Non-equilibrium relativistic two-phase flow with heat exchange
We consider two different systems of hyperbolic balance laws governing relativistic two-phase flows with general equations of state. The phases are assumed to be immiscible. In the first one the thermal equilibrium is attained through a relaxation procedure consistent with the second law of thermodynamics, while the second is a fully relaxed model in which the two phases reach an equal temperature instantaneously. Finally, we deduce and compare the wave velocities for both the models: the hydrodynamical velocity of the relaxed system can never exceed that of the relaxation system.