THERMODYNAMICS OF A DIATOMIC GAS WITH ROTATIONAL AND VIBRATIONAL DEGREES OF FREEDOM

A thermodynamic theory for a diatomic gas with rotational and vibrational degrees of freedom is developed. The field equations are based upon the balance equations of mass density, momentum density, internal energy density, rotational energy density, and vibrational energy density. The generality of the constitutive equations is restricted by the principle of material frame indifference, and by the entropy principle. Besides, a statistical theory is developed to get more explicit results for the constitutive equations. The problem concerning the propagation of plane harmonic waves of small amplitudes is also analyzed.