Assessment of Refined RANS Models against Large Eddy Simulation and Experimental Data in the Investigation of Ribbed Passages with Passive Heat

Rough surfaces are widely used to enhance convective heat transfer by the promotion of higher turbulence levels. The present article reports simulations of the flow and heat transfer in a 2-D rib-roughened passage using a number of advanced Reynolds-averaged Navier-Stokes (RANS) turbulence models including eddy-viscosity models (EVM) and a Reynolds stress model (RSM). Large eddy simulation (LES) is also conducted and results are compared against experimental measurements. In addition, the effects of rib thermal boundary condition on heat transfer are also investigated. In the present work, the blockage ratio of the transversely mounted rectangular ribs is 10% and the rib pitch-to-height ratio of 9 is selected. The Reynolds number, based on the channel bulk velocity and hydraulic diameter, is 30,000. The RANS-based turbulence models investigated here are the k-ω-SST, the v2-f, the ϕ-f, and the elliptic blending RSM. All computations are undertaken using the commercial and industrial CFD codes STAR-CD and Code_Saturne, respectively. Of all the models, the LES predictions were found to be in the best agreement with the experimental data, while the k-ω-SST and EB-RSM returned the least accurate results.