Eigenmode decomposition of the turbulent shear layer above a square rib

1D, 2D and fully 3D structural information is extracted from a large-eddy simulation of turbulent flow over a square rib, using 'Proper Orthogonal Decomposition'. In this paper, we focus on the shear layer separating at the leading edge and developing above and behind the top face of the flow obstacle. The two-point correlation tensor, required for the solution of the related eigenvalue problem, is provided from a large-eddy simulation for a Reynolds number of about 50 000 (based on obstacle height and incoming bulk velocity). The results indicate that the eigenmode decomposition is a very useful tool to extract organized structures even from very complex turbulent velocity fields at high Reynolds numbers. A significant amount of turbulent energy can still be captured by a relatively small number of modes. © 1993 Kluwer Academic Publishers.