Axial vortex breakdown topology in the Vogel-Escudier flow

Vogel-Escudier flow is analyzed using three-dimensional numerical simulations, a flow inside a cylinder with a rotating endwall. The flow exhibits an axial vortex and serves as a model problem to study the axial vortex breakdown phenomenon. The breakdown of the axial vortex occurs at some critical values of Reynolds number ($Re$) and the aspect ratio of the cylinder. Apart from the vortex breakdown, the flow exhibits rich dynamics, which supports the appearance of rotating azimuthal waves when the symmetry of the flow breaks. The flow supports a single azimuthal mode at lower $Re$ but can support multiple azimuthal modes at higher $Re$. A map with the classification of the various flow states in the parameter space of the Reynolds number and the aspect ratio is proposed. The topology of these states is demarcated on the map. The flow states and the associated perturbations are analyzed and will be presented in detail.