  The onset of shear flow turbulence is characterized by turbulent patches
bounded by regions of laminar flow. At low Reynolds numbers localized
turbulence relaminarises, raising the question of whether it is transient in
nature or it becomes sustained at a critical threshold. We present extensive
numerical simulations and a detailed statistical analysis of the data, in order
to shed light on the sources of the discrepancies present in the literature.
The results are in excellent quantitative agreement with recent experiments and
show that the turbulent lifetimes increase super-exponentially with Reynolds
number. In addition, we provide evidence for a lower bound below which there
are no meta-stable characteristics of the transients, i.e. the relaminarisation
process is no longer memoryless.
