A Study of Prandtl-number Effects on Turbulence Statistics with Different Reynolds Numbers through DNS of Turbulent Heat Transfer in a Channel Flow

摘要

Direct numerical simulation (DNS) of heat transfer in a channel flow through high spatial resolution has been carried out for Prandtl numbers Pr = 0.71 - 10 and Reynolds numbers Re{sub}τ = 180 and 395, where Re{sub}τ is based on the friction velocity and the channel half width. Reynolds-number dependences of the turbulence statistics and the instantaneous temperature fields are shown. The mean temperature within the logarithmic region for Pr = 10 at Re{sub}τ = 395 is lower than the one at Re{sub}τ = 180 because the thermal field is mixed well and becomes more homogeneous for higher Re{sub}τ. In addition, the budgets for the dissipation rate of the temperature variance are investigated to improve the turbulent heat flux model.