Magnetic dynamic properties of Fe nanorings with small defects were simulated with Monte Carlo method. It is found that hysteresis loops of small defect Fe nanoring have "bistable" characteristics, which is consistent with experimental results. Energy research shows that vortex states appear in the region of local energy minimum. Remanence of defect system changes with defect location: The remanence increases first and then decreases with the increase of Y, and remains relatively stable in the middle region. Spin configuration of the system explains the above phenomenon well.

In simulation of a charged particle's guiding-center orbit in Tokamak equilibrium configurations, an efficient way to build physical functions such as magnetic field was obtained. Discrete Fourier transform is applied to replace cubic spline interpolation and B spline interpolation methods in calculation of gulding-center's trajectory. It has same accuracy as cubic spline interpolation and facilitates calculations in tearing mode as well. The method holds naturally property of symmetry. Derivatives of 3rd order or above can be obtained easily. Moreover, effect of incorrect data is reduced to the minimal limit compared with cubic spline interpolation.

With Monte Carlo simulation,we study magnetic properties and controllable vortex circulation of asymmetric Co nanorings.Simulated results indicate that magnetic field direction has great effect on magnetic states and magnetization process of asymmetric Co nanorings.It is found that direction of the magnetic-moment circulation in asymmetric nanorings can be controlled by gradient of the domain-wall energy along the circumference in cooperation with an external magnetic field.It is found that size effect is obvious on stability of vortex-type state and magnetization process of asymmetric nanorings.

Orbital evolution of RKBOs is simulated by using reliable orbital elements over a timescale of 10⁸ year.It shows that their orbits are relatively stable in resonant regions.Stability depends on initial orbital semi-major axis,eccentricities and inclinations of these resonant bodies.According to dynamical behavior of orbital semi-major axis,eccentricity and inclination,RKBOs are classified into regular or chaotic orbits.

We apply effective dipole approximation to investigate the equivalent dielectric constant of inclusion and the effective response and optical absorption in composites media of metal spherical particles.The dielectric constant varies along the radius of the particles.ε_e exhibits a monotonic decrease with the power index n while the dielectric constant shows a power law gradation.The presence of the gradation in metal particles yields a resonant optical absorption peak.It shows red-shift with m_ω and m_ν of the metal-dielectric composites.

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.

The Runge-Kutta-Fehlberg algorithm(RKF),the symplectic algorithm and the Hermite algorithm for N-body problems are studied with energies errors and semimajor axis and eccentricity.It shows that the precision of RKF is the highest,but its error increases with computation time.The symplectic algorithm has no artificial dissipation,and keeps stability of the energy error.The structure of the Hermite algorithm is simple and its computation time is short,but its error is greater than that of the other two.

Numerical calculations on Josephson junctions under microwave radiation are made by means of Runge-Kutta method in the RSJ model. The DC I-V curves of Josephson junctions reproduce experimental results very well.

Four turbulence models:algebraic Baldwin-Lomax model with Degani-Schiff modification, two versions of Johnson-King model (J-K90A and J-K92) and two-equation k-g model, are described and evaluated for missile supersonic flow, NASA TN D-712 standard model and the civil airplane wing-body configuration (two-block C-O mesh) transonic flows. The 3-D compressible Reynolds averaged Navier-Stokes (RANS) equations are integrated numerically by central-difference with artificial viscosity scheme, finite volume formulation and explicit multi-step Runge-Kutta algorithm. The turbulence equations of k-g model are explicitly solved in the same way as the RANS. Results show that all models can perform well for attached and mildly separated flows. For large angle-of-attack separated flow over the missile, k-g and J-K92 models match the experimental results much better than those with B-L and J-K90A models. According to the B-L model with some modification, the shock location logs behind those with the other three models for the civil airplane geometry. Model k-g, because of its advantages such as without using normal-to-wall distance, simple source terms and straightforward boundary conditions, performs best in the four models for complex configuration with multi-block mesh system or multi-wall interference. B-L and J-K models, despite of cheapness and robustness, both base on empirical Prandtl mixing-length hypothesis and need to calculate the distance normal to the wall, undoubtedly limiting the application scope of these models for multi-block mesh system and complex geometry.

