  Mature neutron stars are cold enough to contain a number of superfluid and
superconducting components. These systems are distinguished by the presence of
additional dynamical degrees of freedom associated with superfluidity. In order
to consider models with mixtures of condensates we need to develop a multifluid
description that accounts for the presence of rotational neutron vortices and
magnetic proton fluxtubes. We also need to model the forces that impede the
motion of vortices and fluxtubes, and understand how these forces act on the
condensates. This paper concerns the development of such a model for the outer
core of a neutron star, where superfluid neutrons co-exist with a type II
proton superconductor and an electron gas. We discuss the hydrodynamics of this
system, focusing on the role of the entrainment effect, the magnetic field, the
vortex/fluxtube tension and the dissipative mutual friction forces. Out final
results can be directly applied to a number of interesting astrophysical
scenarios, e.g. associated with neutron star oscillations or the evolution of
the large scale magnetic field.
