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25 January 1998, Volume 15 Issue 1 Previous Issue    Next Issue

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SIMULATION OF SHOCK WAVE BY THE LATTICE-BOLTZMANN METHOD Nie Xiaobo 1998, 15(1): 1-5.  Abstract ( )   PDF (197KB) ( )   The lattice-Boltzmann method has been applied to simulate fluids.The most are incompressible fluids.This method is used to simulate the transform and regular reflection of shock waves with 3 speeds and 9 sits models on the square lattice.The simulation results is consistent with the results of the fluid equations derived by the Chapman-Enskog expansion.This shows that the lattice Boltzmann method can simulate compressible fluids.

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GENERATION OF UNSTRUCTURED GRID AND TECHNIQUE OF AUTOMATIC REFINE Su Mingde, Zhu Fanglin 1998, 15(1): 6-12.  Abstract ( )   PDF (298KB) ( )   A technique to generate unstructured grids in arbitrary 2D region is presented depending upon the new idea to smooth the grid scale,which gives new explanation of filtered Laplace operator.Choosing appropriate relaxation factor,the iterative number in smooth process max be reduced greatly.The automatic refine of grid is developed and it can be used in adaptive process.The numerical examples show efficients of the present methods.

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COMPARISONS BETWEEN DIFFERENT NUMERICAL METHODS FOR CALCULATING CFP OF NUCLEONS Chen Jianhua, Li Xiaomei, Du Huixian 1998, 15(1): 13-18.  Abstract ( )   PDF (296KB) ( )   Four numerical methods for calculating coefficients of fractional parentage(CFP) of nucleons are compared,and the results show that the method of complete space by neutron-proton couplied is much better than that of over complete space,the method of factorization by group chains is much better than that of non factorization,and there are great differences of calculating amonut between different methods.

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NUMERICAL INVESTIGATION OF NATURAL CONVECTION FOR NON-NEWTONIAN FLUIDS OVER A VERTICAL FLAT PLATE Li Guangzheng 1998, 15(1): 19-28.  Abstract ( )   PDF (355KB) ( )   Laminar free convection heat transfer of non-Newtonian power law fluids over a vertical flat plate has been studied.It is a problem of nonlinear two point boundary values.The two-system of partial differential equations for velocity and temperature are coupled and nonlinear. Three numerical methods are also used to calculate the problem.The effects of Prandtl numbers(Pr) and various flow indexes on convection heat transfer(Nu) have been discussed and the calculations are compared with each other and with the results of other papers.

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THE GENERAL FORM OF CONDUCTION DIFFERENTIAL EQUATION OF ANISOTROPIC RIGID BODY Yang Benluo, Zhang Zizhan, Kong Xianggian 1998, 15(1): 29-34.  Abstract ( )   PDF (223KB) ( )   This paper gives in tensor the general form of conduction differential equation of anisotropic rigid body with changeable physical property.It discusses some relevant problems.It also gives the analysis of computation of anisotropic conduction in general boundary conditions.

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PARALLEL MULTIGRID PRECONDITIONED CONJUGETE GRADIENT METHODS FOR INTERFACE PROBLEMS Mo Zeyao, Li Xiaomei, Zhang Baolin 1998, 15(1): 35-42.  Abstract ( )   PDF (291KB) ( )   Four different types of serial multigrid preconditioned conjugate gradient algorithms are applied to treat interface problems, and their numerical convergence rates are also compared with respect to interface types, interface degree and stepsize. Schwarz parallelism is used for algorithms, and discussion concerns the convergence rates with respect to the number of subdomains, and the benefits owing to Schwarz parallelism. Detailed performence results are also given.

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ONE-DIMENSIONAL SIMULATIONS OF Z-PHICH ELECTROMAGNETIC IMPLOSION PLASMA Yang Zhenhua, Tian Shihong, Wu Yupu 1998, 15(1): 43-47.  Abstract ( )   PDF (205KB) ( )   The generation of pulsed high-energy-density plasma by electromagnetic implosion of cylindrical gas shell (i.e.,hollow Z pinches)has been investigated theoretically using a one-dimensional code proposed here.The main mechanism of EM implosion process involves hydrodynamics,radiation in the collapsing plasma,and equation of LR circuit.The discrepancy between the numerically computed results and the experementally measured results is found to be less than 10%.It is shown that this code can be used as a tool to design new EM implosion device.

