Archive

25 December 1993, Volume 10 Issue 4 Previous Issue    Next Issue

---

For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Select

A NEW APPROACH TO FADDEEV INTEGRAL EQUATIONS WITH CONTINUOUS SPECTRUM Zhang Tianyuan, Mo Junyong 1993, 10(4): 385-395.  Abstract ( )   PDF (642KB) ( )   Faddeev equations with local potentials in the momentum space are two-variable integral equations whose kernels have singularities in the case of break-up proceses and three-body scattering. In the frame of singular integral equation theory a numerical technique for solving the two-variable equations is presented. The practice shows that numerical solutions converge. Differential Cross-sections for complete kinematics are obtained. It is clear that the aqreement between the theoretical results and the experimental ones is very well.

Select

THE CALCULATION FOR THE RUNAWAY ELECTRON DISTRIBUTION FUNCTION AND WAVE ENERGY DENSITY IN TOKAMAK Jian Guangde, Ding Houchang 1993, 10(4): 396-404.  Abstract ( )   PDF (507KB) ( )   The quasilinear differential equations are solved by finite difference method with non-equidistant scheme. The evolution of the runaway electron distribution function and wave energy density are obtained in interval of electron parallel velocity. These solutions are shown to be more complete than that given in [1] and [2] for both the stationary case and the evolution of functions in one-dimension. The results are useful for further study of runaways.

Select

NUMERICAL COMPUTATION OF ENERGY TRANSPORT IN TOKAMAK PLASMA BY OHMIC HEATING He Qibing, Ding Ning, Long Yongxing, Huang Lin 1993, 10(4): 405-412.  Abstract ( )   PDF (412KB) ( )   A set of nonlinear second order parabolic partial differential equations with initial-boundary values is approxinated by Crank-Nicholson difference method, and successfully solved by means of Loop-Iteration method. The computation of energy transport in tokamak plasma by ohmic heating provides numerical results in agreement with the theoretial analysis.

Select

HIGH ORDER TRIDIAGONAL OCI DIFFERENCE SCHEME FOR ORDINARY DIFFERENTIAL EQUATIONS WITH BOUNDARY VALUES Peng Dianyun 1993, 10(4): 413-421.  Abstract ( )   PDF (520KB) ( )   This paper presents basic idea to construct high order difference schemes for linear two order ordinary differential equations with boundary values. A six order tridiagonal OCI difference scheme is deduced and the singularity at ends of interval are treated by means of limited values. A six order tridiagonal OCI difference scheme on non-uniform mesh is adopted for layer problems. A large number of numerical experimental results show that this high order tridiagonal OCI difference scheme can solve singular problems, inherent instability problems, dichotomous instability problems, singular perturbation problems and oscillating problems very well.

Select

NUMERICAL STUDY OF THE AXISYMMETRIC FLOW OVER A MISSILE AFTERBODY Zhou Weijiang, Ma Handong 1993, 10(4): 422-428.  Abstract ( )   PDF (761KB) ( )   The interaction between supersonic external flow and an exhaust jet forms a complex flowfield region near the missile afterbody. In this paper, the research about this interaction flows was completed with finite-difference method to solve N-S equations. The flowfield structures observed in experiment and it's relation with jet pressure ratio pj/p∞ were obtained. For freestream, M∞=1.94, Re∞=2.2×105, for jet flow, Mj=3.0, three pj/p∞(1.03, 0.527 and 0.15) were selected. The numerical algorithm used is a modified Beam-Warming scheme. The nozzle base pressure coeficient and shock reflection length were compared with experimental data, good agreements were reached.

Select

THE GENERALIZATION OF MAC TECHNIQUE TO NON-NEWTONIAN FLUID FLOW Tang Yinong, Chen YaoSong, Chen Wenfang 1993, 10(4): 429-443.  Abstract ( )   PDF (695KB) ( )   The Marker-and-Cell technique is modified and generalized to the flow problems of non-Newtonian fluid, especially of viscoelastic fluid. The solution can be obtained for reasonably high elastic Deborah number. Discussions are also on the bubble formation and growth at the orifice submerged under the Maxwell liquid in finite extent, which is a typical problem incorporating varieties of complexity, including the non-sphericity of the bubble, the viscoelasticity of the liquid and the complex flow field.

