Kashyap Pavan V, Duguet Yohann, Dauchot Olivier
LIMSI-CNRS, UPR 3251, Université Paris-Saclay, 91405 Orsay, France.
Gulliver, ESPCI-CNRS, 10 Rue Vauquelin, 75005 Paris, France.
Entropy (Basel). 2020 Sep 8;22(9):1001. doi: 10.3390/e22091001.
The transitional regime of plane channel flow is investigated above the transitional point below which turbulence is not sustained, using direct numerical simulation in large domains. Statistics of laminar-turbulent spatio-temporal intermittency are reported. The geometry of the pattern is first characterized, including statistics for the angles of the laminar-turbulent stripes observed in this regime, with a comparison to experiments. High-order statistics of the local and instantaneous bulk velocity, wall shear stress and turbulent kinetic energy are then provided. The distributions of the two former quantities have non-trivial shapes, characterized by a large kurtosis and/or skewness. Interestingly, we observe a strong linear correlation between their kurtosis and their skewness squared, which is usually reported at much higher Reynolds number in the fully turbulent regime.
利用大区域内的直接数值模拟，研究了平面通道流在低于湍流无法持续的转捩点之上的转捩区。报告了层流 - 湍流时空间歇性的统计数据。首先对模式的几何形状进行了表征，包括该区域中层流 - 湍流条纹角度的统计数据，并与实验进行了比较。然后给出了局部和瞬时体速度、壁面剪应力和湍动能的高阶统计量。前两个量的分布具有非平凡的形状，其特征是具有较大的峰度和/或偏度。有趣的是，我们观察到它们的峰度和偏度平方之间存在很强的线性相关性，这种相关性通常在完全湍流状态下更高的雷诺数时才会被报道。
