  Approximating neutrino oscillations as subgrid physics is an appealing
prospect for simulators of core-collapse supernovae and neutron-star mergers.
Because flavor instabilities quickly lead to quasisteady states in oscillation
calculations, it is widely believed that flavor mixing can be approximated in
astrophysical simulations by mapping unstable states onto the appropriate
asymptotic ones. Subgrid models of this kind, however, are not self-consistent.
The miscidynamic theory of quantum-coherent gases furnishes a subgrid model
that is.