Select

THE ESTIMATION TECHNIQUE ABOUT THE INTERFACE OF POTENTIAL SYSTEMS Pan Xiaosu 1993, 10(4): 444-450.  Abstract ( )   PDF (407KB) ( )   An estimation technique about the interface of potential systems from the boundary data, which can be transformed into a constrained minimization problem of functionals, is discussed. The well-known augmented Lagrangian algorithm applies to solutions in the numerical calculations with finite element discretization technique.

Select

CALCULATIONS OF OPTICAL SCATTERING CROSS SECTION FOR COMPOSION Al2O3/MgO/C MICROSCOPIC PARTICLES Shen Chenhua, Lin Guifen 1993, 10(4): 451-455.  Abstract ( )   PDF (280KB) ( )   An optical scattering cross section calculation formula is derived for homogeneous spherical microscopic particles of three components. Scattering cross sections for spherical composite microscopic particles Al2O3/MgO/C are computed. Curves for scattering cross section as a function of core particle radius and MgO Carbon layer thickness are given with discussions on results.

Select

APP LICATION OF THE BOUNDARY ELEMENT METHOD TO THREE-DIMENSIONAL ANALYSIS FOR ACOUSTIC CHARACTERISTICS OF EXPANSION CHAMBER WITH MEAN FLOW Ji Zhenlin, Ma Qiang, Zhang Zhihua 1993, 10(4): 456-466.  Abstract ( )   PDF (623KB) ( )   The boundary element method is applied to analyse three-dimensional acoustic characteristics of ducts and expansion chambers with mean flow, The boundary integral equation and fundamental solution of wave propagation in the presence of mean flow have been obtaind. The nine nodes quadratic isoparametric elements areused to discretize boundary surface. The polar coordinate transformation method and indirect method are jointly used to treat singular integration problem, the different partical vibrating velocities are supposed at points of corner, the four-pole parameters of a stright duct and transmission loss of an expansion chamber with and without mean flow have been calculated and compared with results obtained by means of one-dimentional theory and other methods.

Select

APPLICATION OF THE BOUNDARY ELEMENT METHOD TO CALCULATING ACOUSTIC CHARACTERISTICS OF DUCTS AND MUFFLERS WITH A LINEAR TEMPERATURE GRADIENT Ji Zhenlin, Zhang Zhihua, and Ma Qiang 1993, 10(4): 467-470.  Abstract ( )   PDF (247KB) ( )   Bu using the perturbation method, the sound wave propagation equation in the medium with a linear temperature gradient is simplified into Helmholtz equation, which can be computed numerically with the boundary element method. The four-pole parameters of muffler can be obtained using BEM, therefore the acoustic characteristics such as transmission loss can be predicted. The four-pole parameters of a straight duct and transmission loss of an expansion chamber have been calculated and compared with the results obtained by means of one-dimensional theory.

Select

3-D SIMULATION CODE FOR FREE ELECTRON LASER Shi Yijin, Weng Zili 1993, 10(4): 471-478.  Abstract ( )   PDF (481KB) ( )   In the similar frame of the code FELEX without degradiug calculation precision and by applying direct inversion of matrix, transformation of variables and other methods, a goal to redue 1-2 orders of computer CPU time is reached, the code running in PC 386/25 is established.

Select

A GROUP EXPLICIT METHOD FOR BURGERS EQUATION Wang Ziding, Lu Jinfu, Xiao Shijiang 1993, 10(4): 479-487.  Abstract ( )   PDF (466KB) ( )   A new group explicit scheme for solving Burgers equation is constructed by the conservative Samarskii scheme. The linear stability of this method is discussed. Some numerical examples are given which illustrated that the present method is more suitable than Evans's method for solving Burgers equation with a large Reynolds number.

