Coarse-grain model for internal energy excitation and dissociation of molecular nitrogen

► A rovibrational coarse-grain model is developed for nitrogen. ► In this model, energy levels of an ab initio database are lumped into bins. ► Rate coefficients are averaged assuming a uniform distribution within each bin. ► The coarse-grain model is used to study a 1D strong shockwave. ► Relaxation and dissociation processes are accurately described using a few equations.