  We analyze the V-band photometry data of the Be star omega CMa, observed
during the last four decades. The data is fitted by hydrodynamic models based
on the viscous decretion disk (VDD) theory, in which a disk around a
fast-spinning Be star is formed by material ejected by the central star and
driven to progressively wider orbits by means of viscous torques. For the first
time, we apply the model for both the disk build up and the dissipation phases.
Our simulations offer a good description of the photometric variability in both
phases, which suggests that the VDD model adequately describes the disk
structural evolution. Furthermore, our analysis allowed us to determine the
viscosity parameter (alpha) of the gas, as well as the net mass loss rate. We
find that alpha is variable, ranging from 0.1 to 1.0, and that build up phases
have larger values of alpha than the dissipation phases. Additionally, we find
that, contrary to what is generally assumed, even during quiescence the outward
mass flux is never zero, suggesting that the star alternates between a high
mass-loss phase (outburst) and a low mass-loss phase (quiescence).
