Transition to turbulence in pipe flow

Abstract:
We here present an experimental investigation into the role and significance of travelling wave transients in turbulent pipe flow.
Turbulent flows in the range of 2000<Re<4500 are investigated and different criteria are employed to identify travelling wave transients. We investigate azimuthal symmetries as well as axial periodicity and the dynamics of low speed streaks.
Furthermore we provide evidence that turbulence has a finite lifetime and the dynamics evolve around a chaotic saddle in phase space.