On the Dynamics of the Polygonal Satellite Vortices

This paper deals with the dynamics of polygonal shapes resulting from the symmetry breaking of hollow-vortex core in a shallow water layer produced by a rotating disk near the bottom within a stationary cylindrical container. These polygonal shapes are investigated through image analysis. It is found that a given polygon rotates at the frequency close to one–third of the corresponding disk frequency and the flow dynamics around the apexes of the polygon is characterized by a frequency which is close to one–third of the frequency of the given polygonal pattern. The results also suggest a possible resonance between the satellite vortices at the apexes of the patterns and the bulk flow.