Add to ORKGThe experimental numerical simulations and experiments show the influence of geometry, surface boundary conditions, and Reynolds number on the occurrence of recirculation areas and on the flow structure developing in the process. Thus, purposeful control of this phenomenon, referred to as vortex breakdown, is possible. The good correlation between theory and experiment shows that these structure formation processes can be simulated using the finite difference method to solve the Navier-Stokes equations. Within the scope of this investigation, these are predominantly rotationally symmetrical flow structures. Any influence of different initial conditions on the steady final solutions was not to be observed within the scope of previous numeric...