Fluid flow and heat transfer are computed through a rib-roughened duct of square cross-section. The staggered ribs are attached along the two opposite walls of the channel to augment heat transfer. Simulations are performed with an incompressible SIMPLEC finite volume collocated code. Five different versions of k- and k- turbulence models are employed. The molecular Prandtl number is 0.71 and the Reynolds number based on the bulk velocity and the height of the channel is 100000.
The predicted flow field and heat transfer show a relatively good agreement with the experimental results for different employed turbulence models, although the predicted flow field results are much better than the heat transfer results.
Employing a variable turbulent Prandtl number according to the Kays and Crawford relation shows only a small difference in the estimated turbulent heat transfer fluxes. The influence of constant turbulent Prandtl numbers ranging from 0.5 to 0.92 is also examined and it is found that it has a significant effect on the simulation results of the heat transfer.