The transition to turbulence in pipe and related shear flows has puzzled scientists for over a century. Here turbulence occurs despite the stability of the base flow and linear as well as weakly nonlinear methods have failed to predict transition.
Our recent experiments suggest that the turbulent state evolves around unstable travelling waves. These travelling waves have previously been identified as solutions to the Navier Stokes equations and they were suggested to provide the building blocks of the turbulent state. Using stereoscopic PIV we could for the first time visualize transients of such states in a turbulent flow.

Furthermore we present evidence that turbulence in pipe flow surprisingly only has a finite lifetime and that the turbulent dynamics evolve around a strange repellor rather than an attractor.