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25 December 1996, Volume 13 Issue 4 Previous Issue    Next Issue

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SMOOTHED PARTICLE HYDRODYNAMICS (SPH) METHOD (A REVIEW) Zhang Suochun 1996, 13(4): 385-397.  Abstract ( )   PDF (435KB) ( )   This paper describes a new and pure Lagrangian method——called "Smoothed Particle Hy drodynamics" (SPH) method. The method is to actually evaluate spatial gradients without the use of any grid. Thus it does not suffer form the severe problems always associated with mesh tangling and distortion. Therefore it can be applied to multidimensional hydrodynamics which could effectively model three-dimensional systems which lack symmetry and possess large voids. At first, the paper gives an introduction to theoretical basis to SPH. Emphasis is given to a proper derivation of the SPH equations from the hydrodynamical conservation equations. Discussion covers some relative problems such as artifical viscosity, thermal conduction, self-gravity and sink and magnetic fields, choosing the smoothing kernels, and implementation of SPH code, etc.

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THE THEORY CALCULATION OF THE ATOMIC PARAMETER-FOR NiⅠ-LIKE IONS 3d94s,3d94p AND 3d94d CONFIGURATION Chen Minglun, Li Xiaochang, Yang Xiangdong 1996, 13(4): 398-402.  Abstract ( )   PDF (138KB) ( )   In this paper,the energy level-wavelength and Oscllatar strength for Highly ionized NiⅠ-like ions 3d94s,3d94p and 3d94d configurations are calculated by using multiconfiguration selfconsistent field method together with the fitting formula proposed here. The calculations have a good agreement with observations.

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A SEMI-LAGRANGIAN INTEGRATION SCHEME KEEPING CONSERVATION OF TOTAL ENERGY Ji Zhongzhen, Wang Bin 1996, 13(4): 403-409.  Abstract ( )   PDF (250KB) ( )   One of important features in the numerical modelling of motions of atmosphere or ocean consists in the long period prediction.A key point in such simulations is to maintain the intrinsic physical features of the original problem and to preveant the distortion due to the accumulation of numerical errors.This paper takes into account the traditional Semi-Lagrangian integration scheme.A scheme is constructed so as to keep the conservation of total energy and enlarge the time step to one decade times.Besides it is an explicit scheme,it avoids complex matrices.Several preliminary numerical tests show good perspective of this scheme.

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A PARALLEL IMPLEMENTATION OF AN IMPLICIT TVD FINITE DIFFERENCE ALGORITHM USING THE DOMAIN DECOMPOSITION METHOD Wang Qiang, Ma Handong, Wang Yiyun 1996, 13(4): 410-414.  Abstract ( )   PDF (213KB) ( )   Based on a static non-overlapped domain decomposition method,the problem is studied about the parallel implementation of a Harten-Yee implicit TVD difference algorithm on a MIMD multi-computers parallel system.The convergence and stability of the parallel processing techniques used here are manifested well through numerical simulation of the steady "super-supersonic" jet flow fields,and the parallel parameters obtained are promising.

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EXCITATION COLLISION STRENGTH AND RATE COEFFICIENT OF NI-LIKE IONS BY ELECTRON IMPACT Fang Quanyu, Cai Wei, Shen Zhijun, Zou Yu, Li Ping, Xu Yuanguang 1996, 13(4): 415-420.  Abstract ( )   PDF (267KB) ( )   Electron-impact excitation collision strength Ω(nl-n'l')(3≤n≤7,4≤n'≤7) among configuration-average levels for the Ni-like Ions Pb54+, Au51+,Ba28+,Mo14+,Ge4+ have been calcuated systematically using the quasirelativitic distorted-wave methods. In addition, the collision strength in high limit have been calculated. The data for the collision strength or thermally averaged rate coefficient over the whole range of energy or temperature have been evaluated by a least-squares spline fitting procedure. As a result, the collision strength with arbitrary electron energy and rate coefficient with arbitrary temperature can be determined by ten parameters.

