Radiation Hydrodynamics and Thermodynamics

A new, simple and physically transparent derivation of thermodynamics and hydrodynamics of radiating fluids is presented. The hydrodynamics is then extended to strongly inhomogeneous radiating fluids. The presence of inhomogeneities gives rise, among other changes, to new stresses (the stresses that are added to the classical Eddington stresses). The physical basis of our analysis is the requirement that solutions to the governing equations agree with results of the experimental observations that constitute the empirical basis of equilibrium thermodynamics.