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25 June 1986, Volume 3 Issue 2 Previous Issue    Next Issue

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ON DISCRETE-COLLOCATION METHODS FOR SOLVING THE TRANSPORT PROBLEM WITH TWO-DIMENSIONAL CYLINDRICAL SYMMETRY Du Ming-sheng, You Teng-gao 1986, 3(2): 129-141.  Abstract ( )   PDF (588KB) ( )   Discrete-Collocation method is considered for Solving the neutron transport equation in two-dimensional cylindrical geometry. Conservation and equivalence of the collocation method to the DSN method are derived. Finally, Some numerical results are presented.

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SSS:A CODE FOR COMPUTING ONE DIMENSIONAL SHOCK AND DETONATION WAVE PROPAGATION Sun Cheng-wei 1986, 3(2): 142-154.  Abstract ( )   PDF (731KB) ( )   The one-dimensional hydrodynamic code SSS for shock and detonation wave propagation in inert and reactive media is described in this paper. The elastic-plastie-hydrodynamic model and four burn techniques, the Arrhenins law,C-J volume, sharp shock and Forest Fire are used. There are two options of the equatin of sta te for detonation products:HOM and JWL. Compared with it's reference-the SIN code published by LANL, the SSS code has several new options:laser effects, blast waves, diverging and instantantaneous detonation waves with arbitrary initiatron positions. Two examples are given to compare the SSS and SIN calculations with the experimental data.

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A COMPUTATION OF LOW REYNOLDS NUMBER NON-LINEAR FLOW PAST A BODY Zhang Jun-xiu, Lei Xu-ming 1986, 3(2): 155-160.  Abstract ( )   PDF (370KB) ( )   This paper presents a method of solving low Reynolds number non-linear flow past a body. To be based on Oseen's equation, the effect of non-linear terms is considered by successive iteration. First, we write Navier-Stokes equation as Oseen's equation,with a forcing function (i, e, non-linear terms);then,this equation solution is given by a integral form of the ‘Oseenlet’. It is a non-linear integral-differential equation which involves a body surface integral and a flow space integral. Let distributive intensity of the ‘Oseenlet’ on the surface be unknown. They are decided by the boundary condition. Since the Space integral depends on the flow field which is not known prior to solution, an iterative scheme is used. The iterative process continues until a convergent solution is complete.This method is used to evaluate the drag acting on a single cylinder in uniform flow until Reynolds number Re=10. The obtaining results is-compared with the experimental data and the related results. It indicates that the present method is satisfactory.

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THE SOLUTION OF EM WAVES LOSS THROUSH INHOM-OSENEOUS AND LOSSY PLASMA-SHEATH USING FEM Liu Tie-jun, Shi Zhong-yue 1986, 3(2): 161-170.  Abstract ( )   PDF (596KB) ( )   In this Papar, the reflection and transmission Properties of EM waves incident on a inhomogeneous and lossy plasma sheath with arbirary profile are discussed by using finite element method,The prarameters of profile takes of the fluid fields data of viscus shock layer for a typical re-entry vehicles.Starting from the virtual work principle,first of all,the variational equ-ation of EM propagation throush the plasma sheath is derivated and then the finite element equation is developed from the veriational equation,The element matrix for EM propagation through the plasma sheath with an arbitrary profile is constructed by applying a function of linear interpolation and numerical results are discussed. Our conclusion is that the FEM is suitable for computation of radio waves through plasma sheath with an arbitrary variable profile.

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APPROXIMATE ESTIMATE DENSITY OF ELECTRONS PRODUCED BY NUCLEAR EXPLOSION OF THE HIGH-ALTITUDE Wang Tai-chun, Wang yu-zhi 1986, 3(2): 171-182.  Abstract ( )   PDF (578KB) ( )   Under the nuclear explosion of high-altitude, second electrons are produced by high energy electrons that are produced by γ-compton scater ionizing the atomosphere. In this paper, we deduced the analytic solution of the rate equations discribing second electrons and compared the results of analytic solution with those of numerical solution:the higher the altitude, the nearer the computational results of two methods are.

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A SIMPLE AND CONVENIENT NUMERICAL SIMULATION APPROACH FOR MACH REFLECTION——SPLITTING QUASI-CHARACTERISTIC METHOD Liu Ru-xun, Wei yong 1986, 3(2): 183-193.  Abstract ( )   PDF (553KB) ( )   In this paper a simple and convenient approach for numerical simulaionapproach of Mach reflection——splitting quasicharacteristic method is proposedThe method is adaptable and flexiole, the construction of the schemes of this method is simple and various, the programming is quite easy, and the quantities of the arithmetic operation and the informations are not expensive compared with the others.For example of Mach reflect ion, in the paper,a plane shock wave past wedge is numerically simulated, The computting results show that the contour of Mach reflection and the basical characters of the flow field are satisfactory.

