Convective heat transfer prediction for an axisymmetric jet impinging onto a flat plate with an improved k- model

Purpose - This paper aims to provide improvements to the newest version of the k- turbulence model of Wilcox for convective heat transfer prediction in turbulent axisymmetric jets impinging onto a flat plate.Design methodology approach - Improvements to the heat transfer prediction in the impingement zone are obtained using the stagnation flow parameter of Goldberg and the vortex stretching parameter of Wilcox. The third invariant of the strain rate tensor in the form of Shih et al. and the blending function of Menter are applied in order make negligible the influence of the impingement modifications in the benchmark flows for turbulence models. Further, it is demonstrated that for two-dimensional jets impinging onto a flat plate the stagnation region Nusselt number predicted by the original k- model is in good agreement with direct numerical simulation (DNS) and experimental data. Also for two-dimensional jets, the proposed modification is deactivated.Findings - The proposed modification has been applied to improve the convective heat transfer predictions in the stagnation flow regions of axisymmetric jets impinging onto a flat plate with nozzle-plate distances H D = 2, 6, 10 and Reynolds numbers Re = 23,000 and 70,000. Comparison of the predicted and experimental mean and fluctuating velocity profiles is performed. The heat transfer rates along a flat plate are compared to experimental data. Significant improvements are obtained with respect to the original k- model.Originality value - The proposed modification is simple and can be added to the k- model without causing stability problems in the computations.