  Practically all flows are turbulent in nature and contain some kind of
irregularly-shaped particles, e.g. dirt, pollen, or life forms such as bacteria
or insects. The effect of the particles on such flows and vice-versa are highly
non-trivial and are not completely understood, particularly when the particles
are finite-sized. Here we report an experimental study of millimetric fibers in
a strongly sheared turbulent flow. We find that the fibers show a preferred
orientation of $-0.38\pi \pm 0.05\pi$ ($-68 \pm 9^\circ$) with respect to the
mean flow direction in high-Reynolds number Taylor-Couette turbulence, for all
studied Reynolds numbers, fiber concentrations, and locations. Despite the
finite-size of the anisotropic particles, we can explain the preferential
alignment by using Jefferey's equation, which provides evidence of the benefit
of a simplified point-particle approach. Furthermore, the fiber angular
velocity is strongly intermittent, again indicative of point-particle-like
behavior in turbulence. Thus large anisotropic particles still can retain
signatures of the local flow despite classical spatial and temporal filtering
effects.

Fluid Dynamics