Computation of flow and heat transfer through rotating ribbed passages

Abstract

Abstract This study focuses on the computation of periodic flow and heat transfer through stationary and rotating ducts of square cross-section, with rib-roughened walls. Square-sectioned ribs, normal to the flow direction are employed along two opposite walls. Flow comparisons are presented for a duct under stationary and rotating conditions, with ribs in a staggered arrangement. The rib-height-to-diameter ratio is 0.1 and the rib-pitch-to-rib-height ratio is 10. Heat transfer comparisons are shown for a stationary duct with in-line ribs. The rib-height-to-diameter ratio is 0.0675 and the rib-pitch-to-rib-height ratio is 10. Body-fitted grids are employed and two zonal models of turbulence are tested; a k–ϵ with the 1-equation model of k transport across the near-wall regions and a low-Re version of the basic DSM model, in which in the near-wall region the dissipation rate, ϵ, is obtained from the wall distance. The numerical approach adopted leads to the efficient calculation of flows through ribbed ducts. Both models yield satisfactory mean flow predictions and the DSM is also able to reproduce most of the features of the turbulence field, under both stationary and rotating conditions. Though the computations of the coefficient of wall heat transfer are not as close to the data as the flow predictions, the DSM thermal computations are clearly superior to those of the k–ϵ/1-equation.