Third-Order Relativistic Fluid Dynamics Coefficients Calculated Using Extended Thermodynamics
Researchers developed third-order hydrodynamic equations using relativistic extended thermodynamics with 14 independent fields, calculating thermodynamic coefficients for ultra-relativistic and non-degenerate relativistic gas regimes. The work applies fundamental principles including relativity, entropy, and hyperbolic propagation of disturbances to derive fluid equations. These coefficients are important for modeling extreme astrophysical environments and provide benchmarks against kinetic theory predictions.
A new theoretical study presents third-order hydrodynamic equations derived from relativistic extended thermodynamics, expanding expressions for entropy, four-current, shear-stress tensor, dynamic pressure, and heat flux to cubic order. The framework is built on three foundational requirements: the relativity principle, the entropy principle, and hyperbolic propagation of disturbances. The authors explicitly calculate thermodynamic coefficients for two regimes: ultra-relativistic gases and non-degenerate relativistic gases. The non-degenerate regime simplifies the coefficients by eliminating fugacity, enabling straightforward normalization, while the ultra-relativistic regime establishes upper bounds. Comparisons with earlier kinetic theory calculations show good agreement on some coefficients, though others differ slightly, suggesting refinements to existing models.
What's missing
The study does not discuss potential applications to specific astrophysical systems (e.g., neutron stars, quark-gluon plasma) or experimental validation methods. The limitations of the third-order approximation and conditions under which higher-order terms become significant are not detailed in the abstract.
What different sources said
- arXiv astro-phCenter
Thermodynamic coefficients in third-order relativistic fluid dynamics
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