Investigation of the log region structure in wall bounded turbulence

Abstract

Multiple plane stereo PIV results and data from a rake of ten hot-wire probes are used to investigate the largest scale structures in the logarithmic region of a zero-pressure-gradient turbulent boundary layer. Studies over the past few years have reported that wall-parallel plane PIV vector fields are dominated by long meandering stripes of positive and negative u fluctuation. Such features alternate in the spanwise direction and carry a large proportion of the Raynolds shear stress in the outer regions [7, 21]. The size of these features appears to scale well with outer variables. A pronounced vortical structure is noted clustered about the elongated regions of momentum deficit in arrangem..