A three-dimensional (3D) free-parameter multiple-relaxation-time lattice Boltzmann method for high speed compressible and low speed incompressible flows is presented. In the approach transformation matrix is constructed according to irreducible representation basis functions of SO(3) group. Equilibria of nonconserved moments are chosen so as to recover compressible Navier-Stokes equations through Chapman-Enskog analysis. Sizes of discrete velocities are flexible. Influence of model parameters on numerical stability is analyzed. Reference values of parameters are suggested. To validate performance of the model, several well-known benchmark problems ranging from 1D to 3D are simulated. Numerical results are in good agreement with analytical solutions and/or other numerical results.

A discrete Boltzmann model is presented for detonation simulation. It consists of a discrete Boltzmann equation and a phenomenological reaction rate equation. In physical modeling, it is equivalent to a traditional Navier-Stokes model and a coarse grained model for thermodynamic non-equilibrium behavior. Compared with traditional fluid model, it provides more dynamic information and more kinetic information as well. The model adopts 16 discrete velocities, which has high computational efficiency. Additional degrees of freedom are introduced so that it can be used to simulate various detonations with different specific heat ratios. Several classic examples of detonation are simulated to validate the model. It shows that besides detonation dynamics where traditional hydrodynamic model works, it can also be used to study non-equilibrium effects where traditional fluid model does not work.

Dynamics of a pair of voids located along loading direction under uniaxial tension is investigated using molecular dynamics method.Size effects in void growth and coalescence are studied.It shows that different-sized voids grow and coalesce through dislocation nucleating on void surfaces.In early elastic stage,voids grow along loading direction,then along vertical direction and finally form octahedral-like structures in plastic stage.Critical yield stress increases with decreasing of void size.If radius is large,dislocations nucleate and migrate symmetrically.Voids elongate in loading direction,and evolution process is similar.If radius is small,dislocations nucleate asymmetrically and voids elongate along vertical direction.The process of void growth may be characterized by elastic deformation,independent growth,coalescence and steady growth.Independent growth stage diminishes gradually as void size becomes smaller.

Based on thermodynamics and energy conservation law, an elastic body physical model is established. A physical equation of infrared radiation temperature and radiant exitance is achieved. With finite element method(FEM) the model can be used to analyzing infrared radiant energy of a three-point bending beam of elastic-photo material subjected to external loading in room-temperature. It shows that results calculated are highly coincidence with those of experiments. The model and relative theories are rational in quantitative analysis. A quantitative method is shown to analyse and reveal mechanism of infrared radiation of solid materials by computer.

A method constructing atom distribution of dislocation configurations based on dislocation theory of continuous medium is presented. Theoretically, this method can be used to construct dislocations with any shape and any Burgers vector. For verification purpose, we construct a linear edge perfect dislocation with Burgers vector b=[110]/2 and a partial dislocation ring with b=[112]/6 in FCC copper. Decomposition process of a edge perfect dislocation and contraction of a partial dislocation ring driven by self-force is simulated. Simulation results agree well with theoretical analysis. The method shows significant superiority in constructing glissile dislocation loops which are generally difficult in other schemes.

A further study to a one-dimensional CI transition model is given.The period of the external potential D has a critical value Dc.The phase diagram in the case of D < c is greatly different from that in the case of D > c.When D < c,the phase diagram varies with D and exhibits Farey tree structure in most region of D.When D > c,the phase diagram keeps in the same shape and do not satisfy the Farey tree structure.The procedure of phase transition is studied through the effective potential F(u).

The best coupling structure of the reflective-type-semicircular-optical fiber probe has been studied by using the method of numerical simulation. Distributive curve of the intensity of the reflective light on the incident plane of the light is given by computer simulation to the different radii of optical fiber cores which are separately 3μm, 5μm, 10μm, 15μm. and the radius of the optical fibers are totally 20m. The results show that the best coupling radius of the reflective type semicircular optical fiber probe satisfies the formula. ρ_max=R-0.01004a³+0.37429a²-3.38095a+16.85714(μm).