  The non-equilibrium structural and dynamical properties of a semiflexible
polymer confined in a cylindrical microchannel and exposed to a Poiseuille flow
is studied by mesoscale hydrodynamic simulations. For a polymer with a length
half of its persistence length, large variations in orientation and
conformations are found as a function of radial distance and flow strength. In
particular, the polymer exhibits U-shaped conformations near the channel
center. Hydrodynamic interactions lead to strong cross-streamline migration.
Outward migration is governed by the polymer orientation and the corresponding
anisotropy in its diffusivity. Strong tumbling motion is observed, with a
tumbling time which exhibits the same dependence on Peclet number as a polymer
in shear flow.