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SIMPLE SIMULATION ON THE PROPAGATION PROCESS OF X RAY LASER IN PLASMA Li Yingjun, Xu Aiguo, Peng Hansheng, Lin Bin, Yang Shangjin 1998, 15(1): 48-52.  Abstract ( )   PDF (226KB) ( )   By virtue of a simplified model of gain region, the propagation and amplification of soft-x-ray within the plasma with linear electron density profile are studied in the geometrical optics approximation. A simple formulation evaluating the deflection and divergence angles and the maximum x-ray intensity are obtained. The results are in better agreement with experimetally measured data and numerically simulated results.

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SELECTION OF RELAXATION FACTOR AND CONVERGENCE RATE FOR D-N DOMAIN DECOMPOSITION METHOD OVER UNBOUNDED DOMAIN Yu Dehao 1998, 15(1): 53-57.  Abstract ( )   PDF (184KB) ( )   The selection of relaxation factor plays a key role in D-N domain decomposition methods (DDM). Based on the natural boundary reduction, the D-N DDM for elliptic problems over unbounded domain is discussed. A simple and convenient approach to selection of relaxation factor is given, and an optimal convergence is obtained.

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DISTRIBUTION CALCULATION FOR IMPURITY LEAKED FROM FIRST WALL Gao Xinghua 1998, 15(1): 58-64.  Abstract ( )   PDF (270KB) ( )   The distribution in the plasma of coolant-Helium impurity leaked from the first wall has been calculated and numericall results have given. The peak of the distribution is within the scrape-off layer (SOL). When Helium comcentration at the plasma center is required to be less than 5 percents, permitted Maximum-Leak-Rate (MLR) Nmax is about 0.35×10-3 mol/s and the biggest flaw allowed is with the length of about 3.1mm and the width of 0.63 mm. The main factors effecting the impurity distribution and concentration are such as the temperature and density at the edge of plasma, the temperature and density scrape-off lengths in SOL and the wall temperature.

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AN UPWIND FEM SCHEME FOR ELECTROMAGNETIC FIELD PROBLEM IN MOVING CONDUCTOR Shen Min, Deng Kang, Yang Linghui 1998, 15(1): 65-70.  Abstract ( )   PDF (281KB) ( )   The governing equation of electromagnetic field in moving conductor is of convective-diffusive type. To suppress the spurious oscillations which occur in its Galerkin FEM solution when the grid Peclet number is greater than one and to avoid an inappropriate treatment of diffusive term by Heinrich's upwind scheme, a modified upwind scheme of Heinrich's type is proposed. The scheme is applied to FEM analysis of several electromagnetic field problems in moving conductor.

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APPLICATION OF OPTIMAL CONTROL THEORY TO MAKING GAS-CYCLING DECISION OF CONDENSATE RESERVOIR Ye Jigen, Qi Yufen, Fang Yisheng 1998, 15(1): 71-76.  Abstract ( )   PDF (229KB) ( )   A new method to investigate optimal development decisions of gas-cycling in condensate reservoirs is presented. It is shown that both the oil recovery and the total net present value of a condensate reservoir can be enhanced obviously through optimization of gas production rate, gas injection rate and the mole fractions of each component in injection gas. The corresponding computer program makes a progress in automatic optimal design of development of condensate reservoirs.

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PRESSURE-VELOCITY FINITE-DIFFERENCE METHOD IN ACOUSTIC LOGGING Dong Hefeng, Wang Kexie, Li Rong hua 1998, 15(1): 77-82.  Abstract ( )   PDF (250KB) ( )   A pressure-velocity finite-difference (PV-FD) method is presented for simulating the transient acoustic field of the acoustic logging problem with horizontal multilayer elastic solid or two-phase media formation. In this method, the pressure and velocity are, respectively, chosen as the variables to describe the motion of media inside and outside the borehole. The boundary conditions for pressure and velocity at borehole wall are given in cylindrical coordinate, and they are treated by conservation integral method. The PV-FD method has some advantages, especially for solving the acoustic logging problem. The treatment of singular point source is more simpler. Inner-boundary equations at the borehole wall established with pressure and velocity is of advantage for calculating stability. The absorbing effect of the artificial boundaries can be got improvement. By comparing with the results of Fourier transform under the circumstance of the homogeneous formation outside the borehole, and simulating the acoustic pressure field with the horizontal-layered elastic solid formation, the effectiveness and accuracy of this method has been examined.