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COMPUTING STEADY SUPERSONIC FLOW FIELDS-BY USING ADAPTIVE STREAMLINE GRIDS Xu Guorong 1996, 13(4): 421-426.  Abstract ( )   PDF (249KB) ( )   A numerical method of computing steady supersonic flow fields by using adaptive streamline grids.The Friedrichs-Lax Scheme is extended to arbitrary quadrilateral grids.during itaration process the streamline positions are computed from streamline equation after the velocity field is obtained.Finally,the high resolution results obtained by the method are shown.

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THE SYNTHEIZED MODEL AND COMPUTER SIMULATION ABOUT STATIC-DYNAMIC-ELECTRICAL CONTACT PROCESS OF MICROSWITCH Li Jianshi, Chen Tianjian, Yang Zhonghui 1996, 13(4): 433-438.  Abstract ( )   PDF (233KB) ( )   In this paper,taking microswitch as type mechanism of openable-closed electromechanical components,on basis of constructing it's finite element model of the quick acting mechanism's static-dynamic process and contact system's electrical contact process.Furthermore,we regard static-dynamic and electrical contact process as a whole by using dynamic model combining static-dynamic and electrical contact model as whole.We have constructed synthesized,have taken AK# microswitch as example,and have given synthesized example of computer simulation.

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KINETIC STUDIES ON THE GAS-PHAS ELEMENTARY REACTIONS IN CVD DIAMOND FILM ENVIREMENT Dong Xialan, Li Yanxin, Sun Jiazhong 1996, 13(4): 439-444.  Abstract ( )   PDF (239KB) ( )   A gas-phase elementary-reaction mechanism of diamond growth by a vapor depostion process is proposed. The rate constants for-all reactions included in the model have been computed using the species and their transition-state parameters predicted by molecular orbital ab intio at HF/6-31G* level The calculated results quantitatively agree with experimental data on the concentration of gas-phase species and substrate temperature.

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ON THE CONSISTENCY OF CONSERVATIVE ALGORITHMS-FOR INTERNAL INTERFACE IN THE SIMULATION-OF INVISCID FLOW BY ZONAL METHOD Tang Hansong, Lee Chunhian 1996, 13(4): 445-453.  Abstract ( )   PDF (323KB) ( )   Conservative algorithms for internal interfaces are investigated for simulations of compressible inviscid flows by zonal methods. Analysis indicates that the conservative algorithm of interpolation type may be inconsistent with governing equations of the flows,and calculations show that this will cause severe numerical errors,and even ruin the stability and convergency of the computed solutions. Therefore, self-adaptive methods are proposed for internal interfaces and numerical examples are also presented.

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NUMERICAL SIMULATION OF OPTICALLY IONISED LI-LIKE NEON PLASMA RECOMBINATION X-RAY LASERS Y F Shao, S J Rose, A Djaoui 1996, 13(4): 454-458.  Abstract ( )   PDF (218KB) ( )   A non-LTE average atom model which has been modified to include tunnel ionisation and ATI heating is presented, and the model is applied to study the optically ionised Li-like Ne recombination X-ray laser. Results from the calculation show that high gain in Li-like Ne at 9.8 nm can be produced with a 100 fsec duration, 0.248μm laser of intensity 2×10-17Wcm-2 and the gas density of 10-3gcm-3. The duration of X-ray lasing is about 1.5 psec.

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TWO KINDS OF DIFFERENCE SCHEMES FOR SOLVING THREE TEMPERATURE EQUATIONS IN LASER- X-RAY CONVERSION Chen Guangnan, Zhang Xinghong, Shen Longjun, You Xiwen 1996, 13(4): 459-465.  Abstract ( )   PDF (262KB) ( )   In order to study physical laws related to laser X-ray conversion, two kinds of difference schemes, i.e.implicit method and splitting scheme, for solving electronic、ionic and photonic temperature equations are presented. The splitting scheme separating the energy exchange term from other terms is introduced and its influence on temperature is also investigated.

