Archive

25 September 1987, Volume 4 Issue 3 Previous Issue    Next Issue

---

For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Select

THE NUMERICAL SIMULATION OF NEAR WAKE FLOW Ma Yan-wen, Fu De-xun 1987, 4(3): 237-244.  Abstract ( )   PDF (427KB) ( )   Near wake flow is simulated by using numerical method for solving the Navier-Stokes Equations.In order to get fine solutions near the corner coordinate transformation is made in both x and y directions.The differetial equations are approximared with factored implicit scheme developed in(1). The scheme is implicit, and large time step can be used. But the difference solutions can be expressed explicitly. In process of solution there are no numerical inversions of matrices and no matrix operations.The scheme has advantages of both implicit and explicit schemes.Flows with different Mach number M and Peynolds number Pe are computed.

Select

A NEW COMPUTATIONAL METHOD FOR PLANE STEADY SUPERSONIC FLOW WITH SHOCK WAVE Du Xun 1987, 4(3): 245-252.  Abstract ( )   PDF (386KB) ( )   A new computational method for plane steady supersonic flow with shock wave is developed. The differential equations and boundary conditions in new lagrangdan variables are formulated. We calculated a specific case that the equation of solid surface is a parabola y=(1)/(2)x2.In this example, theshape of the shock wave is calculated. Before the formation of the shock wave,the flow has an exact solution.Our computational results coin-side well with the exact solution.

Select

A LOW-REYNOLDS-NUMBER PROBLEM OF AN ARBITRARY AXISYMMETRIC BODY ROTATED IN AN LNFINITE LONG TUBE Jiang Jun, Wu Wang-yi 1987, 4(3): 253-262.  Abstract ( )   PDF (577KB) ( )   In this paper, an axisymmetric Stokes flow induced by the rotation of an arbitrary axisymmric boby in an infinite long tube is studied. An infinite series of Sampson rotlets is taken as the fundamental singularities. For the strength of the continuous distribntion ofsing-ularities along the axis of symmetry both a discrete distribution and a piecewise parabolic distrobution are used. The above analgtical treatment greatly reduce the amount of numerical computation of the stokes flow, while giving very accurate numerical results. Analysis of the numerical results indicates that the parabolic distribution method has advantage over the discrete one in every aspect. Besides, the creeping motion of finite clusters of rotating spheres in the tube is also treated eggiciently and the torque coefficients of each sphere are given.

Select

CALCULATION OF NEUTRON COLLISION PROBABILITIES ON THE MIXED REGION IN TWO-DIMENSION Ma yi-chen, Gao Wei Fan, Bi-jian, Tang Fu-chu, Yao En-de 1987, 4(3): 263-274.  Abstract ( )   PDF (657KB) ( )   In this paper the formulae of the collision probobilities for the isotro-pic two-dimensional neutron transport problem on the mixed region consisting of rectangular or triangle cells are given. Based on these formulae the code has been developed and applied to tow-dimensional mixed cells calculations. The calculated results show good agreement with those of Montecalo method and conservation principles.

Select

A CODE FOR SOLVING THE 3-D STEP FLOW BY USING FULL N-S EQUATIONS Liu Chao-qun, Tang Hao 1987, 4(3): 275-283.  Abstract ( )   PDF (501KB) ( )   Using SIMPLE method,we program a code to solve the 3-D incompressible N-S equations. We compute a 3-D step flow as an example problem, compare it with the 2-D step flow results, and analyse the effects of side walls.

Select

ANALYTICAL CALCULATION OF THE RADIAL INTEGRALS Cai Chong-hai, Wang Si-wen 1987, 4(3): 284-298.  Abstract ( )   PDF (695KB) ( )   In this work we describe a method from which one can conveniently derive the analytical expression of the radial integralsn1l1FLn2l2(q)≡∫0∞ (Rn1l1·(αr)jL(Kr)Rn2l2(αr)r2dr(q≡(K)/(α)). We also give the analytical expressions of for n1l1FLn2l2 L=0,1,2, and a general form of the radial integrals for all L,n1,l1,n2,l2 expressed by multi-sum.

