Abstract
High-resolution particle-image velocimetry (PIV) measurements are made in the streamwise-wall-normal plane of turbulent channel flow at Reτ=566, 1184 and 1759, facilitating documentation of the population trends and core diameters of small-scale spanwise vortices. Swirling strength, an unambiguous vortex-identification criterion and hence a local marker of rotation, is used to extract small-scale spanwise vortex cores from the instantaneous velocity fields. Once the small-scale vortices are properly extracted from the PIV realizations, their characteristics are studied in detail. The present results indicate that the very-near-wall region (y < 0.1h) is densely populated by spanwise vortices with clockwise (negative) rotation. This behavior supports the notion that hairpin-like vortices are generated very close to the wall and grow into the outer layer as they advect downstream. In contrast, counterclockwise (positive) spanwise vortices are scarce in the very-near-wall region, but their presence steadily increases within the logarithmic layer presumably due to a localized generation mechanism. The average core diameter of negative spanwise vortices is found to be larger than the average diameter of positive vortices, with few positive vortices having core diameters exceeding 80y.
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Adrian, R. J., Christensen, K. T. and Liu, Z.-C., Analysis and interpretation of instantaneous turbulent velocity fields, Experiments in Fluids, 29 (2000a), 275–290.
Adrian, R. J., Meinhart, C. D. and Tomkins, C. D., Vortex organization in the outer region of the turbulent boundary layer, Journal of Fluid Mechanics, 422 (2000b), 1–54.
Chong, M. S., Perry, A. E. and Cantwell, B. J., A general classification of three-dimensional flow fields, Physics of Fluids A, 2 (1990), 765–777.
Christensen, K. T. and Adrian, R. J., Statistical evidence of hairpin vortex packets in wall turbulence, Journal of Fluid Mechanics, 431 (2001), 433–434.
Christensen, K. T., Soloff, S. M. and Adrian, R. J., PIV Sleuth — Integrated particle-image velocimetry interrogation/validation software, TAM Report, 943 (2000), University of Illinois at Urbana-Champaign, Urbana, Ill.
Christensen, K. T., Wu, Y., Adrian, R. J. and Lai, W., Statistical imprints of structure in wall turbulence, AIAA Paper 2004-1116 (2004).
Head, M. R. and Bandyopadhyay, P., New aspects of turbulent boundary-layer structure, Journal of Fluid Mechanics, 107 (1981), 297–338.
Jiménez, J., Wray, A. A., Saffman, P. G. and Rogallo, R. S., The structure of intense vorticity in isotropic turbulence, Journal of Fluid Mechanics, 255 (1993), 65–90.
Kim, K. C. and Adrian, R. J., Very large-scale motion in the outer layer, Physics of Fluids, 11 (1999), 417–422.
Kline, S. J. and Robinson, S. K., Quasi-coherent structures in the turbulent boundary layer. Part I: Status report on a community-wide summary of the data, Proceedings of Zaric Memorial Conference (Hemisphere), (1989), 200–217.
Marusic, I., On the role of large-scale structures in wall turbulence, Physics of Fluids, 13 (2001), 735–743.
Smith, C. R., A synthesized model of the near-wall behavior in turbulent boundary layers, Proceedings of the 8th Symposium on Turbulence, (1984), 299–325.
Theodorsen, T., Mechanisms of turbulence, Proceedings of the 2nd Midwestern Conference on Fluid Mechanics, (1952), 1–19.
Tomkins, C. D. and Adrian, R. J., Spanwise structure and scale growth in turbulent boundary layers, Journal of Fluid Mechanics, 490 (2003), 37–74.
Wu, Y., Spatial Characteristics of Outer-Layer Vortex Organization in Turbulent Channel Flow, (2004), M. S. Thesis, Department of Mechanical Engineering, The University of New Mexico, Albuquerque, NM.,
Zhou, J., Adrian, R. J., Balachandar, S. and Kendall, T. M., Mechanisms for generating coherent packets of hairpin vortices in channel flow, Journal of Fluid Mechanics, 387 (1999), 353–396.
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Kenneth T. Christensen: He received an M.S. in Mechanical Engineering in 1996 from Caltech and a Ph.D. in Theoretical and Applied Mechanics in 2001 from the University of Illinois at Urbana-Champaign. He was an assistant professor of Mechanical Engineering at the University of New Mexico prior to his current position as an assistant professor in the Theoretical and Applied Mechanics Department at the University of Illinois at Urbana-Champaign. His research interests include turbulence, microscale flows, cardiovascular fluid dynamics, multiphase flows and advanced experimental methods.
Yanhua Wu: He received an M.S. in Mechanical Engineering in 2004 from the University of New Mexico and is currently a Ph.D. student in the Theoretical and Applied Mechanics Department at the University of Illinois at Urbana-Champaign. His research interests include the effect of roughness and straining on the structure of wall turbulence and advanced experimental methods.
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Christensen, K.T., Wu, Y. Visualization and characterization of small-scale spanwise vortices in turbulent channel flow. J Vis 8, 177–185 (2005). https://doi.org/10.1007/BF03181661
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DOI: https://doi.org/10.1007/BF03181661