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25 June 1990, Volume 7 Issue 2 Previous Issue    Next Issue

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NUMERICAL SIMULATING THE BOUNDARIES OF RECTANGULAR OIL AND GAS RESERVOIR WITH METHOD OF WELL-TESTING BUILD-UP Zhou Hong, Wu Shengchang, Yu Qihuang 1990, 7(2): 129-135.  Abstract ( )   PDF (371KB) ( )   In this paper, we study the analysis solution for the problem of rectangular oil and gas reservoir with boundaries of different types. We can estimate the boundaries location of reservoir by using the methods of numerical simulation and optimization.

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ELECTRON-ION IMPACT EXCITATIONCALCULATION IN COULOMB-BORN APPROXIMATION Fang Quanyu, Cai Wei, Ji Wengui, Qiu Yubo 1990, 7(2): 136-142.  Abstract ( )   PDF (412KB) ( )   This paper briefly describes the theoretical deduction of the cross section of electron-ion impact excitation in Coulomb-Born approximation. The LS coupling representation of electron-ion system is used, the exchange effect is taken into account and the angular factors of collision matrix elements are treated in detail. The corresponding code-CBX(9) is programed. The situations of complex ions and incident electrons with lower energy can be computed by the code, which has wide applicability. The computational results are in well agreement with ones obtained from the other methods.

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THE DOUBLE EQUATIONS METHOD OF DIFFERENCE-BOUNDARY ELEMENT TECHNIQUE FORHEAT PROBLEM Xuan Qiwo, Yang Haito, Wu Ziqian 1990, 7(2): 143-152.  Abstract ( )   PDF (548KB) ( )   The elliptic type equation-Δu+k2u=f (1) is derived from heat conduction equation by finit difference discreting. The ordinary boundary integral equation of (1) is of the second kind for the unknown potential, but is the first kind for the unknown exterior normal derivative of potential. In this paper, a new type of boundary integral equation has been derived by conservation integral method, which is of the second kind for the unknown exterior normal derivative of potential and is the frist kind for the unknown poential, and the two equations method for the mixed boundary value prblem of (1) is presented, which use the ordinary boundary integral equation at the collocation points in the boundary segment in which the potential is unknown, and use the new type of boundary integral equation at the collocation points in the boundary segment in which the exterior normal derivative is unknown. Some numerical examples indicate this method has higer accuracy than ordinary boundary element method.

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SPEED OF SOUND IN ASYMMETRIC NUCLEAR MATTER WITH SG Ⅱ-TYPE INTERACTIONS Zheng Guotong, Shen Xuee, Su Rukeng 1990, 7(2): 153-158.  Abstract ( )   PDF (377KB) ( )   The speed of sound in asymmetric nuclear matter with SG Ⅱ-type potential (including SG Ⅱ and RATP potential) is calculated. We find that the spin exchange part of SG Ⅱ-type potential cannot avoid the difficult of superluminosity. The effect of finite-range force fot the speed of sound is very small. The violation and the restoration of causal condition are discussed.

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THE FOURIER PSEUDOSPECTRAL COLLOCATION METHOD APPLIED TO BORNDARY INTEGRAL EQUATIONS OF THE FIRST KIND Zheng Jeadong, Cheng Nan 1990, 7(2): 159-167.  Abstract ( )   PDF (527KB) ( )   In this parper we present a Fourier pseudospedctral collocation method for boundary imtegral equations of the first kind with a sogarthmec kernel. The diseretr equations are obtained by pseudospectral imterpolation of the symbol assoceated to the integral operator. the cocputations are executed in frequency space by fast fourier travsform. The results show that the numerical accuracy of the pseudospectral collocation cethod are more satisfactry than the Galerkin cillcation ceghod.

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A PRELIMINARY STUDY OF 3-D PRECONDITIONING METHOD Lei GuangYao 1990, 7(2): 168-178.  Abstract ( )   PDF (657KB) ( )   A method of high order approximate LU decomposition is adopted to give the preconditioner for the coefficient matrix of 3-D elliptic partial differential equation when the normal 7-point scheme is used. Numerical results of the preconditioned conjugate gradient (PCG) solving a tipycal problem are given.The concepts of the order, the order matrix and the P-order influence areas given in this paper can be applied to a general sparse non-singular and diagonally dominant linear system of equations. The results of different meshsize show that 3-D PCG has a superlinear convergence rate. In the case of higher orders the superlinearity of the PCG convergence rate is stronger even more. Since the number of non-zero diagonals in the preconditioner increases rapidly when the order of the PCG method increases, it is not beneficial to use the preconditioner of order P if P is larger than one. The preeonditioners of order zero and order one are recommended.

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A KIND OF FINITE ANALYTIC METHODS FOR SOLVING CONVECTION-DIFFUSION EQUATIONS Lu Junan, Shi Gang 1990, 7(2): 179-188.  Abstract ( )   PDF (581KB) ( )   In this paper a kind of Finite Analytic Methods is derived and applied on convection-diffusion equations. These qualities proved are existence, uniqueness, absolute stability and convergence of solutions of finite analytic scheme of linear equations, so are existence, uniqueness and generalized weak stabability of solutions of finite analytic scheme of Burger's equation. Numerical experiments show that the finite analytic scheme is very effective, especially numerical solutions arc not oscillating.

