  Solar prominences are subject to all kinds of perturbations during their
lifetime, and frequently demonstrate oscillations. The study of prominence
oscillations provides an alternative way to investigate their internal magnetic
and thermal structures as the oscillation characteristics depend on their
interplay with the solar corona. Prominence oscillations can be classified into
longitudinal and transverse types. We perform three-dimensional ideal
magnetohydrodynamic simulations of prominence oscillations along a magnetic
flux rope, with the aim to compare the oscillation periods with those predicted
by various simplified models and to examine the restoring force. We find that
the longitudinal oscillation has a period of about 49 minutes, which is in
accordance with the pendulum model where the field-ligned component of gravity
serves as the restoring force. In contrast, the horizontal transverse
oscillation has a period of about 10 minutes and the vertical transverse
oscillation has a period of about 14 minutes, and both of them can be nicely
fitted with a two-dimensional slab model. We also find that the magnetic
tension force dominates most of the time in transverse oscillations, except for
the first minute when magnetic pressure overwhelms.
