Numerical Prediction of Flow and Heat Transfer in a Two-pass Square Channel with 90^° Ribs

Abstract

Numerical predictions of three-dimensional flow and heat transfer are presented for a two-pass square channel with ^° parallel ribs. Square sectioned ribs were employed along the 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 (1997) 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 (secondmoment) closure model, and a two-layer k − ε isotropic eddy viscosity model. Comparing the second-moment and two-layer calculations with the experimental data clearly demonstrated that the 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 comparison with the k − ε model.