Evolutionary geometry of Lagrangian structures in a transitional boundary layer
Evolutionary geometry of Lagrangian structures in a transitional boundary layer
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DOI：
10.1063/1.4944047
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发表时间：
2016-03
影响因子：
4.6
通讯作者：
Wenjie Zheng-;Yue Yang;Shiyi Chen
中科院分区：
文献类型：
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作者：
Wenjie Zheng-;Yue Yang;Shiyi Chen
我们报告了在马赫数为0.7的弱可压缩、空间演化过渡边界层中拉格朗日结构的几何研究。通过滑动窗口滤波器在一系列参考时间点从拉格朗日标量场中提取过渡过程中的拉格朗日结构。采用多尺度、多向几何分析方法对空间演化拉格朗日结构的几何特征进行了表征，包括从边界层厚度的一半到几个粘性长度尺度的不同尺度上的平均倾斜角和横扫角。在这里，倾斜角在向流和壁面法线方向的平面上，掠角在向流和展向方向的平面上。一般情况下，平均倾角随参考时间的增加而增大，掠角随参考时间的减小而减小。大尺度结构的角度变化小于小尺度结构。在过渡之前……
We report a geometric study of Lagrangian structures in a weakly compressible, spatially evolving transitional boundary layer at the Mach number 0.7. The Lagrangian structures in the transition process are extracted from the Lagrangian scalar field by a sliding window filter at a sequence of reference times. The multi-scale and multi-directional geometric analysis is applied to characterize the geometry of spatially evolving Lagrangian structures, including the averaged inclination and sweep angles at different scales ranging from one half of the boundary layer thickness to several viscous length scales. Here, the inclination angle is on the plane of the streamwise and wall-normal directions, and the sweep angle is on the plane of the streamwise and spanwise directions. In general, the averaged inclination angle is increased and the sweep angle is decreased with the reference time. The variation of the angles for large-scale structures is smaller than that for small-scale structures. Before the transition...