Multifluid Modelling of Relativistic Radiation Hydrodynamics

TL;DR

This paper develops a multifluid variational framework for relativistic radiation hydrodynamics, revealing new thermodynamic constraints and connecting it to dissipative processes like bulk viscosity and heat conduction.

Contribution

It applies Carter's multifluid theory to derive fundamental equations of relativistic radiation hydrodynamics, establishing a universal approach with new thermodynamic constraints.

Findings

Derivation of radiation hydrodynamics within a multifluid framework

Identification of thermodynamic constraints for microscopic models

Demonstration of the model's relation to bulk viscosity and heat conduction

Abstract

The formulation of a universal theory for bulk viscosity and heat conduction represents a theoretical challenge for our understanding of relativistic fluid dynamics. Recently, it has been shown that the multifluid variational approach championed by Carter and collaborators has the potential to be a general and natural framework to derive (hyperbolic) hydrodynamic equations for relativistic dissipative systems. Furthermore, it also allows to keep direct contact with non-equilibrium thermodynamics, providing a clear microscopic interpretation of the elements of the theory. To provide an example of its universal applicability, in this paper we derive the fundamental equations of the radiation hydrodynamics directly in the context of Carter's multifluid theory. This operation unveils a novel set of thermodynamic constraints that must be respected by any microscopic model. Then, we prove that the radiation hydrodynamics becomes a multifluid model for bulk viscosity or heat conduction in some appropriate physical limits.