ON THE TOPOLOGICAL BIFURCATION OF FLOWS AROUND A ROTATING CIRCULAR-CYLINDER

Flow fields around a rotating circular cylinder in a uniform stream ar e computed using a low dimensional Galerkin method. Results show that the formation of a Fopple vortex pair behind a stationary circular cyl inder is caused by the structural instability in the vicinity of the s addle located at the rear of the cylinder. For rotating cylinder a bif urcation diagram with the consideration of two parameters, Reynolds nu mber Re and rotation parameter a, is built by a kinematic analysis of the steady flow fields.