Experimental and Numerical Investigation of 3-D Corner Separation in a Channel Flow with Adverse Pressure Gradient

Measurements of a plane one-sided diffuser with a variable expansion ratio are compared with RANS simulations at a Reynolds number of 51,000. Two-component PIV provides boundary conditions and a global validation of mean velocities. Profile PIV is applied to evaluate the wall shear stress and to measure turbulence statistics. Typical measurement uncertainties found in the buffer layer and in the separation region are below 1% for the mean and below 6% for the Reynolds stresses. Consistency of turbulence statistics is demonstrated by comparison with DNS. A first comparison with RANS simulations reveals significant differences between the eddy viscosity model and both Reynolds stress models, which predict qualitatively different developments of the vortex system over the corner separation.