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THEORETICAL STUDIES OF BACKLIGHTER FOR INDIRECT-DRIVE RAYLEIGH-TAYLOR EXPERIMENTS Wang Guangyu, Gu Peijun, Sheng Jiatian 1998, 15(1): 83-88.  Abstract ( )   PDF (246KB) ( )   For Rayleigh-Taylor instability experiments diagnosed by backlight X-ray image on a moderate power laser facility, several kinds of backlighter materials and thier X-ray spectra have been studied theoretically. The simulated results show that it is possible to produce about 2 kev X-ray backlight using a several hundred Jaules 2ω0 laser.

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Discrete Hankel Transformation Yu Li, Huang Meichun, Chen Wenzhong, Zhu Zhizhong, Chen Mouzhi 1998, 15(1): 89-94.  Abstract ( )   PDF (225KB) ( )   Discrete Hankel transformation is defined where discrete Parserval theorem and transformation matrix are derived. It is show ed that the weight factor and S-factor play important roles in the analysis and calculation.

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A NUMERICAL STUDY FOR N-S EQUATION IN ARBITRARY CURVILINEAR COORDINATES WITH NONSTAGGERED GRIDS Zhu Songlin, Wang Xianfu, Lu Ruisong 1998, 15(1): 95-100.  Abstract ( )   PDF (233KB) ( )   This paper presents numerical solution for governing equation of flows in curvilinear coordinate system with nonstaggered grids.In order to cure the zig zag variation of pressure,the cell-face velocity interpolation method is developed for solving the pressure-velocity-coupling problem,SIMPLER algorithm is used.With the overall methods present here,the flow in a 90° square duct is calculated.The results agree well with the experiment data.

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AGE Method of First-Order Hyperbolic Equation Liu Bai Liang 1998, 15(1): 101-106.  Abstract ( )   PDF (206KB) ( )   An explicit finite difference method for the solution of first-order hyperbolic equation is presented by combining the group explicit method with the numerical boundary condition.The stability of the method is proved.Some numerical results of two model problems are also given.

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SPECTRAL FINITE ELEMENT METHOD OF TRANSPORT EQUATION FOR NEUTRON LOGGING PROBLEM Mei Liquan, Huang Aixiang 1998, 15(1): 107-113.  Abstract ( )   PDF (259KB) ( )   The application of spetral finite elment method to well-logging problem is discussed.Using spherical harmonic function expansion and finite element method,Boltzmann transport equation is solved numerically,the convergence of the method is approved.A 3-D software is developed to simulate the neutron logging,and the results are satisfied.

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BLOCK ADI METHOD FOR THE TWO-DIMENSIONAL CONVECTION-DIFFUSION EQUATION Zhang Baolin, Lu Jinfu, Kuang Jianping 1998, 15(1): 114-120.  Abstract ( )   PDF (226KB) ( )   The Block ADI(Alternating Direction Implicit) method for solving the two-dimensional convection diffusion equation is developed in this paper.The Block ADI method is unconditionally stable and has the localization property of both computation and communication,so the method can be used on the massively parallel processing system with distributed memory processors.The numerical example is given on a parallel system of networks of work stations.

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A COMPARISON OF EXPLICIT AND IMPLICIT NUMERICAL METHODS FOR UNSTEADY TRANSONIC FLOW Yang Guowei, Li Fengwei, Zhuang Lixiang 1998, 15(1): 121-127.  Abstract ( )   PDF (280KB) ( )   The explicit and implicit methods are employed in the numerical simulation of unsteady transonic NACA10012 airfoil flow,and comparison analyses have been made in the respects of computational results,efficiency,and sensitivity to grid quality.