The implementation flow of processing incompressible Navier-Stokes equations based on velocity-correction schemes is introduced, and velocity-correction schemes based on Picard iteration is developed by introducing Picard linearization to process the convection term in the velocity governing equation. Compared with the traditional method, the projection method after Picard linearization can be solved with a larger time step, which improves the stability of the solution method, and the convergence accuracy meets the requirements, which confirms the reliability of the solution method.

Effect of biofilm structure on bioreaction as well as flow and mass transfer are investigated with lattice Boltzmann method (LBM) on meso-scale. Porous construction of biofilm is regenerated by Quartet Structure Generation Set (QSGS) method, and LB method is coupled with multi-block model to obtain detail information and save computational cost. It indicates that properly increasing porosity benefits mass transportation between main region and biofilm, and hence improve substrate consumption efficiency under condition of stable biofilm structure. At given porosity of biofilm, changing growth construction of biofilm can also promote mass transfer between inner and outer of biofilm, leading to higher substrate consumption efficiency.

Two phase detonations of aluminum dust are simulated in a multi-fluid model to study particle energy calculation methods. In previous studies heat capacities of solid particles are constants, while realistic heat capacities change with temperature. In this simulation, effects of realistic heat capacities are studied. Numerical results show that detonation parameters are influenced significantly. The results with realistic capacities are close to experiments, while the results with fixed capacities overestimate pressure and detonation velocity. In detonation initiation, run-up distance is mainly decide by ignition energy, while realistic effect makes the distance shorter than that in the fixed heat capacity case.

An algorithm for pressure equation in a computational code PCCSAP-3 D,which is dedicated to analyze transient process of PCCS(Passive Containment Cooling System),is introduced.GMRES is introduced to accelerate calculation speed.Pre-conditioning of GMRES is applied.Convergence rates of GMRES and ML-ADI are compared.It shows that pre-conditioned GMRES can be used to solve pressure equations more efficiently.Since pressure equation coefficient matrix is structural and sparse,pre-conditioned GMRES is more efficient than ML-ADI as pressure equation coefficient matrix is larger.

A numerical method for simulation of interfacial flows with phase change is presented. A volume-of-fluid (VOF) method based on piecewise linear interface construction (PLIC) is used to track interface. Spocial treatment is taken to deal with discontinuous velocity field due to phase change at liquid-vapor interface. The treatment is easy and effective. SIMPLE method is used for flow field and a CSF model for surface tension. The method is used to simulate three-dimensional film boiling on a horizontal plate with Cartesian coordinates and axisymmetric two-dimensional natural convection film boiling on a hemisphericallyended rod with body fitted coordinates. They are in good agreement with analytical correlations.

Monte Carlo simulation is performed to study the magnetic properties of mixed spin-1 and spin-3/2 ferrimagnetic systems in a one-dimensional spin chain with single-ion anisotropy.It is found that magnetization plateaus in external fields at ground state exist.A phase diagram of mixed spin-1 and spin-3/2 ferrimagnetic systems is obtained.The magnetic plateaus and the phase diagrams of the system are explained well with analysis of energy and spin configuration.

With analysis of conduction band structure and isotropic relaxation time approximation, an analytical model for the electron Hall mobility and Hall scattering factor of n-type 6H-SiC is proposed. The impact of different scattering mechanisms on the low field electron transport in 6H-SiC is illustrated clearly. Three ellipsoidal and parabolic constant energy surfaces simplification are used. The calculated results are in good agreement with physical measurements.

The electron transport properties in 2H-,4H-,and 6H-Silicon Carbide are investigated numerically with an ensemble Monte Carlo technique.The acoustic phonon deformation potential scattering,polar optical phonon scattering,intervalley phonon deformation scattering,ionized impurity scattering and neutral impurity scattering are considered.The electron mobilities of 2H-,4H-,and 6H-SiC as a function of temperature at low electric field are obtained.The influence of the neutral impurity scattering on the transport property of 4H-SiC is discussed in detail.Finally,the static and transient variation of electron drift velocity in high electric fields are studied.The peak transient velocity in an electricfield of 1.0×10⁶ V·cm^-1 is 3.3×10⁷cm·s~(-1) for 4H-Sic and 3.0×10⁷ cm·s^-1 for 6H-Sic when the electric field is applied perpendicular to the c axis.The simulated results are in good agreement with recent experiments in a wide range of temperature and electric field.