Select

NUMEROV ITERATION METHOD FOR SECOND ORDER INTEGRAL-DIFFERENTIAL EQUATION Zeng Fan-an, Zhang Jia-ju, Zhao Xuan 1987, 4(3): 299-306.  Abstract ( )   PDF (410KB) ( )   In this paper, Numerov iterative method for second order integral-diffe-rential equation arid system of-equations are constructed. Numerical examples show that this method is better than direct method (Gauss elimination method) in CPU time and memery require. Therefore,this method is an efficient method for solution of integral-differential-equation in nuclear physics.

Select

ON THE METHOD OF ATOMIC RADIUS DETERMINATION IN SCF-Xα-SW CALCULATION Tang Jing-chang, Chen Yi-bing 1987, 4(3): 307-316.  Abstract ( )   PDF (661KB) ( )   The electronic structures of impurity in silicon have been studied by SCF-Xα-SW method, it is shown that the electronic structure is depending strongly on the atomic radius in the cluster. We have proposed two rules to determine the atomic radius:1) Adjusting the atomic radius of master element according to the band properties of crystal;2) Determining the radius of impurities in terms of minimizing the total energy of cluster.The calculations of electronic structure of Si:Pd and Si:Pd systemsshave demonstrated that these rules are efficient.

Select

STELLAR CORE COLLAPSE AND EQUATION OF STATE (Ⅰ)——IMPUTTING PHYSICS FACTOR OF COLLAPSE CALCULATION Wang Yi-ren, Huang Wei-zhang, Zhang Suo-chun, Zhang Tian-shu 1987, 4(3): 317-328.  Abstract ( )   PDF (721KB) ( )   In this paper, the properties of system consisting of various nuclear species and free nucleons are described by a nuclear statistical equilibrium system consisting of a typical heavy nucleus, a particles, free neutrons and protons.starting from a semiempirical expression for the mass of the heavy nucleus and the entropy (energy) of their excited states, an equation of state is developed by a restricted minimization of the total free energy of a fixed volume of matter at given temperature and electron fraction.his scheme gave good agreement with the equation of El Eid & Hillebrandt at density 109-1012g cm-3 and with lamb et al (ILPR's equation of state at density 1012-1014g cm-3,ye=3,σ/k=1.5k.The imput physics such as the rate of electron capture on matter has been treated also more carefully.

Select

STELLAR CORE COLLAPSE AND EQUATION OF STATE (Ⅱ)——COMPUTER SIMULATION OF STELLAR COLLAPSE Wang Yi-ren, Huang Wei-zhang, Zhang Suo-chun, Zhang Tian-shu 1987, 4(3): 329-338.  Abstract ( )   PDF (624KB) ( )   We take 15 M☉ model of Weaver et al. as initial model,the collapse process of stellar core between the onset of collapse and core bounce has been calculated by using the eouation of state of us (EOSⅡ).With the simplified nuclear statistical equilibrium system mentioned above, the treatment of the thermal effects of neutronization, nuclear disintegration, nuclear combination and nuclear excitation has been attemped.The results of us are essential agreed with Van Riper's results.calculated by using the ILPR's equation of state for the same initial model.As the center density of core reaches 1014gcm-3, the maximum velocity of fall and the Ms (mass at sonic point)in model D is greater than that of the typical model of Van Riper by 2.7% and 7% respectively. In model D the neutrino trapping density is less than that of the typical model of Van Riper by 3% (at mass layer 0.15M☉) but the lepton fraction in model D is greater than that of typical model of Van Riper by 8%(at 0.15M☉) and by 10% (at 0.5M☉).

Select

CHMCK——A MONTE CARLO CRITICALITY PROGRAM FOR COMPLICATED GEOMETRY SYSTEMS Dong Xiu-fang 1987, 4(3): 339-347.  Abstract ( )   PDF (627KB) ( )   CHMCK is a Monte Carlo criticality program used for complex geometrical nuclear systems.The nuclear system considered might be composed of units, each of which could be divided into several regions with different materials.The surface of the regions consist of one of conies rotating sur-faces(planes,spheres,cylinders,cones,paraboloids,ellipsoids or hyperbololds) or their combination.The axis of the rotating surface may be oritented in any manner and the surfaces may intersect with each other in arbitrary fashion.Thus CHMCK is applicable to the majority of criticality calculation.Comparing with the famous program KENO(2,8),CHMCK has the merits of convenience and intuition for inputing and operating,due to the adopting of maximum cross section method(6) in neutron transport which simplifies the program and saves the CPU time for complex geometrical.

