Computation of flow and heat transfer in two-pass channels with 60 deg ribs

Numerical predictions of three-dimensional flow and heat transfer are presented for a two-pass square channel with and without 60 deg angled parallel ribs. Square sectioned ribs were employed along one side surface. The rib height-to-hydraulic diameter ratio (e/D-h) is 0.125 and the rib pitch-to-height ratio (P/e) is 10. the computation results were compared with the experimental data of Ekkad and Han [1] at a Reynolds number (Re) of 30,000. A multi-block numerical method was used with a chimera domain decomposition technique. The finite analytic method solved the Reynolds-Averaged Navier Stokes equation in conjunction with a near-wall second-order Reynolds stress (second-moments) closure model, and a two-layer k-epsilon isotropic eddy viscosity model. Comparing the second-moment and two-layer calculation with the experimental data clearly demonstrated that the angled rib turbulators and the 180 sharp turn of the channel produced strong non-isotropic turbulence and heat fluxes, which significantly affected the flow fields and heat transfer coefficients. The near-wall second-moment closure model provides an improved heat transfer prediction in comparsion with the k-epsilon model.