Select

PRACTICAL SCALED FORMULA FOR HYDROGENIC IONS BY ELECTRON-IMPACT EXCITATION CROSS SECTIONS Jia Baolin, Long Yanqiu 1993, 10(4): 488-501.  Abstract ( )   PDF (825KB) ( )   A set of practical parametes on hydrogenic ions is given for electron-impact excitation cross sections and rate coefficients with transitions nl→n'l',n1,2,...,7, n'=2, 3,..., 8. Application ranges are 3≤ Z ≤74;x≥2 for n'≤5;x≥20 for n'≥5. The errors are generally about 30%.

Select

A TWO-STEP IMPLICIT SCHEME FOR THE NUMERICAL SOLUTION OF NAVIER-STOKES EQUATIONS Ye Jian, Shan Fangfang 1993, 10(4): 502-506.  Abstract ( )   PDF (284KB) ( )   The purpose of this paper is to introduce a new implicit fractional step altorighm of two processes for the calculation of the transport equations of fluid flows i.e., the convection-diffusion process and propagation process.It is found that the second step of the propagation process in the present method resembles the velocity-pressure correction procedure in the SIMPLE-like methods, and the SIMPLEC algorithm is a special case of the proposed method. Two numerical examples of laminar flows show that the rate of convergence can be significantly improved by the change of the optimal coefficient α.

Select

A MODIFIED LAMBDA SCHEME FOR AXISYMMETRIC FLOW Peng Shiliu, Yu Shaozhi, Gao Zhi 1993, 10(4): 507-512.  Abstract ( )   PDF (310KB) ( )   In this paper, a modified scheme is developed, which can be used for calculation of axisymmetric fluid flow. A set of Euler equations of generalized Rieman variable is derived and solved by two step upwind scheme. The convergence is good because of the consideration of dependent domain of information. Because of using only one point except the unknown one, this scheme is simple and coding is easy. As a example, this scheme has been used for the inviscid subsonic-supersonic flow around blunt bodies at supersonic speeds, the merits of this scheme is demonstrated by these numerical experiments.

Select

HARTREE-FOCK BASIS PROGRAM WITH ρ=αr+βlnr RADIAL MESH Xi Jinhua, Wu Lijin, Li Baiwen 1993, 10(4): 513-516.  Abstract ( )   PDF (260KB) ( )   Based on the multi-configuration Hartree-Fock program code designed by Fischer, a program code is presented for treating the bound states as well as the continuum states, with transforming the radial mesh from ρ=lnZr to ρ=αr+βlnr. As an illustration of the completeness of the basis sets obtained from this program, the results of Thomas-Reiche-Kuhn sums under the Coulomb potential, are given as well.

Select

MONTE-CARLO SIMULATION ON THE ACCEPTANCE OF AN AIR SHOWER ARRAY Zhang Xusheng 1993, 10(4): 517-522.  Abstract ( )   PDF (358KB) ( )   By assuming that (1)the lateral structure of an air shower follows the NKG function and (2)the Poisson distribution can be used to select real detective particle density for each particle density detector, in which the mean value is determined by NKG function (i.e.(1)),and making use of Monte-Carlo method, the effective area (i.e.acceptance) for the air shower array of Mt. Liang Wang Cosmic ray observation station is simulated numerically. The calculated response function from simulation values of effective area agrees well with the observed results of the EAS array experiment, and it is good to use simulation values of effective area to analyse experimental data of the EAS array. This fact confirms that the simple method of calculating effective area is proper and appicable.

Select

IMPLANTATION AND DEVELOPMENT OF FRITIOF CODE Wang Zhongqi 1993, 10(4): 523-524.  Abstract ( )   PDF (192KB) ( )   Fritiof code system is a general-purpose international code in particle physics. It simulates the hadron-hadron, hadron-nuclei and nuclei-nuclei collision process with Monte Carlo method. A brief introduction is given to its theortical model, functions and characters, the implantation, development and applications of the code.