Kinetic Theory of Irreversible Processes in a System of Radiation and Matter
Thermodynamics of irreversible processes in a radiation field is formulated, based on kinetic theory, by treating nonequilibrium radiation as a nonequilibrium photon gas interacting with matter. The generalized hydrodynamic equations for macroscopic variables necessary for describing temporal and spatial evolution of irreversible processes in the system of matter and radiation are derived from kinetic equations by using the modified moment method. The method rigorously yields the conclusion that entropy differential is not an exact differential when the system is away from equilibrium. Therefore, an extended Gibbs relation for the entropy density does not hold valid. However, an extended Gibbs relation-like equation holds for the compensation differential which has been shown to be an exact differential. The entropy balance equation is cast into an equivalent form in terms of a new function called the Boltzmann function. In the context of the present formalism the light-induced viscous flow is theoretically explained for the entire range of pressure. The modified moment method has been extended to the covariant Boltzmann equation in order to formulate a theory of relativistic irreversible thermodynamics. Furthermore, the kinetic theory foundations for relativistic irreversible thermodynamics for the system of radiation and matter are provided. The statistical mechanical formulas are obtained for various material and radiative transport coefficients. The radiative transport coefficients stand in simple ratios independent of material parameters. The ratios calculated are in agreement with those used in the phenomenological theory using the Rosseland mean.
- Pub Date:
- GIBBS RELATION;
- Physics: Radiation