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25 December 1984, Volume 1 Issue 2 Previous Issue    Next Issue

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A IMPROVED ADI SCHEME FOR SOLVING NAVIER-STOKES EQUATIONS LU ZHANG-NING 1984, 1(2): 125-132.  Abstract ( )   PDF (421KB) ( )   ADI method is often used to calculate imcompressible Navier-Stokes equations[1]. In the ordinary ADI method, the nonlinear con-vective terms and noslip condition are delayed and streamfunction-vorticity Navier-Stokes equations are uncoupled. So it can't keep comlete two-order accuracy and complete implicit. In this paper, a "alternating linearize" technique for the nonlinear terms is presented, so streamfunction-vorticity Navier-Stokes equations can be coupled and boundary points and inner points are simultaneously solving.This method seems to keep complete two-order accuracy. It is utilized to calculate the "two-dimensional cavity" flow problem at Reynolds number 1, 10, 100, 500, 1000 and 2000. The result shows that the improved ADI scheme has the advantage of unimproved one.

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THE GENERAL TECHNIQUES FOR MONTE CARLO SIMULATION OF THE MASTER EQUATION ZHANG XIAO-ZE 1984, 1(2): 133-143.  Abstract ( )   PDF (525KB) ( )   The present paper discribes the general techniques for the Monte Carlo simulation of the master equation. The Monte Carlo simulation is considered for the difference solution of the master equation under the condition of the general transition rate form. The integral equation with a transient source term is established, which is equivalent to the master equation initial problem. Thus, the more general techniques are presented for the simulation of the master equation.

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TYPE DEPENDENT SPLITTING METHOD FOR MIXED-TYPE DIFFERENTIAL EQUATION OF TRANSONIC FLOW LUO SHI-FENG 1984, 1(2): 144-151.  Abstract ( )   PDF (459KB) ( )   In Computing steady transonic blow, the governing equation is of mixed type.In most part of the computed region, it is of ellip-tic type; while in a region to be determined,it is of hyperbolic type.In this paper, we discuss the relationship between steady equa-tion and tim-dependent equation.On the basis of an analysis based on Jameson's characterstic theory we propose two time-dependent equations and defferent type-dependent splitting methods..Finally we apply these equations and splitting methods to solve transonic small-disturbance equation.Numerical resurts indicate that the me-thod is simple、reliable and converges rapidly.

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SOLUTION OF REACTOR NEUTRON DIFFUSION EQUATION IN THREE-DIMENSIONAL REGION USING IHE SIP AND SSIP YANG YING-HUI 1984, 1(2): 152-163.  Abstract ( )   PDF (634KB) ( )   In this paper, fist'we discribe briely neutron diffusion equation in three-dimensional segion, establishment of its finite difference equation and inner and outer iteration procedures. Then we derive in detail the SIP (Strongly Implicit Procedure) and SSIP (Symmetrical SIP) for solving finite difference equation in inner iteration procedure, accelerated method for inner and outer iteration and selection of iteration parameters. Finally, some results of nummerical experiment are presented.

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SOLUTIONS OF REACTOR TRANSIENT EQUATIONS IN THREE-DIMENSIONAL REGION BY IMPROVED QUASISTATIC METHOD SHAN WEN-ZHI, JING XING-QING, GU LI-ZHEN, WANG ZI-QING, ZHAO ZHI-YUAN 1984, 1(2): 164-175.  Abstract ( )   PDF (690KB) ( )   This paper describes the improved quasistatic method for solving reactor transient equations in three-dimensional region.Two transient problems are calculated, and results are compared with these by traditional direct numerical difference methods.For TWIGL problem the maximum error of power is 1.57%, for CANDU reactor model, near maximum power point, the maximum error of thermal neutron flux is 0.88% in comparing with the reference solution, hence the results are satisfactory the advantage of saving computation is demonstrated.

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MACH WAVE FORMED AS A PLANE SHOCK WAVE PASSED DOWN A BACKWARD STEP HUANG WEN-SHENG, LIU KE-QI HU, YONG-SHENG, LI ZHI-NIAN, LI YIN-FAN, CAO YI-MING 1984, 1(2): 176-186.  Abstract ( )   PDF (1016KB) ( )   As a plane shock wave with shock mach number Mi propagates down a backward step of height H (fig 1) a part of the shock front turns to be curvilinear It reflects from the horizontal part behind step.This unsteady regular reflection eventually becomes Mach reflection.We present here the results of shock tube experiment (Mi ≤ 2.20) and numerical simulation of this phenomena, say the transition from regular reflection (RR) to Mach reflection (MR).The dependence of the position of transition Lk and critical angle of transition ωCk on strength of the impinging plane shock Mi and height of step H are analysed.Our experimental and numerical results are compared with the theoretical criLerion of transition of Iton & Itaya[15].It should be mentioned that the numerical method of FLIC type with triangular mesh developed in[13] is successful.

