Sharif University of Technology, Azadi Ave, Tehran, 11365-11155, Iran
Department of Aerospace Engineering, Sharif University of Technology, Azadi Ave, Tehran, 14588-89694, Iran
Sharif University of Technology, Azadi Ave, Tehran, 14588-89694, Iran
Gerry E. Schneider
University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1, Canada
One prone strategy to enhance the thermal performance of heat exchangers is to use dimples on the surface of tubes. The produced dimples have a critical role in improving the thermal characteristics of the related heat exchanger. On the other hand, the accurate hydro-thermodynamic prediction of flow behavior through the dimpled tubes is necessary to achieve optimum design and excellent performance of the related heat exchanger. In this regard, numerical methods and computational fluid dynamic tools are widely used to predict the related
hydro-thermodynamic performances. Since the dimples promote the fluid flow regimes to fully turbulent flows with complex micron-sized vortices, the role of the utilized turbulence model becomes essential to achieving the most accurate numerical solution for the heat exchanger. The present study focuses on the turbulence model importance in accurately modeling turbulent flow through dimpled tubes. Furthermore, we investigate the influence of such accuracy in improving the corresponding thermal-fluid performance. In this regard, various Reynolds-averaged Navier-Stokes turbulence models are carefully examined for a wide range of applied Reynolds and Prandtl numbers. The achieved numerical solutions are evaluated against the experimental data. The present study shows that the k-ω SST and k-ε Realizable turbulence models provide reasonable accuracy with excellent computational efficiency. Consistent with the experimental data, these turbulence models predict about 79.6% increase in Nusselt number and 47.6% increase in the friction coefficient of the dimpled tube compared to those of an equivalent smooth tube.