low-Reynolds-number k-ε model and a conventional wall function (the log-low based wall-function: LWF). Furthermore, the study extended to examining three more extended forms of the AWF. The duct used in this paper was a square duct of 50.8 mm side length (hydraulic diameter is 50.8 mm) and three Reynolds number cases were examined (30,000, 60,000 and 90,000). The LWF showed much lower Nusselt number levels in complex turbulent flow regions such as separation and reattachment zones, because the log-low employed in the model is impossible in such regions. On the other hand, the AWF proved its better performance over the LWF in the width of Reynolds number flow range. In addition, the extended forms of the AWF also showed improvements in the heat transfer predictions.