Computation of flow and heat transfer through channels with periodic dimple/protrusion walls using low-Reynolds number turbulence models

Abstract

PurposeThis paper aims to predict turbulent flow and heat transfer through different channels with periodic dimple/protrusion walls. More specifically, the performance of various low-Rek-ε turbulence models in prediction of local heat transfer coefficient is evaluated.Design/methodology/approachThree low-Re numberk-εturbulence models (the zonalk-ε, the lineark-εand the nonlineark-ε) are used. Computations are performed for three geometries, namely, a channel with a single dimpled wall, a channel with double dimpled walls and a channel with a single dimple/protrusion wall. The predictions are obtained using an in house finite volume code.FindingsThe numerical predictions indicate that the nonlineark-εmodel predicts a larger recirculation bubble inside the dimple with stronger impingement and upwash flow than the zonal and lineark-εmodels. The heat transfer results show that the zonalk-εmodel returns weak thermal predictions in all test cases in comparison to other turbulence models. Use of the lineark-εmodel leads to improvement in heat transfer predictions inside the dimples and their back rim. However, the most accurate thermal predictions are obtained via the nonlineark-εmodel. As expected, the replacement of the algebraic length-scale correction term with the differential version improves the heat transfer predictions of both linear and nonlineark-εmodels.Originality/valueThe most reliable turbulence model of the current study (i.e. nonlineark-εmodel) may be used for design and optimization of various thermal systems using dimples for heat transfer enhancement (e.g. heat exchangers and internal cooling system of gas turbine blades).