TRPIV investigation of space-time correlation in turbulent flows over flat and wavy walls
文献类型：期刊论文
| 作者 | Wang W; Guan XL; Jiang N(姜楠)
|
| 刊名 | Acta Mechanica Sinica
 |
| 出版日期 | 2014-08 |
| 卷号 | 30期号:4页码:468-479 |
| 中文摘要 | 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. |
| 分类号 | 二类 |
| 收录类别 | SCI ; EI ; CSCD |
| 语种 | 英语 |
| WOS记录号 | WOS:000340551700002 |
| 源URL | [http://dspace.imech.ac.cn/handle/311007/59161]  |
| 专题 | 力学研究所_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. |
入库方式： OAI收割
来源：力学研究所
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