RIGOROUS FORMULATION OF 2-EQUATION HEAT-TRANSFER MODEL OF TURBULENCE USING DIRECT SIMULATIONS

A rigorous hue-equation heat transfer model has been constructed with the aid of the most up-to-date direct numerical simulation (DNS) data for wall turbulence with heat transfer. The DNS data indicate that the near-wall profile of the dissipation rate, epsilon(t), for the temper ature variance, k(t) (= (t(2)) over bar/2), is completely different fr om the existing model predictions. In this study, we performed a criti cal assessment of existing epsilon(t) and <(epsilon)over tilde>(t) equ ations for both two-equation and second-order closure models. Based on these assessments, we propose a new dissipation rate equation for tem perature variance, taking into account all the budget terms in the exa ct epsilon(t) equation. Also the proposed a, equation is linked with a similarly refined k(t) equation to constitute a new hue-equation heat transfer model. Comparisons of the present model predictions with the DNS data for a channel flow with heat transfer have shown excellent a greement for the profiles of k(t) and epsilon(t) themselves and of the budget in the k(t) and epsilon(t) equations. The model is also tested in turbulent boundary-layer flows with five different wad thermal con ditions. Agreement with the experimental data is quite satisfactory.