  We report the results of simulations of rigid colloidal helices suspended in
a shear flow, using dissipative particle dynamics for a coarse-grained
representation of the suspending fluid, as well as deterministic trajectories
of non-Brownian helices calculated from the resistance tensor derived under the
slender-body approximation. The shear flow produces nonuniform rotation of the
helices, similarly to other high aspect ratio particles, such that more
elongated helices spend more time aligned with the fluid velocity. We introduce
a geometric effective aspect ratio calculated directly from the helix geometry
and a dynamical effective aspect ratio derived from the trajectories of the
particles and find that the two effective aspect ratios are approximately equal
over the entire parameter range tested. We also describe observed transient
deflections of the helical axis into the vorticity direction that can occur
when the helix is rotating through the gradient direction and that depend on
the rotation of the helix about its axis.
