Two-dimensional axi-symmetric gas-solid two-fluid model was established. Under three conditions of source: E0/10,E0/100,E0/1 000 (initial energy per mass of gas),diminishing of gas energy and gas pressure caused by packing particles was studied. It shows that: With higher initial energy per mass of source kinetic and internal energy of gas is diminished by packing particles more quickly,gas fluid is close to stillness more quickly,gas pressure is decreased more quickly.

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.

For evaluating damage of strong explosion,boundary conditions of coupled Eulerian-Lagrangian calculation are used.Energy accumulation due to radiative transfer is considered.Coupled methods of two-dimensional numerical simulation with cylinder symmetry are established,which calculate simultaneously equations of radiation hydrodynamics and hydro-elasto-plastic.Full physical processes of underground strong explosion are presented.They are propagation of radiation front in detonating room,transmitting of radiative energy to wall of detonating room,inward expanding of detonating room wall,propagation of shock wave in rock,compressing of high-pressure in detonating to room wall and outward expanding like waves of detonating room wall.

One-dimensional radiation hydrodynamics equations with spherical symmetry are used to study early development of fireball front and case shocks in strong explosion.Numerical method for radiation transport equations is established.The calculation results agree well with Brode's.Early formation of fireball front and case shocks in strong explosion at different yield,density in explosion zone and altitude are simulated numerically.Calculation results are analyzed.

Equations in a non-relativistic average atom model for plasmas are solved.Numerical techniques,global chart and code design are given in detail.Semi-analytical results obtained by variational method and test-potential method are compared with those by full numerical method in the same model and those in different physical models.Advantages and limitations of the model and algorithm are pointed out.