Central schemes for balance laws of relaxation type

Several models in mathematical physics are described by quasi-linear hyperbolic systems with source term and in several cases the production term can become sti. Here suitable central numerical schemes for such problems are developed and applications to the Broadwell model and extended thermodynamics are presented. The numerical methods are a generalization of the Nessyahu-Tadmor scheme to the nonhomogeneous case by including the cell averages of the production terms in the discrete balance equations. A second order scheme uniformly accurate in the relaxation parameter is derived and its properties analyzed. Numerical tests con rm the accuracy and robustness of the scheme.