  We present 3D hydrodynamic adiabatic simulations of a shock interacting with
a dense, elongated cloud. We compare how the nature of the interaction changes
with the filament's length and its orientation to the shock, and with the shock
Mach number and the density contrast of the filament. We then examine the
differences with respect to 3D spherical-cloud calculations. We find
significant differences in the morphology of the interaction when M=10 and
chi=100: in many cases 3 parallel rolls are formed, and spread further apart
with time, and periodic vortex shedding can occur off the ends of oblique
filaments. Sideways-on filaments are accelerated more quickly, and initially
lose mass more quickly than spherical clouds due to their greater surface area
to volume ratio. However, at late stages they lose mass more slowly, due to the
reduced relative speed between the filament and the postshock flow. The
acceleration and mixing timescales can vary by a factor of 2 as the filament
orientation changes. Oblique filaments can achieve transverse velocities up to
10% of the shock speed. Some aspects of our simulations are compared against
experimental and numerical work on rigid cylinders.
