  I present a suite of three-dimensional simulations of the evolution of
initially-hot material ejected by starburst-driven galaxy outflows. The
simulations are conducted in a comoving frame that moves with the material,
tracking atomic/ionic cooling, Compton cooling, and dust cooling and
destruction. Compton cooling is most efficient of these processes, while the
main role of atomic/ionic cooling is to enhance density inhomogeneities. Dust,
on the other hand, has little effect on the outflow evolution, and is rapidly
destroyed in all the simulations except the case with the smallest mass flux. I
use the results to construct a simple steady-state model of the observed
UV/optical emission from each outflow. The velocity profiles in this case are
dominated by geometric effects, and the overall luminosities are extremely
strong functions of the properties of the host system, as observed in
ultra-luminous infrared galaxies (ULIRGs). Furthermore the luminosities and
maximum velocities in several models are consistent with emission-line
observations of ULIRGs, although the velocities are significantly greater than
observed in absorption-line studies. It may be that absorption line
observations of galaxy outflows probe entrained cold material at small radii,
while emission-line observations probe cold material condensing from the
initially hot medium at larger distances.
