We present numerical simulations of the generation, evolution, and rad
io emission of superluminal components in relativistic jets. We perfor
m the fluid dynamical calculations using a relativistic time-dependent
code based on a high-resolution shock-capturing;scheme, and then we c
alculate the radio emission by integrating the transfer equations for
synchrotron radiation. These simulations show that a temporary increas
e in the flow velocity at the base of the jet produces a moving pertur
bation that contains both a forward and a reverse shock and is trailed
by a rarefaction. The perturbation appears in the simulated maps as a
region of enhanced emission moving downstream at a superluminal appar
ent velocity. Interactions of the perturbation with the underlying ste
ady jet result in changes in the internal brightness distribution of t
he superluminal component, which are manifested as low-level fluctuati
ons about the long-term evolution of both the apparent velocity and th
e exponential decay of the light curves.