Closure of the balance laws for gaseous mixtures near chemical equilibrium

The relaxation process towards mechanical and chemical equilibrium of a reacting gas mixture is modeled starting from the generalized Boltzmann equation which is linearized following a BGK-type approach. A first-order perturbation scheme of Chapman-Enskog type is performed in a flow regime close to chemical equilibrium and the reactive Navier-Stokes equations of the model are presented in the hydrodynamic form. Moreover, the transport coefficients of diffusion, shear viscosity and thermal conductivity are characterized in an explicit form which shows the dependence on elastic and chemical contributions