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TCG ITERATIVE METHOD FOR SOLVING SYSTEM OF LINEAR ALGEBRAIC EQUATIONS Chen Tzang-fei 1986, 3(2): 194-206.  Abstract ( )   PDF (672KB) ( )   The method ICCG. is one of the best iterative method for solving the system of linear algebraic equations, but it can only be applied to the symmetric and positive definite coefficient matrix. The TCG method itroduced in this paper is a modified ICCG mothod. It can be applied to the matrices which are non-singular、unsymmetric and not positive definite. For the unsteady problem this method can raise the efficiency by 18 percent as compared with tie ILU.CG method. In particular if we take the SIP incomplete L、U decomposition as the preconditioned method, TCG method can raise the efficiency by 40 percent. It is indeed a bast iterative method applied to the matrices which are unsymmetric and not positive definite. In this paper we deduce the TCG method with the elimination method as the incomplete L、U decomposition and use the computational results to indicate the reason why the TCG method converges more quickly than ILUCG method.

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ERROR ANALYSIS OF THE QZ ALGORITHM Dong Hao-zhe 1986, 3(2): 207-216.  Abstract ( )   PDF (460KB) ( )   Error analysis of the QZ algorithm for Solving fhe eigenvalue of a matrix pencil of the type λB-A is ginen in the paper The paper is made up of two parts In the first part we estimated the number of transformation of QZ algorithm.In the second one the formula of estimate of error is given.

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A DIMENSIONAL REDUCTION METHOD FOR INCOMPRESSIBLE FLUID DYNAMICS Ⅱ.THE BASIS OF V~h AND THE ERROR ESTIMATES Yu Xin 1986, 3(2): 217-226.  Abstract ( )   PDF (589KB) ( )   This paper is the second in a series of papers in which we present a new finite element method for incompressible fluid dynamics-a dimensional reduction method. In this paper, we give a simple basis of Vh for a class of finite element schemes for solving Navier-Stokes equations in a bounded domain Ω⊂R2, discuss how the numerical error of the velocity field affects the numerical solution of the pressure, and present an improved algorithm.

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NUMERICAL METHOD FOR THREE-DIMENSIONAL UNSTEADY FLOW Liu Bang-di 1986, 3(2): 227-233.  Abstract ( )   PDF (396KB) ( )   In this paper a finite d if ference code for three dimensional unsteady flow has been provided.It is a Lagrangean method.we have constracted a ic-osotetrahedron. we have integrated the equation of momentum over the icosot-etrahedron and estaklished the difference equation.It is simple and easy to calculate

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A MODIFIED DENNIS SCHEME FOR THE STEADY-STATE CONVECTION-DIFFUSION EQUATION Lu Jin-fu, Guan Zhi 1986, 3(2): 234-240.  Abstract ( )   PDF (358KB) ( )   In this paper, A modified Dennis scheme for the steady-state convection-diffusion equation is proposed. Elementry analysis and numerical computation for model problem show that, the highly inaccurate behaviour of Dennis scheme is corrected by modified Dennis scheme.

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THREE DIMENSIONAL INTERAL ELECTROMAGNETIC PULSE CALCULATED BY PRATICLE SOURCE METHOD Wang Yu-zhi, Wang Tai-chun 1986, 3(2): 241-248.  Abstract ( )   PDF (412KB) ( )   In this paper, the numerical results of the primary electronic current and the internal electromagnetic pulse were obtained by particle method in the cavity of three dimensional rectangle.We compared those results with the results calculated by three dimensional Euler-method. Under the same conditions, the results obtained by particle method agree with results by Euler-method.

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THE MODEL STUDY OF THE SCALE FACTOR APPROXIMATION OF THE AMPLITUDE REDUCTION FACTOR IN THE EXAFS DATA ANALYSIS Zheng Yu-hua, Zhong-Yi 1986, 3(2): 249-254.  Abstract ( )   PDF (398KB) ( )   By Model Calculations, the effects of the scale factor approximation of the amplitude reduction factor on the structural parameters determinations of the crystalline and amorphous material, in the curve-fitting analysis of the EXAFS data have been.studied,and the methods of solving the problem have also been discussed.