TY - JOUR
T1 - Analysis of conditional statistics obtained near the turbulent/non-turbulent interface of turbulent boundary layers
AU - Ishihara, Takashi
AU - Ogasawara, Hiroki
AU - Hunt, Julian C.R.
N1 - Funding Information:
This work was supported partly by Grant-in-Aids for Scientific Research (C) 23560194 from the Japan Society for the Promotion of Science, and also by JST , CREST . The computations were carried out on the Earth Simulator and on the FX1 system at the Information Technology Center of Nagoya University.
Publisher Copyright:
© 2014 The Authors.
PY - 2015/2/1
Y1 - 2015/2/1
N2 - Direct numerical simulations of turbulent boundary layers (TBL) along a flat plate are used to study the properties of turbulent/non-turbulent (T/NT) interface of the TBL. The values of the momentum-thickness-based Reynolds numbers, Reθ, used for this study, are 500-2200. Analysis of the conditional statistics near the interface of the TBL shows that there are a small peak in the spanwise vorticity, and an associated small jump in streamwise velocity. It is shown that the interfacial layer has an inertia-viscous double structure which consists of a turbulent sublayer with a thickness of the order of the Taylor micro-scale and its outer boundary with a thickness of the order of the Kolmogorov length scale. The velocity jump near the T/NT interface of the TBL is of the order of the rms value of velocity fluctuations near the interface. Conditional cross correlations of the streamwise or the wall-normal velocity fluctuations change sharply across the interface, which are consistent with the blocking mechanism of the interface.
AB - Direct numerical simulations of turbulent boundary layers (TBL) along a flat plate are used to study the properties of turbulent/non-turbulent (T/NT) interface of the TBL. The values of the momentum-thickness-based Reynolds numbers, Reθ, used for this study, are 500-2200. Analysis of the conditional statistics near the interface of the TBL shows that there are a small peak in the spanwise vorticity, and an associated small jump in streamwise velocity. It is shown that the interfacial layer has an inertia-viscous double structure which consists of a turbulent sublayer with a thickness of the order of the Taylor micro-scale and its outer boundary with a thickness of the order of the Kolmogorov length scale. The velocity jump near the T/NT interface of the TBL is of the order of the rms value of velocity fluctuations near the interface. Conditional cross correlations of the streamwise or the wall-normal velocity fluctuations change sharply across the interface, which are consistent with the blocking mechanism of the interface.
KW - Blocking mechanism
KW - Conditional statistics
KW - Turbulent boundary layer
KW - Turbulent/non-turbulent interface
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U2 - 10.1016/j.jfluidstructs.2014.10.008
DO - 10.1016/j.jfluidstructs.2014.10.008
M3 - Article
AN - SCOPUS:84925018126
SN - 0889-9746
VL - 53
SP - 50
EP - 57
JO - Journal of Fluids and Structures
JF - Journal of Fluids and Structures
ER -