HRT

Abstract

Transition to turbulence in cylindrical pipe flow is still not a well understood phenomenon. However, Direct numerical simulation in pipes with periodic boundary conditions shares a lot of common features with recent experiments. Here we are interested in the structure of the laminar-turbulent boundary, the manifold in phase-space separating the initial conditions leading to turbulence from those who lead to quick relaminarisation. Depending on the symmetries of the problem, phase-space trajectories on this manifold approach transiently various travelling wave solutions sitting on it. We can study the implications of this on the transition problem for both short and long pipes.