Computation Of Flow And Heat Transfer Through Channels With Periodic Dimple/Protrusion Walls Using Low-Reynolds Number Turbulence Models

Purpose This paper aims to predict turbulent flow and heat transfer through different channels with periodic dimple/protrusion walls. More specifically, the performance of various low-Re k-epsilon turbulence models in prediction of local heat transfer coefficient is evaluated. Design/methodology/approach Three low-Re number k-epsilon turbulence models (the zonal k-epsilon, the linear k-epsilon and the nonlinear k-epsilon) 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. Findings The numerical predictions indicate that the nonlinear k-epsilon model predicts a larger recirculation bubble inside the dimple with stronger impingement and upwash flow than the zonal and linear k-epsilon models. The heat transfer results show that the zonal k-epsilon model returns weak thermal predictions in all test cases in comparison to other turbulence models. Use of the linear k-epsilon model leads to improvement in heat transfer predictions inside the dimples and their back rim. However, the most accurate thermal predictions are obtained via the nonlinear k-epsilon model. As expected, the replacement of the algebraic length-scale correction term with the differential version improves the heat transfer predictions of both linear and nonlinear k-epsilon models. Originality/value The most reliable turbulence model of the current study (i.e. nonlinear k-epsilon model) 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).