  Travelling-wave solutions are shown to bifurcate from relative periodic
orbits in plane Poiseuille flow at Re = 2000 in a saddle-node infinite period
bifurcation. These solutions consist in self-sustaining sinuous
quasi-streamwise streaks and quasi- streamwise vortices located in the bulk of
the flow. The lower branch travelling-wave solutions evolve into spanwise
localized states when the spanwise size Lz of the domain in which they are
computed is increased. On the contrary, upper branch of travelling-wave
solutions develop multiple streaks when Lz is increased. Upper branch
travelling-wave solutions can be continued into coherent solutions of the
filtered equations used in large-eddy simulations where they represent
turbulent coherent large-scale motions.
