  After the initiation of the explosion of core-collapse supernovae, neutrinos
emitted from the nascent neutron star drive a supersonic baryonic outflow. This
neutrino-driven wind interacts with the more slowly moving, earlier supernova
ejecta forming a wind termination shock (or reverse shock), which changes the
local wind conditions and their evolution. Important nucleosynthesis processes
(alpha-process, charged-particle reactions, r-process, and vp-process) occur or
might occur in this environment. The nucleosynthesis depends on the long-time
evolution of density, temperature, and expansion velocity. Here we present
two-dimensional hydrodynamical simulations with an approximate description of
neutrino-transport effects, which for the first time follow the post-bounce
accretion, onset of the explosion, wind formation, and the wind expansion
through the collision with the preceding supernova ejecta. Our results
demonstrate that the anisotropic ejecta distribution has a great impact on the
position of the reverse shock, the wind profile, and the long-time evolution.
This suggests that hydrodynamic instabilities after core bounce and the
consequential asymmetries may have important effects on the
nucleosynthesis-relevant conditions in the neutrino-heated baryonic mass flow
from proto-neutron stars.
