PIV measurements of a Wake from a Rough Flat Plate*

The formation of wakes over smooth bodies has been extensively studied, however the same cannot be said for wakes that evolve from rough bodies. Surface roughness is known to greatly affect the behaviour of a turbulent boundary layer and the nature of the structures within. These rough turbulent boundary layers modify the formation of the wake and its spatial-temporal evolution. The present study used 2-component - 2-dimensional particle image velocimetry (2C-2D PIV) to measure the wake flow evolving from a smooth and rough flat plate with a blunt trailing edge in the LTRAC large horizontal water tunnel facility. Specifically, 2C-2D PIV was acquired in the near wake, in addition to the turbulent boundary layer at the trailing edge of the plate. The boundary layer was tripped after the semi-elliptical leading edge and developed over the flat plate with a free-stream velocity of 400 mm/s and Re_θ = 1.64×10⁸   at the leading edge. The surface was roughened using graded particles adhered to the surface. First and second order statistics of these measurements will be presented.