The present report describes numerical thermofluid simulation results of various gas arcs in a nozzle space at atmospheric pressure on the assumption of local thermodynamic equilibrium condition. It is crucial to investigate fundamentals on arc extinction phenomena by numerical simulation approach as well as experimental approach. The SF6, Ar, CO2 and N-2 arcs in our experimental setup were treated for the present calculation because we can accurately control the voltage and arc current in our experimtants and we can perform accurate electron density measurements for fundamental investigation and comparison. Two-dimensional temperature distributions in various gas-blast arcs were calculated in a steady state at a direct current of 50 A. Furthermore, transient temperature distributions in these arcs were computed under free recovery condition. Then, we calculated transient responses under free recovery condition by using calculated results in the steady state. The calculated arc voltage in the steady state and the transition of electron density under free recovery condition were compared with those obtained by laser Thomson scattering method in our experiments.