A Lagrangian formulation of relativistic Israel-Stewart hydrodynamics
  We rederive relativistic hydrodynamics as a Lagrangian effective theory using the doubled coordinates technique, allowing us to include dissipative terms. We include Navier-Stokes shear and bulk terms, as well as Israel-Stewart relaxation time terms, within this formalism. We show how the inclusion of shear viscosity, and the requirement of a bounded energy-momentum "vacuum", forces the inclusion of the Israel-Stewart term into the theory, thereby providing a justification for the origin and uniqueness of these terms. 
Giorgio Torrieri, David Montenegro
hep-th hep-ph nucl-th physics.flu-dyn