Toward the development of an algebraic turbulent heat flux model with the aid of les data

In order to derive a possible direction for improvements of an algebraic heat flux model, a priori explorations were attempted by processing the LES data presently performed under various flow and heat transfer conditions including shear-free boundaries. The present calibration has elucidated that the turbulent heat flux vectors obtainable from the simple GGDH hardly align with the simulation results in wall-shear flows with a wall normal temperature gradient of fluids at Pr ≥ 0.71. However, the GGDH returns a quite reasonable approximation for heat flux vectors in shear-free flow regions and/or lower Pr fluid cases. In the former flow cases, it has been found that a further introduction of a tensor expression, consisting of quadratic products of the Reynolds stress tensor, into the gradient diffusion model may improve the predictive performance.