  We model the dynamical evolution of primordial black holes (BHs) in dense
star clusters using a simplified treatment of stellar dynamics in which the BHs
are assumed to remain concentrated in an inner core, completely decoupled from
the background stars. Dynamical interactions involving BH binaries are computed
exactly and are generated according to a Monte Carlo prescription. Recoil and
ejections lead to complete evaporation of the BH core on a timescale ~10^9 yr
for typical globular cluster parameters. Orbital decay driven by gravitational
radiation can make binaries merge and, in some cases, successive mergers can
lead to significant BH growth. Our highly simplified treatment of the cluster
dynamics allows us to study a large number of models and to compute statistical
distributions of outcomes, such as the probability of massive BH growth and
retention in a cluster. We find that, in most models, there is a significant
probability (~20-80%) of BH growth with final masses > 100 M_{\sun}. In one
case, a final BH formed with mass ~ 620 M_{\sun}. However, if the typical
merger recoil speed (due to asymmetric emission of gravitational radiation)
significantly exceeds the cluster escape speed, no growth ever occurs.
Independent of the recoil speed, we find that BH-BH mergers enhanced by
dynamical interactions in cluster cores present an important source of
gravitational waves for ground--based laser interferometers. Under optimistic
conditions, the total rate of detections by Advanced LIGO, could be as high as
a few tens of events per year from inspiraling BHs from clusters.
