TRPIV investigation of space-time correlation in turbulent flows over flat and wavy walls

doi:10.1007/s10409-014-0060-7

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	TRPIV investigation of space-time correlation in turbulent flows over flat and wavy walls
	Wang W; Guan XL; Jiang N(姜楠)
发表期刊	Acta Mechanica Sinica
	2014-08
卷号	30 期号:4 页码:468-479
摘要	The present experimental work is devoted to investigate a new space-time correlation model for the turbulent boundary layer over a flat and a wavy walls. A turbulent boundary layer flow at Re (theta) = 2 460 is measured by tomographic time-resolved particle image velocimetry (Tomo-TRPIV). The space-time correlations of instantaneous streamwise fluctuation velocity are calculated at 3 different wall-normal locations in logarithmic layer. It is found that the scales of coherent structure increase with moving far away from the wall. The growth of scales is a manifestation of the growth of prevalent coherent structures in the turbulent boundary layer like hairpin vortex or hairpin packets when they lift up. The resulting contours of the space-time correlation exhibit elliptic-like shapes rather than straight lines. It is suggested that, instead of Taylor hypothesis, the elliptic model of the space-time correlation is valid for the wallbounded turbulent flow over either a flat wall or a wavy wall. The elliptic iso-correlation curves have a uniform preferred orientation whose slope is determined by the convection velocity. The convection velocity derived from the space-time correlation represents the velocity at which the large-scale eddies carry small-scale eddies. The sweep velocity represents the distortions of the small-scale eddies and is intimately associated with the fluctuation velocity in the logarithmic layer of turbulent boundary layers. The nondimensionalized correlation curves confirm that the elliptic model is more proper for approximating the space-time correlation than Taylor hypothesis, because the latter can not embody the small-scale motions which have non-negligible distortions. A second flow over a wavy wall is also recorded using TRPIV. Due to the combined effect of shear layers and the adverse pressure gradient, the space-time correlation does not show an elliptic-like shape at some specific heights over the wavy wall, but in the outer region of the wavy wall-bounded flow, the elliptic model remains valid.
DOI	10.1007/s10409-014-0060-7
收录类别	SCI ; EI ; CSCD
语种	英语
WOS记录号	WOS:000340551700002
项目资助者	National Natural Science Foundation of China 11332006 11272233 National Key Basic Research Program 2012CB720101 Tianjin University Research and Innovation Foundation opening subjects of The State Key Laboratory of Nonlinear Mechanics (LNM), Institute of Mechanics, Chinese Academy of Sciences
论文分区	二类
引用统计	被引频次：11[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://dspace.imech.ac.cn/handle/311007/59161
专题	非线性力学国家重点实验室
推荐引用方式 GB/T 7714	Wang W,Guan XL,Jiang N. TRPIV investigation of space-time correlation in turbulent flows over flat and wavy walls[J]. Acta Mechanica Sinica,2014,30,4,:468-479.
APA	Wang W,Guan XL,&Jiang N.(2014).TRPIV investigation of space-time correlation in turbulent flows over flat and wavy walls.Acta Mechanica Sinica,30(4),468-479.
MLA	Wang W,et al."TRPIV investigation of space-time correlation in turbulent flows over flat and wavy walls".Acta Mechanica Sinica 30.4(2014):468-479.

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