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SELF-CONSISTENT LMTO APPROACH TO THE ELECTRONIC STRUCTURE OF SEMI-CONDUCTORS:αSn AND CdTe HAN RU-SHAN, A. J. FREEMAN 1984, 1(2): 187-199.  Abstract ( )   PDF (752KB) ( )   The self-consistent Linear Muffin Tin Orbital (LMTO) energy band method is applied to the case of the open structures:Sn(Diamond) and CdTe (Zinc blende). Empty spheres are inserted into the most open parts of the structure and each sphere is assigned a spherically symmetric potential.Using Orthogonal Experimental Design(OED)method for determining the radii of the overlapping atom spheres and empty spheres, the resulting band structure are presented. Good agreement with band results of pseudopoten-tial methods as well as with experiment is found.

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THE ELECTROSTATIC WAVE SPECTRAL RESPONSE OF PLASMA PARTICLE SIMULATION LIU CHENG-HAI, WANG MIN 1984, 1(2): 200-211.  Abstract ( )   PDF (629KB) ( )   Plasma particle simulation wave spectral response to electrostatic wave is systematically analyzed. We introduce the wave spectral-response function of plasma particle simulation.The response expre-sion in following case is derived respectively, Finite-Size-Particle with Gauss, triangle and square shape, its dipole expansion near grid point, finite difference and FFT solving process of Poisson equation. The influence of shape, size and treatment of Finite-Size-Particle, space discreteness and solving process of Poisson equation on particle simulation spectral response and the depression of short wave noise are discussed.

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A NEW MONTE CARLO METHOD FOR MULTIGROUP ADJOINT INTERGRAL EQUATION OF NEUTRON FLUX HWANG QI-GIN 1984, 1(2): 212-225.  Abstract ( )   PDF (743KB) ( )   Adjoint Monte Carlo Method possess especial superiority for cal-oulating the point flux or radiation environment problem, while the other methods do not possess so far. However, the variance of adjoint Monte carlo method is always large.In this paper we present a new method with reduced variance for multigroup adjoint intergral equation of neutron flux, Namely the method of "the best" changed factor of weight, The calculations show that this method can reduce the variance remarkably.

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A METHOD FOR SOLVING THE NONLINEAR NEUTRON TRANSPORT EQUATION DU XIANG-WAN 1984, 1(2): 226-236.  Abstract ( )   PDF (634KB) ( )   In this paper the nonlinear neutron transport equation is derived. The collisions between neutrons are taken into account in this equation. In order to solve this equation we proposed the successive n-n collision expansion method.By using this method the equation is deduced to the form suitable for numerical computation. The numerical calculation is performed and the significance of the solution is discussed.

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NUMERICAL SOLUTION OF SATURATED-UNSATURATED SEEPAGE FLOW UNDER RAPID CHANGE OF THE WATER SURFACE LEVEL LEI GUANG-YAO, ZHANG SUO-CHUN, GAO JI 1984, 1(2): 237-244.  Abstract ( )   PDF (527KB) ( )   The implicit alternating-direction-iteration method is used to solve question of saturated-unsaturated seepage flow under rapid change of the water surface level. The numerical.results of Akai model are given and compared with experimental results.It is found that the numerical results given in this paper are in good agreement with experimental results and better than results by finite element method.The numerical results of komada model are close to results by finite element method.

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EFFICIENCY PREDICTION TO THE MONTE CORLO METHOD XU SHU-YAN 1984, 1(2): 245-252.  Abstract ( )   PDF (428KB) ( )   In comparing any two kinds of Monte Corlo method used in the particle transport problem, the sufficient condition increasing the collision numbers is given in this paper the integral equations satisfied by each of quantities, which are present in efficiency ration of any two kinds of Monte Corlo method, are discribed.For the simplified models, efficiencies of some ordinary Monte Corlo method are predicted.the calculation results show that the predictive results agree well with numerical results.

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CALCULATION OF THE THERMAL NEUTRON SCATTERING LAW USING THE METHOD OF FOURIER TRANSFORM HU YONG-MING, ZHONG WAN-FA 1984, 1(2): 253-258.  Abstract ( )   PDF (351KB) ( )   Some of the features and problems involved in the thermal neutron law code RSLT-1 which is based on the method of Fourier transform are discussed. The analyses of the calculated results of some actual moderators are presented.