  Flexible filamentous beds interacting with a turbulent flow represent a
fundamental setting for many environmental phenomena, e.g., aquatic canopies in
marine current. Exploiting direct numerical simulations at high Reynolds number
where the canopy stems are modelled individually, we provide evidence on the
essential features of the honami/monami collective motion experienced by hairy
surfaces over a range of different flexibilities, i.e., Cauchy number. Our
findings clearly confirm that the collective motion is essentially driven by
fluid flow turbulence, with the canopy having in this respect a fully-passive
behavior. Instead, some features pertaining to the structural response turn out
to manifest in the motion of the individual canopy elements when focusing, in
particular, on the spanwise oscillation and/or on sufficiently small Cauchy
numbers.
