  We consider the nucleation process associated with capillary condensation of
a vapor in a hydrophobic cylindrical pore (capillary evaporation). The
liquid-vapor transition is described within the framework of a simple lattice
model. The phase properties are characterized both at the mean-field level and
using Monte-Carlo simulations. The nucleation process for the liquid to vapor
transition is then specifically considered. Using umbrella sampling techniques,
we show that nucleation occurs through the condensation of an asymmetric vapor
bubble at the pore surface. Even for highly confined systems, good agreement is
found with macroscopic considerations based on classical nucleation theory. The
results are discussed in the context of recent experimental work on the
extrusion of water in hydrophobic pores.
