Turbulent convection velocities in a turbulent boundary layer

Turbulent convection velocities in a turbulent boundary layer are of crucial importance for bringing together theory and experiment. In this study, we determine probability density functions ($pdf$s) of turbulent convection velocities per wavenumber $k_x$ --using a phase-spectral approach-- from time-resolved PIV measurements in a stream-wise wall-normal plane of a turbulent boundary layer at $Re_\tau\approx2700$. A field-of-view covering approximately $2\times0.5\delta$ with high spatial, $l^+=20$, and temporal resolution, $\Delta t^+= 0.7$, allows us to determine convection velocities for a range of different wall-normal locations ($y/\delta:0.02-0.47$; $y^+:60-1260$). The results indicate that the mode of the $pdf$s coincides with the local mean velocity and that there is a considerable spread around this mode. In the talk, a detailed description of turbulent convection velocities with wall-normal distance will be presented.