Bulk viscosity in relativistic fluids: from thermodynamics to hydrodynamics

Abstract The approach of extended irreversible thermodynamics consists promoting the dissipative fluxes to non-equilibrium thermodynamic variables. In a relativistic context, this naturally leads formulation theory Israel and Stewart (1979), which is, date, one most successful theories for dissipation. Although generality principle makes it applicable any fluid, connection Israel–Stewart with microphysics has been established, through kinetic theory, only case ideal quantum gases. By performing convenient change variables, we provide, bulk viscosity, an equivalent reformulation equations at basis thermodynamics. This maps process contributes viscosity into set chemical reactions, whose reaction coordinates are abstract parameters describing displacement from local equilibrium fluid element. We apply our new formalism fluids, showing that model is just second-order expansion minimal belonging larger class non-perturbative include nuclear-reaction-mediated neutron star matter as particular case. Furthermore, show concrete examples provides ways computing directly defines simple prescription constructing generic bulk-viscous fluid.