Generic bluff bodies with undetermined separation location

The parameters governing forced attachment of flow to a flat, inclined surface, were determined by Nishri1. The addition of convex curvature is investigated presently using the circular cylinder as a model. In both flows the forcing consisted of two-dimensional, periodic oscillations emanating from a narrow slot. Naturally the flow separates from the surface of a smooth circular cylinder around 70° from the leading stagnation point when the Reynolds number is approximately 40,000. Periodic excitation from a slot located some 40° further downstream from the natural separation location altered very significantly the pressure distribution on that surface. On the opposite side of the cylinder neither the location of separation on the opposite side nor the pressure distribution was substantially affected, but a major change in the base pressure was observed. The cylinder started to lift and the typical vortex shedding from the cylinder was altered if not entirely eliminated. Experiments were carried out using both pressure measurements and particle image velocimetry (PIV). Numerical simulations were also carried out using an unstructured mesh finite element method with dynamic and constant coefficient Smagorinsky large eddy simulation (LES) turbulence models.