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25 July 1998, Volume 15 Issue 4 Previous Issue    Next Issue

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A NEW AND ACCURATE FREE SURFACE SCHEME IN 1-D AND 2-D NUMERICAL CALCULATIONS OF ELASTIC-PLASTIC FLOW Zhou Nan, Cheng Shuyu, Chen Yusheng, Ding Sheng 1998, 15(4): 385-392.  Abstract ( )   PDF (285KB) ( )   A new free surface scheme for 1-D and 2-D numerical calculation of elastic-plastic flow is proposed to study e-beam or X-ray radiation,high velocity impact and blast.Some numerical examples given here show that the pressent free surface scheme is more suitable than Richtmyer's for solving thermal-mechanical effects of material subjected to e-beam or X-ray pulse radiation.It is proved that this scheme should give a third-order accuracy.

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NUMERICAL SIMULATION OF THE THREE-TEMPERATURE FREE-PATH FOR NON-LTE Al PLASMA Han Guoxing, Li Shichang, Wu Zeqing 1998, 15(4): 393-396.  Abstract ( )   PDF (190KB) ( )   The mean-free-path for photon energy flux is calculated with the three temparature model in the NON-LTE system;The electron occupation probabilities Pi are obtained by solving the rate equations;The results of numerical simulation for aluminum plasma are given with comparision and discussion.

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Further Study to a One-Dimensional CI Transition Model Xu Aiguo, Wang Guangrui, Chen Shigang, Zhang Guangcai 1998, 15(4): 397-402.  Abstract ( )   PDF (249KB) ( )   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).

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THE STUDY OF MECHANISM FOR THE AMPLIFICATION OF BACKGROUND VORTICITY IN VORTEX RECONNECTION Wang Weiguo, Shi Changchun, Chen Yaosong 1998, 15(4): 403-408.  Abstract ( )   PDF (276KB) ( )   By direct numerical simulation of Navier-Stokes equations the reconnection of two anti-parallel vortex tubes has been studied in terms of the pseudo-spectral method.The influence of different disturbances for initial vortex tubes on reconnection is observed. "Curved vortex belts" are found,and the physical mechanism for the amplification of background vorticity is also investigated.

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NUMERICAL SIMULATION FOR LASER-TARGET NONEQUILIBRIUM COUPLING Chen Guangnan, Chang Tieqiang, Zhang Jun, Zhang Xinghong, Pei Wenbing, You Xiwen 1998, 15(4): 409-418.  Abstract ( )   PDF (372KB) ( )   Main processes involved in the laser-target coupling are described,including the absorption of laser light,heat conduction of electron,plasma motion,nonequilibrium ionization,laser X-ray conversion and the radiation transport.It outlines the numerical simulation,presenting the partial differential equations,constructing the finite difference schemes and describing the solving methods.Finally,some calculated results are given.

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DYNAMIC NUMERICAL SIMULATION OF THE OSCILLATING FLOW IN A PULSE TUBE REFRIGERATOR Ju Yonglin, Wang Chao, Zhou Yuan 1998, 15(4): 419-428.  Abstract ( )   PDF (387KB) ( )   It describes an improved numerical model and calculation method for stability simulation of a pulse tube refrigerator.A set of differential equations based on the conservation of mass,energy and momentum for oscillating fluid flow is solved by numerical method.A variety of physical factors,such as actual gas,gas flow friction,heat transfer in the heat exchanger and regenerator,ect.are included to improve the accuracy of the model.The results show the changes of mass flow,pressure,temperature,enthalpy flow and so on in each cell with time.The computer predicted performance is compared with the experimental data.Good agreement has been found between the two.

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Synchronization of Hyperchaos Liu Zonghua, Chen Shigang 1998, 15(4): 429-434.  Abstract ( )   PDF (238KB) ( )   A novel approach is proposed for synchronizing hyperchaotic systems. It is achieved by adjusting the parameters of response system. The variation of parameter can be determined by using of the Routh-Hurwitz stability criterion. As a general method of synchronization, it is robust against external noise.

