Many exploding astrophysical objects are multimessenger events that involve the emission of gravitational waves, electromagnetic signals, element synthesis, and the release of enormous numbers of neutrinos. To understand these signals, we need a careful accounting of the microphysics that occurs during and after the merger. One rapidly evolving area is the application of neutrino flavor transformation physics to large-scale simulations. I will review new developments in this area and discuss the importance of these developments to predictions of heavy element synthesis and the astrophysical origin of the r-process.