  Most stars in galactic disks are believed to be born as a member of star
clusters or associations. Star clusters formed in disks are disrupted due to
the tidal stripping and the evolution of star clusters themselves, and as a
results new stars are supplied to the galactic disks. We performed $N$-body
simulations of star clusters in galactic disks, in which both star clusters and
galactic disks are modeled as $N$-body ("live") systems, and as a consequence
the disks form transient and recurrent spiral arms. In such non-steady spiral
arms, star clusters migrate radially due to the interaction with spiral arms.
We found that the migration timescale is a few hundreds Myr and that the
angular momentum changes of star clusters are at most $\sim 50$% in 1 Gyr.
Radial migration of star clusters to the inner region of galaxies results in a
fast disruption of the star clusters because of a stronger tidal field in the
inner region of the galaxy. This effect is not negligible for the disruption
timescale of star clusters in galactic disks. Stars stripped from clusters form
tidal tails which spread over 1--2 kpc. While the spatial distribution of tidal
tails change in a complicated way due to the non-steady spiral arms, the
velocity distribution conserve well even if the tidal tails are located at a
few kpc from their parent clusters. Tidal tails of clusters in galactic disks
might be detected using velocity plots.
