DOI: 10.1615/TSFP3
A STUDY OF THE SURFACE HEAT-FLUX FLUCTUATIONS THROUGH DNS OF TURBULENT HEAT TRANSFER IN A CHANNEL FLOW
ABSTRAKT
In the present study, direct numerical simulation (DNS, hereafter) of turbulent heat transfer in a channel flow has been carried out in order to investigate the characteristics of the surface heat-flux fluctuations. The Reynolds numbers based on the friction velocity and the channel half width are 180, 395 and 640, and the molecular Prandtl numbers are 0.025 and 0.71. It is found that the large-scale structures exist even in the surface heat-flux fluctuations for both of the Prandtl numbers at high Reynolds number, which are essentially associated with large-scale motions for the thermal field existing in the outer layer. In addition, it is shown that the surface heat-flux fluctuations for the Prandtl number of Pr = 0.71 are mostly similar to the streamwise wall shear-stress fluctuations, but there exists the noticeable dissimilarity in the large positive and negative fluctuations.