DNS of turbulent heat transfer in channel flow with heat conduction in thesolid wall

The Direct Numerical Simulation (DNS) of the fully developed velocity and t emperature fields in the two-dimensional turbulent channel flow coupled wit h the unsteady conduction in the heated walls was carried out. Simulations were performed at constant friction Reynolds number 150 and Prandtl numbers between 0.71 and 7 considering the fluid temperature as a passive scalar T he obtained statistical quantities like root-mean-square temperature fluctu ations and turbulent heat fluxes were verified with existing DNS studies ob tained with ideal thermal boundary conditions. Results of the present study were compared to the findings of Polyakov (1974), who made a similar study with linearization of the fluid equations in the viscous sublayer that all owed analytical approach and results of Kasagi et al. (1989), who performed similar calculation with deterministic near-wall turbulence model and nume rical approach. The present DNS results pointed to the main weakness of the previous studies, which underestimated the values of the wall temperature fluctuations for the limiting cases of the ideal-isoflux boundary condition s. With the results of the present DNS it can be decided, which behavior ha s to be expected in a real fluid-solid system and which one of the limiting boundary conditions is valid for calculation, or whether more expensive co njugate heat transfer calculation is required.