  The pairwise kinematic Sunyaev-Zel'dovich (kSZ) signal from galaxy clusters
is a probe of their line-of-sight momenta, and thus a potentially valuable
source of cosmological information. In addition to the momenta, the amplitude
of the measured signal depends on the properties of the intra-cluster gas and
observational limitations such as errors in determining cluster centers and
redshifts. In this work we simulate the pairwise kSZ signal of clusters at z<1,
using the output from a cosmological N-body simulation and including the
properties of the intra-cluster gas via a model that can be varied in
post-processing. We find that modifications to the gas profile due to star
formation and feedback reduce the pairwise kSZ amplitude of clusters by ~50%,
relative to the naive 'gas traces mass' assumption. We demonstrate that
mis-centering can reduce the overall amplitude of the pairwise kSZ signal by up
to 10%, while redshift errors can lead to an almost complete suppression of the
signal at small separations. We confirm that a high-significance detection is
expected from the combination of data from current-generation, high-resolution
CMB experiments, such as the South Pole Telescope, and cluster samples from
optical photometric surveys, such as the Dark Energy Survey. Furthermore, we
forecast that future experiments such as Advanced ACTPol in conjunction with
data from the Dark Energy Spectroscopic Instrument will yield detection
significances of at least 20{\sigma}, and up to 57{\sigma} in an optimistic
scenario. Our simulated maps are publicly available at:
http://www.hep.anl.gov/cosmology/ksz.html
