熱的壁面境界条件が異なる非圧縮性チャネル乱流の数値解析(流体工学,流体機械)

The effects of the different thermal wall boundary conditions on the turbulence statistics are investigated using direct numerical simulation (DNS) of the incompressible turbulent channel flow with passive scalar transport. The flow between isothermal walls with same temperature (Case 1), the flow between isothermal walls with a temperature difference (Case 2), and the flow between isothermal and adiabatic walls (Case 3) are considered. The simulations are carried out on the flow with Reynolds numbers based on the channel half-width and wall friction velocity of 150 and 300, and with Prandtl number of 0.72. The present DNS shows that the absolute value of correlation coefficient between velocity and temperature fluctuations near the adiabatic wall (Case 3) is much smaller than those of Cases 1 and 2. It is shown that turbulent Prandtl number varies linearly with the square of wall unit very close to the adiabatic wall. In addition, the budgets with respect to the temperature variance, its dissipation rate, and turbulent heat fluxes near the adiabatic wall are clarified.