  The flavor evolution of neutrinos in dense astrophysical sources, such as
core-collapse supernovae or compact binary mergers, is non-linear due to the
coherent forward scattering of neutrinos among themselves. Recent work in this
context has been addressed to figure out whether flavor equipartition could be
a generic flavor outcome of fast flavor conversion. We investigate the flavor
conversion physics injecting random perturbations in the neutrino field in two
simulation setups: 1. a spherically symmetric simulation shell without periodic
boundaries, with angular distributions evolving dynamically thanks to
non-forward scatterings of neutrinos with the background medium, and neutrino
advection; 2. a periodic simulation shell, with angular distributions of
neutrinos defined a priori and neutrino advection. We find that, independent of
the exact initial flavor configuration and type of perturbations, flavor
equipartition is generally achieved in the system with periodic boundaries; in
this case, perturbations aid the diffusion of flavor structures to smaller and
smaller scales. However, flavor equipartition is not a general outcome in the
simulation shell without periodic boundaries, where the inhomogeneities induced
perturbing the neutrino field affect the flavor evolution, but do not
facilitate the diffusion of flavor waves. This work highlights the importance
of the choice of the simulation boundary conditions in the exploration of fast
flavor conversion physics.
