68th Annual Meeting of the APS Division of Fluid Dynamics (November 22, 2015 — November 24, 2015)

P0011: Hairpin-packed "turbulent spots" deep inside the fully-turbulent flat-plate boundary layer

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Authors

• Xiaohua Wu, Royal Military College of Canada
• James Wallace , University of Maryland
• Parviz Moin, Stanford University

DOI: https://doi.org/10.1103/APS.DFD.2015.GFM.P0011

Do turbulent spots observed in transitional region also exist deep inside the fully-turbulent flat-plate boundary layer? This is a thought-provoking question that has rarely been asked until this point.

Here, we provide evidence for the existence of turbulent "turbulent spots" in the log-region and below of the fully-turbulent flat-plate boundary layer over the momentum-thickness Reynolds number range from 2800 to 2900. The turbulent "turbulent spots" and the transitional "turbulent spots" are similar in the sense that structurally both are formed by chaotic and packed hairpin vortices.