Experimental investigation of instantaneous local flow separation in a turbulent boundary layer at various Reynolds numbers

The effect of the Reynolds number on the mechanism of the formation of an instantaneous local flow separation that occurs in the near-wall region of a turbulent boundary layer is experimentally studied. The features of application of the high-speed planar PIV method with a high spatiotemporal resolution are discussed. Comparison of the measurement results obtained within a viscous sublayer of a turbulent boundary layer with the results of other studies showed the generality of the mechanism for the formation of an instantaneous local flow separation in the range of dynamic Reynolds number 207 ≤ Re τ ≤ 672.