Flow field around a circular obstacle emerging from an erosion scour hole.

The behavior of turbulent boundary layer over a flat bottom and a scour hole, in the presence of a cylindrical obstacle normal to the bottom has been investigated. This has been done through flow visualizations. The flow structures in the flat bottom and in the scour hole cases have been compared. The dominant features of the vortex structure in terms of the number of the principal vortices and critical lines have been taken as the main flow parameters. The flow fields, with different Reynolds numbers, have also been compared. The Poincare-Bendixon theorem, modified for a 3D body attached to a surface, has been verified by means of the flow visualizations. [ABSTRACT FROM AUTHOR]