Modeling r-Process Nucleosynthesis in Hot Astrophysical Flows

While the basic mechanism of rapid neutron capture, or $r$-process, nucleosynthesis has long been understood, a definitive determination of the astrophysical site of the $r$ process remains elusive. Here we discuss various aspects of two potential sites---the core-collapse supernova neutrino-driven wind and hot outflows from black hole-neutron star mergers. We will pay particular attention to the role of neutrino interactions in these environments and to the importance of a careful understanding of nuclear properties far from stability for realistic $r$-process simulations.