Accuracy in evaluating heat transfer coefficient by RANS CFD simulations in a rectangular channel with high aspect ratio - Part 2: channel with ribbed walls

Abstract

In this paper, a Computational Fluid-Dynamics (CFD) analysis on heat transfer characteristic using Reynolds Averaged Navier-Stokes (RANS) equations on a rectangular channel with ribbed surfaces is presented. Several numerical simulations have been carried out on convective heat transfer of an air flow through a rectangular channel of 1:10 aspect ratio, 120 mm wide, 840 mm long, with 90° ribs. Ribs have a square cross section with 4 mm side and three different values of dimensionless pitch, namely, 10, 20 and 40. Results on convective global heat transfer coefficient, i.e., averaged over the whole channel, have been compared to experimental data obtained in a channel with the same geometry and boundary conditions. Agreement between numerical and experimental data is discussed for the three different pitches considered. As expected, comparisons show a decreasing reliability for increasing complexity. The aim of this work is to find a suitable configuration of a CFD model with RANS that will permit authors to apply it to the range of dimensionless pitches.