Fluid Mechanics of Strings
  We consider conserved currents in an interacting network of one-dimensional
objects (or strings). Singular currents localized on a single string are
considered in general, and a formal procedure for coarse-graining over many
strings is developed. This procedure is applied to strings described by the
Nambu-Goto action such as cosmic strings. In addition to conserved currents
corresponding to the energy-momentum tensor, we consider an antisymmetric
tensor of conserved currents related to the string tangent vector. Under the
assumption of local equilibrium we derive a complete set of hydrodynamic
equations for strings.
