Flow separation characterisation of a forward facing step immersed in a turbulent boundary layer

Flow separation experiments are conducted in two facilities using particle image velocimetry (PIV) and pressure tappings over a wide Reynolds number range for a forward facing step immersed in a turbulent boundary layer. Bluff body flow is observed with the fixed separation point located at the leading edge of the model. The recirculation region dimensions are characterised over the entire Reynolds number range using the PIV technique. Pressure tappings provide insight into the surface pressure distribution in a recirculation region. The mechanisms affecting the reattachment distance, X_L, namely the turbulent mixing within the boundary layer and the velocity deficit in the boundary layer are commented on.