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PHASE TRANSITION OF THE SHORTEST-PATH AGGREGATION Long Chaoyun, Li Houqiang, Luo Wenfeng, Zhu Zhijun 1998, 15(4): 435-438.  Abstract ( )   PDF (154KB) ( )   The growth probabilities {Pα,i} and configuration weights Cα (for 2×2 cell and 3×3 cell) are obtained by using the renormalization-group method. The "partition function" Z(q,L), "Free energy" F(q,L),"energy" E(q,L),"specific heat" c(q,L) and hierarchical dimensions Dq are calculated. The evidence has been found for suggesting the existence of phase transition in the multifractal spectrum of the SPA model and position of critical point qc=0. In the words, the distribution of growth probability has no multifractal features.

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A THERMODYNAMICS LATTICE-BOLTZMANN METHOD MODEL Xiong Shengwu, Li Yuanxiang, Kang Lishan, Chen Juhua, Ruan Jian 1998, 15(4): 439-444.  Abstract ( )   PDF (274KB) ( )   A thermodynamic lattice Boltzmann model whose equilibrium distribution function include high order terms of velocity and internal energy terms is presented, and a new kind of implement of gravity and temperature boundary is also proposed by which thermodynamics phenomenon permits to be simulated. Based on the HPP model, a three-overlapped HPP lattice Boltzmann model is introduced. The Benard pattern of thermal convection phenomenon has been simulated successfully by using this model on SUN workstation computer.

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STUDY ON STRUCTURES AND THERMOELECTRICPROPERTIES OF BORON CARBIDE, PHOSPHIDE AND ARSENIDE Min Xinmin, Cai Kefeng, Nan Cewen 1998, 15(4): 445-450.  Abstract ( )   PDF (231KB) ( )   The correlation among composition, structure, chemical bond and thermoelectric property of boron carbide, phosphide and arsenide is studied with SCF-DV-Xα method, one of calculation methods of molecular orbital in quantum chemistry. The differences between the three materials are studied. As the P-P and As-As chains have no characteristic of double bond, it is difficult for the boron phosphide and arsenide to transfer electrons, though they have the same structure as boron carbide. The C-B-C and C-B-B chains have the characteristic of double bond, so it is easy for the boron carbide to transfer electrons and hop the bipolarons. Therefore, boron phosphide and arsenide have no characteristic of double bond but boron carbide has, which is the main reason that as their thermoelectric property is too bad, boron phosphide and arsenide are not considered as the thermoelectric materials, but boron carbide has the much better thermoelectric property than boron phosphide and arsenide.

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CALCULATION AND ELIMINATION OF MULTIPOLE POTENTIAL COMPONENTS IN A PRACTICAL Cai Yong, Yan Min, Luo Xueli, Gao Kelin, Zhu Xiwen 1998, 15(4): 451-456.  Abstract ( )   PDF (249KB) ( )   Multipole components of potential field are calculated by using a boundary element method in an RF ion trap, when there exist assembling imperfections and axial holes in the end-caps and a band-cut on the equatorial surface of the ring electrode. The variation of multipole components versus the dimensions of holes and band-cut are analyzed in detail. The calculated results indicate that when specific conditions are satisfied, some non-linear effects can be compensated partially each other and a nearly ideal quadrupole potential can be obtained.

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CORRELATION ENERGY OF DOUBLE ELECTRON SYSTEM OBTAINED BY USING B-SPLINES BASIC SETS Liu Lianjun, Li Long, Zhang Zhehua, Qiao Haoxue, Li Baiwen 1998, 15(4): 457-462.  Abstract ( )   PDF (222KB) ( )   It reports the investigation on calculation methods of ground-state correlation energy of double-electron system atoms (or ions) by using B-splines basic sets. These methods belong to the application category of calculus of variations, and adopt B-splines techniques to account for the radial bases, and at the same time, deal with the angular bases by using Goldman's mixed L method. The calculation results are given for He, H-,Li+,Be++,B+++ atoms (or ions) and compared with those of others' theoratical methods. This comparison demonstrates that our calculation methods have excellent computing accuracy and efficiency.

