  The large neutrino density in the deep interior of core-collapse supernovae
and compact binary merger remnants makes neutrino flavor evolution non-linear
because of the coherent forward scattering of neutrinos among themselves. Under
the assumption of spherical symmetry, we model neutrino decoupling from matter
in an idealized setup and present the first non-linear simulation of flavor
evolution in the presence of charged current and neutral current collisions, as
well as neutrino advection. Within our framework, we find that flavor
transformation occurs before neutrinos fully decouple from matter, dynamically
affecting the flavor distributions of all neutrino species and shifting the
location of the neutrino decoupling surfaces. Our results call for further work
as they may have implications on the explosion mechanism of supernovae, the
nucleosynthesis of the heavy elements, as well as the observable neutrino
signal, all of which is yet to be assessed.
