DOI: 10.1615/TSFP4
ASYMMETRIC TEMPORAL CROSS-CORRELATION FUNCTIONS IN TURBULENT SHEAR FLOWS
要約
Spatio-temporal cross-correlations between the turbulent velocity components in streamwise and wall-normal directions are investigated in an effort to identify effects due to non-normal amplification or lift up. The temporal cross-correlation between the downstream and normal velocity component shows a characteristic asymmetry related to the interplay between the streamwise streaks and pairs of streamwise vortices. Positive values of the asymmetry function Q > 0 implies that the shear flow is dominated by the no-normal lift-up of streamwise streaks by pairs of streamwise vortices. Q < 0 is found for regions in the shear flow where nonlinear convective effects dominate. This systematic variation of the asymmetry can be used to separate different layers in turbulent shear flows.