A Causal Formulation of Dissipative Relativistic Fluid Dynamics with or without Diffusion

The article proposes a causal five-field formulation of dissipative relativistic fluid dynamics as a quasilinear symmetric hyperbolic system of second order. The system is determined by four dissipation coefficients eta, zeta, kappa, mu, free functions of the fields, which quantify shear viscosity, bulk viscosity, heat conductivity, and diffusion.