S0506-1-5 乱流プラントル数に及ぼす圧力勾配-速度相関の影響([0506-1]乱流における運動量,熱,物質の輸送現象(1))

抄録

The similarity between turbulent heat transfer and Reynolds stress is investigated using the equations written in Lagrange description. The correlation between pressure gradient fluctuation in the flow direction and wall-normal velocity [term (B)] depress the Reynolds stress, which makes the turbulent Prandtl number Prt less than unity. Using the database of trajectories of fluid particles calculated by DNS, an algebraic equation was derived to correlate the term (B) to the discrepancy between average velocity and temperature distribution. The change of Prt with regard to (B) was estimated based on the equation. The slight decrease of (B) causes the dramatic reduction of Prt near the channel center. As (B) is further decreased, the range of Prt reduction extends to the smaller y, while the change of Prt in y^+<60 is hardly recognized. The pressure gradient-wall normal velocity correlation has a strong influence on the dissimilarity in the log-law region of y^+>60.