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NUMERICAL SIMULATION OF TEARING MODE WITH TOROIDAL COUPLING Peng Dianyun, Xiao Chengxin, Qiu Xiaoming 1996, 13(4): 466-474.  Abstract ( )   PDF (345KB) ( )   Three-point center difference scheme is employed to solve tearing mode equations which have the second-order removing singularity at an interval end and the first-order non-removing sigularity on the rational magnetic surface in the interval. A method of approximately equivalent grids is presented. The numerical simulations of the tearing mode equations with toroidal coupling are done under different safety factor distributions, and give the corresponding link parameters which can determine the stability of the mode, coupling intensity parameters, growing factors. These numerical results show that the toroidal coupling effect in linear stage has a little influence.

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TARGETING AND CONTROLLING OF CUBIC MAP Liu Zonghua, Ni Wansun 1996, 13(4): 475-480.  Abstract ( )   PDF (245KB) ( )   The continous chaos controll has been implemented on a parameter axis for unstable periodic orbits. It can target and control any point in chaotic or bifurcation regions by adjusting parameter and variable perturbation at the same time. The method given in this paper is robust against noise.

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STUDY ON THE FREEZING OF PCM IN ANNULAR SPACE Zhou Jianhua, Chen Mingyong, Chen Zhongqi 1996, 13(4): 481-488.  Abstract ( )   PDF (302KB) ( )   Analytical solutions of the freezing of phase change material (PCM) in annular space are presented. Firstly, approximate integral method and numerical simulation are used to analyze the heat transfer process during the freezing of the PCM in annular space with internal boundary cooled and external boundary insulated.Secondly, a comparison is made between the results obtained by approximate integaral method and the numerical solution. Then, the effects of all kinds of parameters on the freezing process are discussed. Finally, two important conclusions are summarized:1.when the ratio of the inside diameter to the outside one of the PCM is not less than 0.6, we can assume a quadratic temperature distribution in PCM instead of a log arithmic one so as to cut down the efforts used in solving process, and the error will not exceed 1.5%;2. approximate integral method is not apropriate for solving those solid-liquid phase change problems which possess a low Stefan number.

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AN ESTIMATION OF ‖Rp‖∞ AND CONDITION NUMBER FOR ICCG METHOD Lei Guangyao, Huang Chaohui 1996, 13(4): 489-495.  Abstract ( )   PDF (239KB) ( )   Using a model problem and the method of high order approximate LU dicomposition, the preconditioning matrices of ICCG are given and the ‖Rp‖∞ is also estimated. Based on these results, the upper bound of condition numbers of ICCG (s,t) when (s,t)=(1,1),(1,2) and (1,3) are given respectively. For different mesh sizes, the computed results are compared with the theoretical results of this paper.

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INFLUENCE LINE METHOD FOR TRANSPORT PROBLEMS ACROSS THE WALL OF THE NETWORK OF PERMEABLE TUBES Guo Zhongsan 1996, 13(4): 496-500.  Abstract ( )   PDF (188KB) ( )   This paper introduces the "influence line method" which combines analytical method and finite element method.It is helpful in the computation of large scale mathematical model with distributed parameters in concern with transport problems across the wall of the network of permeable tubes.

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HAMILTONIAN FORMALISM OF AN INTENSE FIELD MODEL Wu Chengxun, Ding Peizhu, Chen Zhi 1996, 13(4): 501-504.  Abstract ( )   PDF (175KB) ( )   The canonic equations of an intense field model are constructed by substituting symmetric difference quotient for partial derivative in Hamiltonian and the numerical solution is found by using square-preserving and symplectic scheme.The result is consistent with theoretical analyses,and shows that the method is successful.It probably overcomes the difficulties that often encountered to intense field model by using conventional difference methods.

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PRELIMINARY ANALYSIS OF CITATION FOR CHINESE JOURNAL OF COMPUTATIONAL PHYSICS Zheng Yuxing 1996, 13(4): 505-508.  Abstract ( )   PDF (148KB) ( )   The citation number,citation Language kinds and citation types are analysed for Chinese Journal of Computational Physics published during 1990-1994,the dependace of citation on time is discussed,the half-life period of citation is obtained as well.