Abstract: An operator splitting method is developed for numerical simulation of strong explosion fireball.In the approach the system is split into two parts.One part couples radiation and fluid in a hyperbolic subsystem.Another parabolic part evolves radiation diffusion and source-sink terms.We propose a numerical method for stiff source term.It shows that the method maintains efficiency and satisfies the needs of engineering.At last,spatial distributions of parameters in nuclear explosion reflecting fireball evolution are given.The calculation agrees well with empirical formulas.

Key words: fireball, radiation hydrodynamics, stiff source term, operator splitting method