ABSTRACT
The turbulence in two boundary layer regions in an open channel flow was investigated in this paper. The 5 m long flume was divided into 4 identical pools along its length, each pool separated by a trash rack composed of two regular grids. Tomographic Particle Image Velocimetry (TPIV) was used to measure the flow field. Two regions in the third pool downstream were considered, one at x/L=0.5 and the other x/L=0.85, where x is the streamwise coordinate and L the pool length. Ejections (Q2) and sweeps (Q4) were identified as were coherent vortices in the 3D flow field. The TPIV data yield allowed for the statistical analysis of the Reynolds stress distribution through the boundary layer along with the distribution of the turbulent energy dissipation. The turbulence properties of the flows were analysed and characterised by the location and by the turbulence in the free stream produced by the grids.
