Globally Hyperbolic Regularization of Grad's Moment System in One   Dimensional Space
  In this paper, we present a regularization to 1D Grad's moment system to achieve global hyperbolicity. The regularization is based on the observation that the characteristic polynomial of the Jacobian of the flux in Grad's moment system is independent of the intermediate moments. The method is not relied on the form of the collision at all, thus this regularization is applicable to the system without collision terms. Moreover, the proposed approach is proved to be the unique one if only the last moment equation is allowed to be alternated to match the condition of non-equilibrium independent characteristic speeds. The hyperbolic structure of the regularized system, including the signal speeds, Riemann invariants and the properties of the characteristic waves including the rarefaction wave, contact discontinuity and shock are provided in the perfect formations. 
Zhenning Cai, Yuwei Fan, Ruo Li
math-ph math.MP