Dialog Concerning the Two Shock Codes

Abstract In this paper, we summarize the shock physics and the treatment of radiative transfer in two well-established shock codes—the MAPPINGS code and the Cox/Raymond code. We compare the ionization states, temperatures, electron densities, and energy transportations of the shock models with shock velocities of 50, 110, 150, and 300 km s −1 . In summary, both codes adopt the Rankine–Hugoniot flow equation to describe the shock flows, giving the same shock physical properties in the immediate area behind the shock fronts. The different treatments of radiative transfer in these two codes lead to somewhat different computations of the ionization and thermal structures of shocks, as well as the emission-line fluxes. This work highlights the importance of the delicate treatment of photoionization in shock models, providing insight for the future development of shock codes, such as 3D shock codes.