How does flow in a pipe become turbulent?
Bruno  Eckhardt
 University of Marburg


The routes to turbulence in many flows comprise series of transitions that introduce more and more temporal and spatial variations until the spatially and temporally disordered state we call turbulent is obtained.
Flow in a pipe does not fit into this scheme, as theory and experiment do not show any sharp transitions. Building on experience in dynamical systems we have proposed a scenario that involves certain types of waves and a strange saddle. This model is in good agreement with experiments and numerical simulations.