Select

NUMERICAL ANALYSIS OF THE IMPACT MADE BY A PROJECTILE ON A TARGET Wang Ming-rui, Tang Min-jun, Liu Yun-ying 1987, 4(3): 348-356.  Abstract ( )   PDF (526KB) ( )   The problem about a projectile with high veiocity impacting on a target is an important subject in penetration mechanics, It is also an important question in Studying dynamic response of materials.In this paper,the calculations of cylindric steel projectiles impacting on Aluminum targets have been performed using the dual lagrange APHEMP code and the results are compared with the experiments the dynamic picture of the impacting processes is preliminarily Studied.

Select

NUMERICAL STUDY ON GENERAL DISPERSION RELATION OF ANISOTROPIC AND WEAKLY RELATIVISTIC PLASMA Ke Fu-jiu, Chen Yan-ping 1987, 4(3): 357-363.  Abstract ( )   PDF (421KB) ( )   The key problem in heating and instability studies in plasma physics is to obtain dispersive equation and its solution. This paper presents the general dispersive equation and corresponding procedure, when electromagnetic wave nearly poloidally impinges on anisotropic, weakly relativistic Maxwellian plasma with inhomogeneous density in nonuniform magnetic field (such as plasma in TOKAMAK). The double index function Fij, significant in plasma physics, was expanded as single index function F1, and then the values were calculated by means of dispersive function. It was also pointed in the paper that the severe error involved in the calculation of Fij from F11 successively prevents the-technique of recurrence relation from being put into practice.

Select

A UNIFIED STATEMENT OF THE THEOREMS OF THE ANGULAR MOMENTUM Wang Li-zhong 1987, 4(3): 364-370.  Abstract ( )   PDF (342KB) ( )   The question how to choose the centroid in the theorem of the angular momentum has been discussed for thirty years(see references [1]~[4]). This paper gives a unified statement of the theorems of the change in the angular momentum of a system of particles. Especially, We develop the theorem of the angular momentum of a system of particles with respect to the centre of instontaneous zero velocity, in general, it is considered impossible.Using this theorem, we solve an example, the solution of which in this way was considered impossible.

Select

CALCULATION SOFTWARE OF MONTE CARLO SIMULATION OF SPATIAL DISTRIBUTION OF DENSITY OF X-RAY PHOTONS IN SOLID Hu You-hua, He Yan-Cai, Hu Min, Chen Jia-Guang 1987, 4(3): 371-379.  Abstract ( )   PDF (580KB) ( )   Based on the physical model and the calculating method developed by the authors, the calculation software of the spatial distribution of density of x-ray photons in solid is made. The scattering of electron beam with energy in KeV in solid and the excitement of x-ray photons can be simulated by using this program. The quantitative results-of the distributionof density of x-ray photons and the spatial range including various proportion of the photons are also obtained. It is significant for quantitative research of electron microscopy.

Select

A CALCULATION PROGRAM OF DETERMINING THICKNESSES OF THIN FILMS ON SUBSTRATES BY MONTE CARLO SIMULATION He Yan-cai, Huang Yue-hong, Ha Min 1987, 4(3): 380-384.  Abstract ( )   PDF (379KB) ( )   On the basis of author's theories and calculation method[1,2,3],we made a evaluation program of determining thicknesses of thin films on substrates.The software can be conveniently operated,and have already been extensively applied to the calculations for determining thicknesses of avariety of film materials.

Select

INTERNATIONAL CONFERENCE ON COMPUTATIONAL PHYSICS 1987, 4(3): 386-387.  Abstract ( )   PDF (122KB) ( )   It will be held during 1-5 June, 1988 in Beijing that Dexel University and Institute of Applied Physics and Computational Mathematics sponson and organize The International Conference on Computational Physics which is also supported by World Scientific Publications in Singapore, National Center for Supercomputing Applications and Sun Microsystems Inc.in the USA, and in Cooperation:with China Association for Science and Technology.