Evolutionary geometry of Lagrangian structures in a transitional boundary layer

Zheng, Wenjie1; Yang, Yue1,2; Chen, Shiyi1,2,3

2016-03

10.1063/1.4944047

PHYSICS OF FLUIDS   影响因子和分区

1070-6631

1089-7666

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 multiscale 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, the averaged inclination and sweep angles are only slightly altered for all the scales. As the transition occurs, averaged inclination angles increase and sweep angles decrease rapidly for small-scale structures. In the late transitional stage, the averaged inclination angle of small-scale structures with 30 viscous length scales is approximately 42 degrees, and the averaged sweep angle in the logarithm law region is approximately 30 degrees. Additionally, the geometry of Lagrangian structures in transitional boundary layer flow is compared with that in the fully developed turbulent channel flow. (C) 2016 AIP Publishing LLC.

SCI ; EI

英语

其他

National Natural Science Foundation of China[11342011] ; National Natural Science Foundation of China[11472015] ; National Natural Science Foundation of China[11522215]

Mechanics ; Physics

Mechanics ; Physics, Fluids & Plasmas

WOS:000373600600049

AMER INST PHYSICS

20161302145352

Boundary layer flow ; Channel flow ; Geometry ; Lagrange multipliers

Fluid Flow, General:631.1 ; Mathematics:921

PHYSICS

Web of Science

1.Peking Univ, Coll Engn, State Key Lab Turbulence & Complex Syst, Beijing 100871, Peoples R China
2.Peking Univ, Ctr Appl Phys & Technol, Beijing 100871, Peoples R China
3.South Univ Sci & Technol China, Dept Mech & Aerosp Engn, Shenzhen 518055, Peoples R China

Zheng, Wenjie,Yang, Yue,Chen, Shiyi. Evolutionary geometry of Lagrangian structures in a transitional boundary layer[J]. PHYSICS OF FLUIDS,2016,28(3).

Zheng, Wenjie,Yang, Yue,&Chen, Shiyi.(2016).Evolutionary geometry of Lagrangian structures in a transitional boundary layer.PHYSICS OF FLUIDS,28(3).

Zheng, Wenjie,et al."Evolutionary geometry of Lagrangian structures in a transitional boundary layer".PHYSICS OF FLUIDS 28.3(2016).