  We perform direct numerical simulations to characterize the three-dimensional
wake dynamics of long inclined circular cylinders with inhomogeneous end
boundary conditions. Three Reynolds numbers, $\Rey=100$, 200 and 300 are
considered to reveal the roles of the intrinsic secondary instabilities and the
extrinsic end boundary effects in shaping the three-dimensional flows. At
$\Rey=100$, the end boundary effects are felt over the entire cylinder span by
inducing oblique vortex shedding, which is associated with stronger spanwise
flow in the wake than a parallel shedding. The Strouhal number of the oblique
shedding is related to that of the parallel shedding of straight cylinder by
the cosine law, considering the combined inclination angle and oblique angle.
At $\Rey=200$, the intrinsic secondary instability results in large-scale
vortex dislocation, precluding the propagation of the end boundary effects
towards further span. Nevertheless, for the inclined cases, oblique shedding is
still observed within limited span from the upstream end boundary. The oblique
vortices are related to the two-dimensional flow at $\Rey=200$ from the
viewpoint of cosine law. Further along the span, the oblique vortices
destabilizes with the formation of small-scale vortices, and the flow
transitions to the typical mode A* wake. At $\Rey=300$, the highly
three-dimensional flow near the end boundary creates disturbances that travel
along the cylinder span, creating vortex dislocations for cases with low
inclination angles. For high inclination angle, oblique vortex shedding is
again observed over the cylinder span, and is not disrupted by vortex
dislocations of either intrinsic or extrinsic causes.
