  Globular clusters are considerably more complex structures than previously
thought, harbouring at least two stellar generations which present clearly
distinct chemical abundances. Scenarios explaining the abundance patterns in
globular clusters mostly assume that originally the clusters had to be much
more massive than today, and that the second generation of stars originates
from the gas shed by stars of the first generation (FG). The lack of
metallicity spread in most globular clusters further requires that the
supernova-enriched gas ejected by the FG is completely lost within ~30 Myr, a
hypothesis never tested by means of three-dimensional hydrodynamic simulations.
In this paper, we use 3D hydrodynamic simulations including stellar feedback
from winds and supernovae, radiative cooling and self-gravity to study whether
a realistic distribution of OB associations in a massive proto-GC of initial
mass M_tot ~ 10^7 M_sun is sufficient to expel its entire gas content. Our
numerical experiment shows that the coherence of different associations plays a
fundamental role: as the bubbles interact, distort and merge, they carve narrow
tunnels which reach deeper and deeper towards the innermost cluster regions,
and through which the gas is able to escape. Our results indicate that after 3
Myr, the feedback from stellar winds is responsible for the removal of ~40% of
the pristine gas, and that after 14 Myr, ~ 99% of the initial gas mass has been
removed.
