  The transition to turbulence in a long, straight pipe is one of the
outstanding unresolved problems in classical Physics. It is well-established by
experiments that a finite amplitude disturbance is required to trigger the
transition to turbulence from laminar flow. Details of the processes involved
in the transition are mysterious and a full understanding of them remains
aloof. Here we take the novel approach of initiating the flow in a turbulent
state and then reducing the flow rate suddenly, a so-called quench, so that the
flow decays from turbulence. We use two distinct methods of driving the flow
and find that the dynamical processes involved in the decay, as well as the
fraction of the flow that remains turbulent, are qualitatively distinct for
each driving protocol.
