FLOW STRUCTURES AND HEAT USING HYBRID RANS-LES METHODS OF STRUCTURED SURFACES

Flow structures and heat transfer of turbulent flow over a single dimple placed at the lower wall in a narrow channel at Reynolds number Re_D=42000 and Re_D=105000 for Prandtl number Pr=0.71 and Pr=3 have been analyzed using large eddy simulation (LES) and improved delayed detached eddy simulation with improved wall modeling capability (IDDES) of the 2011 version in OpenFOAM. Based on the simulations of the turbulent channel flow up to Re_tau=2400, the LES and IDDES approach implemented in OpenFOAM are validated and needed mesh resolutions are determined. The heat transfer rates and the skin-friction factors of the IDDES are consistent with empirical correlations whereas LES show large differences for higher Reynolds number using moderate grid sizes. The mean values as well as vortex structures and secondary flow structures using a spherical dimple have been analyzed and evaluated using experimental data.