Statistics of the turbulent/non-turbulent interface in a spatially developing mixing layer
Statistics of the turbulent/non-turbulent interface in a spatially developing mixing layer
复制标题
空间发展混合层中湍流/非湍流界面的统计
DOI：
10.1080/14685248.2014.919394
复制
发表时间：
2014
影响因子：
1.9
通讯作者：
F. Bisetti
中科院分区：
文献类型：
--
作者：
A. Attili;Juan C Cristancho;F. Bisetti
在空间发展的湍流混合层的直接数值模拟中，分析了将内部湍流区域与外部无旋转流体分开的薄界面。涡度阈值被定义为检测将湍流与流动的非湍流区域分开的界面，并计算以距该界面的距离为条件的统计数据。速度的条件统计与文献中提供的其他自由剪切流（例如湍流射流和尾流）的结果非常一致。此外，还对界面附近的无源标量场进行了分析。结果表明，标量在界面处存在跳跃，甚至比观察到的速度更强。之前在高施密特数 (Sc) 的情况下观察到标量的强烈跳跃。在本研究中，对于 Sc ≈ 1 的标量观察到如此强烈的跳跃。给出了动能和标量耗散的条件统计。虽然动能耗散在远离界面处具有最大值，但标量耗散的特点是在非常靠近界面处有一个强峰值。最后，结果表明，界面的几何特征与低压等值面可视化的相对较大尺度的结构相关。
The thin interface separating the inner turbulent region from the outer irrotational fluid is analysed in a direct numerical simulation of a spatially developing turbulent mixing layer. A vorticity threshold is defined to detect the interface separating the turbulent from the non-turbulent regions of the flow, and to calculate statistics conditioned on the distance from this interface. The conditional statistics for velocity are in remarkable agreement with the results for other free shear flows available in the literature, such as turbulent jets and wakes. In addition, an analysis of the passive scalar field in the vicinity of the interface is presented. It is shown that the scalar has a jump at the interface, even stronger than that observed for velocity. The strong jump for the scalar has been observed before in the case of high Schmidt number (Sc). In the present study, such a strong jump is observed for a scalar with Sc ≈ 1. Conditional statistics of kinetic energy and scalar dissipation are presented. While the kinetic energy dissipation has its maximum far from the interface, the scalar dissipation is characterised by a strong peak very close to the interface. Finally, it is shown that the geometric features of the interfaces correlate with relatively large scale structures as visualised by low-pressure isosurfaces.