A method for the adaptive refinement of a Quad/Cartesian grid for the solutions of the Euler and N-S equations is presented.An adaptive Quad/Cartesian hybrid grid method,which retains the advantages of the Cartesian grid approach and, at the same time, touches the viscous flow problems,is provided.The body fitted Quad grids are generated around the body and the Cartesian grids are used in the remains of the flow field.The flow solver of the Euler and N-S equations is performed by a conventional algorithm,including the finite volume method and the Runge-Kutta time-stepping scheme.The grid adaptation and the flow solver achieve reasonable efficiency and accuracy with minimum computer resources.Based on the above approach,the numerical analysis of flows around the single-element and the multi element airfoils is given.The numerical results presented show the flexibility of this approach and the accuracy attainable by the solution-based refinement.

Grid generation and flow analysis methods for multi-element airfoil based on multi-block point-to-point patched grid technology are developed. Some strategies are developed to improve the efficiency, accuracy and applicability of the method.Several flow cases about multi-element airfoils are computed with the present method in order to validate it. Numerical results are in agreement with experiment data. Flow field visualization shows that the present method has good resolution in flow details.

A new unstructured Cartesian cutted grid generation method is introduced. The grid generation of some airfoils and wing is performed with the tree data structure. Euler equations are solved using the cell-centred finite volume method. The results of flow field computation are in agreement with the experiments. These facts show that the grid generation and the numerical calculation approach is correct and reasonable. Based on the above work, a flow field numerical simulation of wing and store separation is finished. This process provides a new way and tool for the more accurate solver of the unsteady flow problem.

Because of the complexities in both configurations and flow phenomena,there are great difficulties in the numerical simulation of flow about wing with lift-enhancing devices and control surfaces.By using cell-centered finite volume method,it deals with Renolds-averaged Navier-Stokes equations on multi-block structural grids generated by elliptic method.Two kinds of patching schemes,point-to-point and patch-on-common-surface,are employed to establish the information exchange among blocks.In the later one,the overlap cell area weighted interpolation is used to guarantee the conservation.Ramshaw algorithm is also used to pre-determine the overlap areas.Flow fields about multi-element airfoils and delta wing with deflected flap are computed with the present method.Numerical results are all in good agreement with experiment data.Flow field visualization shows the present method has good resolution in flow details.

A Fast grid generation procedure named parabolic equation method for complex aircraft is developed. Grid is obtained by marching from body surface to outer boundary. Successful control of grid orthogonality on body is achieved by means of the introduction of algebraic grid prediction. A numerical algorithm based on a finite volume explicit scheme is employed for calculating transonic flow around a realistic aircraft configuration. Comparisons of the computational results with experimental data show very good agreement in terms of trends.

A body-fitted orthogonal grid around complex configurations including wing,body,pylon and nacelle has been suc-cessfully generated by applying the multi-block grid technique and the method of solving elliptic and parabolic partial differential e-quations.The transonic flow field and aerodynamic characteristics of the advanced twin engine transport aircraft are also simulated numerically by using finite volume methods to solve the Euler equations with high efficiency,and the viscous effect of wing bound-ary layer is considered.Results of the calculation show that pylon and nacelle have significant effect on the supercritical wing aerody-namic characteristics.the numerical results are in good agreement with the experimental wing surface pressure distribution data.

A simulation method has been developed for the analysis of powered engines,whose components include the outer cowl,spinner,fan face,fan exit plane,and core cowl geometry.In the simulation,either the mass flux or the static pressure can be prescribed at the fan face.The total pressure,total temperature,flow direction and the bypass ratio are specified at the turbine or fan exit plane,and the exhaust plume emerges naturally as part of the global solution.Comparison of numerical results with test data shows a very good agreement.

This paper deals mainly with applications of the finite-element method in numerical simulation of neutron well-logging.In the frame of multigroup P₁ approximation the neutron transport equation is soluted by using finite-element method and the two-dimentional finite-element code FEMLOG is developed for the numerical simulation of neutron well-logging.The precision of numerical results of FEM-LOG is satisfactorily comparable to that of the international common code DOT4.2.However FEM-LOG is operated on the computer far faster than DOT4.2.

This paper utilizes a series of analytical transformations to generate two-dimensional curvefitted, orthogonal meshes. The generated meshes can be regulated and controlled according to the variation of the flow parameters in the flow field so as to obtain the optimal grid distribution. As an example, taking unsteady transonic flows over oscillating NACA 0012 airfoil, the effects of transformation accuracy on computation accuracy of flow field, and how to control the grid generation corresponding with the variation of the flow parameters are analyzed in detail.The proceeding techniques have been applied to solve Euler equations with succes and the numerical results are satisfactory.