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NUMERICAL ANALYSIS ON A TURBULENT JET IN CROSSFLOW Fong Chingzhen 1990, 7(2): 189-199.  Abstract ( )   PDF (626KB) ( )   A new method is presented here for solving three-dimensional velocity field of a turbulent jet in a cross flow. Taking curvilinear coordinate system in order to fit the jet better, we assume that the second order partial derivetives along the jet axis can be neglected, and the pressure axis gradient of a point in a cross section can be replaced by the axis gradient of the average pressure over this cross section, thus the basic equations become parabolic. We can solve these equations section after section, i. c. we reduce a three-dimensional problem to a series of two-dimensional problems. It makes the a mount of computations decreased greatly, and all computations can be accomplished in a micro-computer. This method is applicable for the case in which the cross wind is not strong.

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THE SIMULATION AND 3-D GRAPHIC DESCRIPTION OF THE INTENSITY DISTRIBUTION OF DIFFRACTED LIGHT BY A SINGLE-SLIT Rang Qinglan, Zhu Wansen, Yan Xinqing 1990, 7(2): 200-204.  Abstract ( )   PDF (321KB) ( )   The spatial distrilution of the diffracted light intensity of a single-slit are simulated and are demonstrated by a 3-dimensional diagram.The law of diffracted light distribution are studied.The connection and boundary of Fraunhofer diffraction and Fresnel diffraction are analysed.

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MONTE CARLO SIMULATION OF SPUTTERING OF TWO-COMPONENT MULTI-LAYER DYNAMIC TARGETS Shao Qiyun, Pan Zhengying 1990, 7(2): 205-210.  Abstract ( )   PDF (404KB) ( )   A Monte Carlo computer program simulating the sputtering of two-component multi-layer dynamic target is presented, including principle, physical models, program design and applicability. The atomic scattering is governed by the Moliere approximation to the Thomas-Fermi potential and is evaluated with the binary-collision approximation. The target is treated in slab geometry, and the thickencss and the target composition of each slab can be rearranged during sputtering.This program can be used to calculate sputtering yields of two-component amorphous target and, therefore, to study preferential sputtering, energy and angular distributions of sputtered species as well as the depth of origin of the sputtered particles in solid target. Some calculation results are given in this paper.

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ADVANCES IN FREE-LAGRANGE METHOD Wang Zixiu, Li Hua 1990, 7(2): 211-227.  Abstract ( )   PDF (1045KB) ( )   Free-Lagrange Method is a new attempt to simulate two dimensional compressible flow with large distortion. It gives up the restraint usually required in traditional Lagrangian method to make fixed connectivity among cells. In FLM the neighbor relation among notes is tested and revised in each cycle, therefore adapti flow distortion naturally. In addition we have made special treatments for free surfaces and interfaces. The application of FLM to hydro-elastic-plastic flow proves to be satisfactory.

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A PARTIAL BROYDEN METHOD AND ITS APPLICATION TO THE DISCRETIZED fpT EQUATIONS Wang Yuanzhang 1990, 7(2): 228-234.  Abstract ( )   PDF (436KB) ( )   In this paper, for a class of nonlinear system of equations #br#F1x1,x2=0#br#F2x1,x2=0#br# we formulate a partial Broyden method. The basic idea is that the relation of x1 to x2 is determined by the first subsystem of equations F1=0, then the Broyden method is applied to the second one F2=0, thus forming a iterative procedure.The application of partical Broyden method to discretized fpT equations is described and numerical results is given.

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NUMERICAL CALCULATIONS OF STOPPING POWERS AND ENERGY STRAGGLINGS FOR IONS IN A STRONGLY COUPLED DEGENERATE ELECTRON GAS Wang Younian, Ma Tengcai 1990, 7(2): 235-240.  Abstract ( )   PDF (330KB) ( )   The stopping powers and energy stragglings for implanted ions in strongly coupled degenerate electron gas were investigated using local-field correction dielectric function.The numerical results have shown thst the stopping powers and energy stragglings were considerably increased due to local-field correction at low volecities and high valuse rs.

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NUMERICAL SOLUTIONS OF ONE DIMENSIONAL STEADY FLOW OF VAN DER WAALS GAS Min Saijin, Li Xiuying, Luo Shijun 1990, 7(2): 241-249.  Abstract ( )   PDF (556KB) ( )   The parameters of one dimensional steady flow of a Van der Waals gas in a nozzle of variable cross section A(x) for isentropic and thermostatical expansion flow are obtained by numerical methods in this paper. The solutions are compared with the theorical solutions of pefect gas and the deviations of the Mach number, density, pressure and temperature ratios are obtained. The obtained conclusions is significative for directing the development of technology of cryogenic and hypersonic tunnels, and the design for rocket engine.

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A REDUCE APPROACH TO ONE DIMENSIONAL POLYNOMIAL ANHARMONIC OSCILLATORS Chen Zhijing, Kong Fanmei, Han Chunjie, Zhao Xueqing 1990, 7(2): 250-255.  Abstract ( )   PDF (365KB) ( )   A REDUCE program based on the two step approach is developed to solve the Schrodinger equation with polynomial potential. The program is very simple and suitable to be carried out on microcomputer, The transformation for Hamiltonian, the obtaining of matrix elements, the derivation of the equation which must be satisfied by the parameter in variation method and even the Fortran program for numerical calculation are all completed or generated by computer automatically, As an example the pure quartic oscillator is calcuated and the results are compared with those available in literatures, Agreements are excellent.