日本機械学会論文集
Online ISSN : 2187-9761
ISSN-L : 2187-9761
熱工学,内燃機関,動力エネルギーシステム
高レイノルズ数チャンネル乱流場の内層温度分布におけるプラントル数効果
猿渡 祥悟山本 義暢
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ジャーナル フリー

2014 年 80 巻 814 号 p. TEP0153

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Prandtl number (Pr) effects on characteristics of the thermal boundary layer were investigated by means of Direct Numerical Simulations (DNS) in high-Reynolds number turbulent channel flows. The molecular Pr conditions were changed from 0.71 to 25.0, and the Reynolds number based on the friction velocity and channel half-width was kept to 1000 in all cases. The mean temperature profiles were good agreements with Kader's empirical equations except for the case of Pr = 25.0. The thicknesses of thermal conduction sub-layer became thinner in proportion to a one third power of Pr. On the other hands, the peak wall-normal heights in temperature intensity became thinner in proportion to a one half power of Pr. In both thermal layers of the conduction and logarithmic, results of quadrant and Kullback-Leibler Divergence (KLD) analyses were shown analogous characteristics in all Pr cases. On the other hand, in the buffer layer, the contributions of sweep and ejection events on wall-normal turbulent heat flux and distribution of KLD were shown the different distributions between in cases of Pr = 0.71 and Pr = 5.0, 25.0.

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