Considering the fact that large deviatoric deformations are always localized in a small narrow region in hypervelocity impact problems,a method named subdomain computation for SPH(smoothed particle hydrodynamics) is developed.The entire computational domain is divided into several subdomains.In subdomains where large deformation is developed more particles are placed,and in subdomains where only small deformation is developed fewer particles are placed.Computational instability induced at interface of two subdomains is discussed and a method to handle the instability is proposed.Numerical simulations of a rod projectile penetrating into a thick target are carried out with the method and traditional SPH.It shows that computation accuracy as well as computation efficiency are improved.

A multi-dimensional particle-in-cell code KLAP is introduced. Field ionization, impact ionization and two body collision are considered in a one-dimensional code. Moving window technology is used in a three-dimensional code to study laser wakefield acceleration in GeV region. Terahertz radiation, laser propagation in neutral gas medium, surface electron acceleration as well as GeV electron generation in laser wakefield acceleration are studied.

A mathematical model for multiple scattering of light conducted in polymers is presented.Based on the Mie scattering theory,Monte Carlo method is employed and a program is developed.By simulating scattering of a photon,we simulate problem with light source as laser or CCFL.Distribution of light out of source in polymers is obtained by statistic calculation.The results show that a plane light in polymer can be obtained with body scattering principle and intensity distribution of light escaping from polymer can be well controlled.

In numerical simulation of the air flow around Daya Bay nuclear power station (NPS),a simplified data assimilation method is used to restrain forecasting errors that are caused by the uneven distribution of observation data in time and space.The effect of data assimilation on the initialization field model is analyzed.It shows that the method restrains errors in initialization field and in model significantly.

A similarity model describing the physics of slab target X-ray lasers is constituted from the ideal hydrodynamic equations. The parameters of the plasma(e.g., temperature, density, and scale length) are predicted, which are important for the experimental design of slab target X-ray lasers. The model provides a mathematic tool for quantitatively predicting and explaining experimental results.