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ANISOTROPIC CARTESIAN GRID METHOD FOR THE NAVIER-STOKES EQUATIONS Wu Ziniu 1998, 15(4): 463-475.  Abstract ( )   PDF (477KB) ( )   The Cartesian grid method initially developed for computing inviscid flows is extended to viscous flow problems. In order to reduce the number of mesh points and to be compatible with the anisotropic nature of viscous flows, an anisotropic Cartesian grid method is proposed. The stability of a space-centered interior difference scheme and that of a finite-difference solid wall condition are studied for the Cartesian grid. It is found that the anisotropic Cartesian grid method can substantially reduce the number of grid points without jeopadizing the accuracy.

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NUMERICAL SIMULATION OF THREE-DIMENSIONAL HYPERSONIC INVISCID FLOWS OVER SPACEVEHICLES WITH FCT FINITE ELEMENT METHOD Cai Qingdong, Wu Wangyi 1998, 15(4): 476-482.  Abstract ( )   PDF (294KB) ( )   FEM-FCT is used to solve three-dimensional hypersonic inviscid flow.The flow fields around sphere,modified space shuttle orbiter and capsule type vehicle are gained on unstructured tetrahedron grids.The results show that the scheme is valid and has high resolution to shock waves.

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THE ANALYSES OF RAYLEIGH TAYLOR INSTABILITIESFOR SINGLE MODE ON THE SURFACE OF RADIATION ABLATION Zhang Jun, Lai Dongxian, Zhang Weiyan 1998, 15(4): 483-488.  Abstract ( )   PDF (232KB) ( )   The hydrodynamic surface instabilities driven by X-ray ablation in Inertial Confinement Fusion(CIF)have been analyzed,and the role of Raleigh-Taylor(RT) instabilities in CIF has been also discussed.Based on one dimension numerical computational results,according to the formula of net growth factor at the ablation surface,the net growth rates of RT instabilities have been estimated.Finally,some recommendations for instability experiment are proposed.

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A NINE POINT DIFFERENCE SCHEME AND ITERATION SOLVING METHOD FOR TWO DIMENSIONAL ENERGY EQUATIONS WITH THREE TEMPERATURES Fu Shangwu, Fu Hanqing, Shen Longjun, Huang Shuke, Chen Guangnan 1998, 15(4): 489-497.  Abstract ( )   PDF (434KB) ( )   A nine point difference scheme and iteration solving method is presented for two dimensional energy equations with three temperatures, in numerical simulation of driven implosion by laser. Some results are given as well.

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LYAPUNOV SPECTRUM OF THE ATTRACTOR OF THE 5-DIMENSIONAL CONVECTION MODEL Bao Yanchun, Bao Mingtang 1998, 15(4): 498-502.  Abstract ( )   PDF (190KB) ( )   The algorithm of Lyapunov spectrum is applied to calculate Lyapunov spectrum of the attractor and the dimension of the strange attractor of the 5-dimensional convection nonlinear dynamical system.

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MONTE-CARLO STUDY OF ENERGY OF LIQUID WATER IN MAGNETIC FIELD Lu Guiwu, Zhou Kaixue, Chu Jun 1998, 15(4): 503-508.  Abstract ( )   PDF (230KB) ( )   Effect of a magnetic field on potential energy of liquid water are investigated for first time using classical Monte-Carlo computer simulation and a water model L-J. The relationships between energy and magnetic flux density and temperature have been studied by calculating potential energy and radial distribution function (RDF) of a system containing 64 water molecules. Comparisons with the field-off system are made throughout. It is found that the computer simulation is in agreement with experimental results.

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TRANSPORTATION FOR THE THREE DIMENSIONAL ELECTROSTATIC FIELD COMPUTATION SOFTWARE,RELAX3D Zhang Tianjue, Dai Xiaoming, Huang Jijie, Chu Chengjie, Fan Mingwu 1998, 15(4): 509-512.  Abstract ( )   PDF (188KB) ( )   The 3D Electrostatic Field Computation software RELAX3D is developed since the beginning of 70's in TRIUMF,CANADA.It can be run in the VMS and UNIX software environment only.The transportation from VAX/VMS to PC/DOS is described in this paper.Many standard examples have been calculated to confirm the transportation work.An engineering computation,the electric field distribution on the head of 600kV ns pule neutron generator,is described also.