Archive

25 January 2004, Volume 21 Issue 1 Previous Issue    Next Issue

---

For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Select

The Domain Decomposition Parallel Iterative Algorithm for the 3-D Transport Issue YANG Shu-lin, MO Ze-yao, SHEN Long-jun 2004, 21(1): 1-9.  Abstract ( )   PDF (272KB) ( )   Discussion is given on the domain decomposition parallel iterative algorithm,which is aimed at the implicit difference equation under 3-D Cartesian coordination and the error estimates for both the serial and the parallel iteration are provided.The analysis and comparison about the numerical results indicate that the parallel iterative algorithm is highly parallelizable and scalable.

Select

Shaping by Using Quasi Gradient Decent Algorithm at Variable Sampling Intervals ZHAO Yi-qiong, WU Yuan, ZHOU Qiu-gui, LI Yong-ping 2004, 21(1): 10-14.  Abstract ( )   PDF (226KB) ( )   Numerical Hankel transform for circularly symmetric system at variable sampling intervals in input and optput planes is presented. An improved hybrid algorithm by using quasi Gradient Decent algorithm and spectrum selectivity is applied to the design of pure phase elements (PPE) in uniform illumination. Considering heat conductivity the simulated result shows that 97.2% of the incident beam energy is homogeneously concentrated into the desired focal spot in the target plane, and it fits to the required profile with the top profile error 1.1%.

Select

Numerical Verification of the Advantages of the Generalized Characteristic Coordinate System in Computing Expansive Wave and Shock Waves CHEN Zheng, SHI Jing, WU Zi-niu 2004, 21(1): 15-20.  Abstract ( )   PDF (217KB) ( )   In the generalized characteristic coordinate system(GCCS) proposed by the authors elsewhere, the frame moves at a speed which is a linear combination of the convective speed and the sound speed.This coordinate system is applied to the computation of the one-dimensional Euler equation and the advantages of GCCS is demonstrated in capturing expansive waves and shock waves.

Select

Boundary Conditions in Lattice Boltzmann Method NIE De-ming, LIN Jian-zhong 2004, 21(1): 21-26.  Abstract ( )   PDF (250KB) ( )   Comparison and discussion of several boundary conditions in lattice Boltzmann method are presented. To achieve improved accuracy, a new method based on the idea of standard bounce-back scheme is proposed. Numerical simulations for two-dimensional Poiseuille flow and unsteady Couette flow are carried out using d2q9 model, and the results are identical to the analytical solutions. The convergence for different boundary treatments is discussed by changing single relaxation time τ and Re number. The results show that LBM can recover Navier-Stokes equation at low Mach number. It is also indicated that the errors for large τ are much bigger than those for τ close to 1.

Select

Generation of 2-D Adaptive Structured Grids by Variational Methods YU Ming 2004, 21(1): 27-34.  Abstract ( )   PDF (484KB) ( )   An adaptive generation method about two dimensional structured grids is presented.Several variational methods are used to control the mesh spacing,smoothness,orthogonality and regularity of grids generated.The all governing equations have identical dimensions.Some typical examples demonstrate that the method of adaptively generating grids can well converge to the unique solution of the governing partial differ-ential equations, and in the meanwhile can get structured grids.

Select

Controlling Chaos by Straight-line Stabilization Method in Two Coupled Standard Maps XU Quan, CHEN Shao-ying, XU Hai-bo 2004, 21(1): 35-42.  Abstract ( )   PDF (241KB) ( )   The stabilization of an unstable periodic orbit in a neighborhood of an unstable fixed point is studied. By adding the external control signal, the straight-line stabilization method is applied to a high-dimensional Hamiltonian system, that is,two coupled standard maps. The method can stabilize an unstable periodic orbit in a neighborhood of an unstable fixed point, so the difficult problem of the unstable periodic orbits for high-dimensional Hamiltonian systems can be solved. The method does not require any previous knowledge of the system and is robust under the presence of weak external noise.

Select

Preliminary Analysis of Heat Transfer in Micro Water Resistojet LÜ Xiao-chen, JIANG Pei-xue, REN Ze-pei, SUN Xi-jiu 2004, 21(1): 43-48.  Abstract ( )   PDF (306KB) ( )   The characteristics of boiling and the superheat limit temperature in the micro water resistojet are analyzed. The beginning moment of heat transfer in micro-thrusters is described by the classical model of Fourier's law, the non-Fourier "Cattaneo-Vernotte"(C-V) model and the non-Fourier "dual phase lag"(DPL) model of heat conduction, respectively. The governing equations are numerically solved by using the finite difference method. The results show that there is a time delay between Fourier model and non-Fourier models. The heating resistor and a little amount of adjacent water reach the temperature of 300℃ quickly. However, most of the water is still in a comparatively low temperature.

