The explicit closure for the ultrarelativistic limit of Extended Thermodynamics of Rarefied Polyatomic Gas

Abstract

In a recent paper the ultra-relativistic limit of a recent theory proposed by Pennisi
and Ruggeri for polyatomic relativistic gas has been considered. This was important
to check the general article. In particular, the explicitly expression of the characteristic
velocities of the hyperbolic system were found for every value of the parameter a
measuring ”how much” the gas is polyatomic. This result was achieved in terms of the
components of the main field as independent variables and without writing it in terms
of the physical variables. Here the closure of the field equations is considered in terms
of these physical variables and their ultrarelatistic limit is obtained.