Select

Monte Carlo Simulation of Spin Reorientation in Magnetic Thin Film XIAO Yan, FENG Qian, CHEN Zhi-gao, LI Yong-sen, ZENG Min-yong, HUANG Zhi-gao 2004, 21(1): 49-53.  Abstract ( )   PDF (245KB) ( )   The spin reorientation of magnetic thin film on a simple cubic lattice is simulated by employing Monte Carlo method.The influence of the magnetic anisotropy and the long-range dipolar interaction on the spin configurations of the system is also studied in detail.Meanwhile,the phase diagrams and the distributions of spin configuration,magnetization,specific heat of the systems are obtained.The results show that in a range of parameters,a transition from out-of-plane to in-plane ordering with the increase of the temperature is possible.

Select

Reconstruction of the Shape of Unknown Obstacles in Freshwater ZHUANG Hong-wei, MA Yi-chen, ZHANG Zhi-bin, WANG Jian 2004, 21(1): 54-60.  Abstract ( )   PDF (210KB) ( )   The inverse scattering problem is converted to an operator equation F(Γ)=f, which consists of the far field operator F, the measured far field data f and the shape Γ of the unknown obstacle. Using the Levenberg-Marquardt method and the derivative of F on Γ, in-troduced by A. Kirsh, this equation is solved and the shape Γ is determined. The numerical results show that this algorithm is practical and efficient.

Select

Stability and Transition of Hypersonic Boundary Layer Flow LIU Jia, LEI Mai-fang, YAO Wen-xiu, WANG Fa-min 2004, 21(1): 61-67.  Abstract ( )   PDF (278KB) ( )   The stability analysis and transition prediction are proceeded for one-order compression ramp,which is the valuable configuration for the hypersonic vehicles.The finite volume method is used to solve the NS equations to get the basic flow field.The solution of the eigenvalue problem is obtained by using the linear stability theory under the assumption of local parallel flows.The first mode and the second mode unstable waves are found at the Mach number of 6.With the relation of the temporal and spatial amplification rates,the transition position is predicted by the EN method.

Select

Deep Insight into Meshless Method and Application of Base-enriched EFG in EM Field Computation YIN Hua-jie, WU Jian-hua 2004, 21(1): 68-76.  Abstract ( )   PDF (429KB) ( )   Algorithm and programming by using base-enriched EFG method to solve 2D electromagnetic problems are addressed.Differential from other literatures, the EFG discrete form is obtained strictly from the integration of the weighted residual of the partial differential equation over the support domain of each node in a very straightforward way here. A deep insight into the kernel technique of EFG,the moving least square(MLS) method, is also presented from a data fit viewpoint. Computation is made for examples by using both the EFG and the FEM methods for comparison and demonstration purposes.

Select

Nanocontact Continuum Model and Calculation of Micro-mechanic TIAN Wen-chao, JIA Jian-yuan 2004, 21(1): 77-80.  Abstract ( )   PDF (139KB) ( )   Based on three Hamaker hypothesizes and Lennard-Jones potential, the model of rigid sphere-panel nano-contact is presented to solve the micromechanic "microcollision" and "nanocontact" problems, and the adhesion equations between the sphere and the first layer atom or the N layer atom of the panel are obtained by continuum method. The conclusion shows that the principal atoms affecting nanocotact force are the minority layers closing the contact zone.

Select

Numerical Simulation of the Distribution of Temperature and Velocity in a Free-burning Arc XU Xiang, GONG Ye, LIU Jin-yuan, ZHENG Shun 2004, 21(1): 81-85.  Abstract ( )   PDF (186KB) ( )   The SIMPLE algorithm is used to solve the MHD equations and the solutions of MHD equations are presented for the whole free-burning arc, excluding the electrodes. The SIMPLE algorithm has been revised in order to solve MHD equations and the flow chart is showed. A self-consistent numerical solution of the MHD equations yields the temperature and velocity distributions. And different types of radiation term are examined on the numerical results and it is found that the radiation term redults in a small decrease on the temperature of the arc.

Select

Characteristic Analysis of Electromagnetic Fields Generated by Electrostatic Discharge Spark BI Zeng-jun, SHENG Song-lin, FAN Li-si, LIU Shang-he 2004, 21(1): 86-90.  Abstract ( )   PDF (193KB) ( )   Electromagnetic pulse(EMP) generated by electrostatic discharges(ESD) can severely interfere with the normal operation of electronic systems and even damage them.In this paper,a modified dipole model of ESD spark is presented and the characteristic of electromagnetic fields generated by ESD spark is analyzed qualitatively using the model.Some conclusions are drawn and helpful to further study ESD electromagnetic protection measures.

Select

The Simulating and Characters of P-wave Seismic Record in the Fracture Medium GUI Zhi-xian, HE Zhen-hua 2004, 21(1): 91-94.  Abstract ( )   PDF (333KB) ( )   Determining the stratum fracture as an essential approach to the field of prospecting oilgas and engineering detecting based on P-wave is very difficult. Seismic wave field is complicated in the isotropy medium where there are some fracture because of the scattering.To recognize seismic wave character in the fracture stratum, this paper deals with the simulating seismic record of the fracture medium and uniformity stratum based on sound wave equation and by using high order finite difference method for improving precision. Meanwhile, it analyzes the change of the characters of seismic wave field in the strap of fracture growth. Results indicate that it is feasible to detect the fracture by dynamics characters of P-wave.