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25 May 2005, Volume 22 Issue 3 Previous Issue    Next Issue

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A General Form of the Dispersion-controlled Dissipative Scheme and Its Application in Detonation Problems CHANG Li-na, ZHANG De-liang, HU Zong-min, JIANG Zong-lin 2005, 22(3): 189-196.  Abstract ( )   PDF (594KB) ( )   A general form of the dispersion-controlled dissipative (DCD) scheme is proposed.An unstructured DCD is constructed and its reliability is demonstrated with numerical simulations.Comparisons of the unstructured results with the second order structured results reveal that the previous resolution is well retained.In order to simulate detonation problems,unstructured DCD is combined with detailed chemical reaction kinetics.The algorithm is used to simulate detonation propagating along a straight duct with or without a wedge.Comparison of the numerical simulations and experiments shows that the algorithm works well in capturing detonation waves.Neither numerical oscillation nor artificial viscosity occurs in practical calculations.

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A Numerical Study on Fully Developed Turbulent Flows: A Wavelet Analysis LIU Yu-lu, JIANG Jian-bo, QIU Xiang, LU Zhi-ming 2005, 22(3): 197-205.  Abstract ( )   PDF (445KB) ( )   A numerical study on fully developed turbulent flows is conducted by solving the integral Navier-Stokes (N-S) equation with Gaussian wavelet transformation.Gaussian wavelet is used to obtain the N-S equation with flexion as a fundamental quantity in an infinite domain.The (N-S) equation with flexion as a fundamental quantity in a finite domain is shown.The integral N-S equation is regarded as a special diffusion equation and the pressure term,convective term are regarded as source terms.The general solution of the integral equation is obtained with the characteristic method.The results are used to the analysis of channel turbulent flows in asymmetric and symmetric channels.A comparison of the calculated mean statistical quantity with the experimental result is made.

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The Construction of Jet Symplectic Difference Scheme for Hamiltonian Systems via Generating Functions YU Hua-ping, WANG Shuang-hu 2005, 22(3): 206-216.  Abstract ( )   PDF (476KB) ( )   A method preserving structures of the Hamiltonian systems is considered. On the basis of the jet symplectic difference scheme for canonical Hamiltonians the jet symplectic difference scheme for Hamiltonian systems in general symplectic structure with variable coefficientsic is defined. According to the general approach of the generating function method for the symplectic difference schemes a relation between the general symplectic structure and the generating functions is found. The jet symplectic difference schemes for classical Hamiltonian systems are constructed in terms of Hamilton-Jacobi equation.

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A Study on the Ferroelastic Phase Transition in Cubic Systems with the Slowness-Curved-Surface ZHOU Guo-xiang, WANG Ai-kun, HE Wen-chen, LI Guo-chang 2005, 22(3): 217-220.  Abstract ( )   PDF (201KB) ( )   The relationship between the slowness-curved-surface and the softening of the acoustic mode is discussed.The acoustic mode softening of cubic systems corresponds to the maximum slowness.The eigenvector in the soft mode corresponds to the polarization of acoustic mode.By solving the Christoffel equation,the maximum slowness and the polarization of the acoustic mode are obtained.The symmetry change of proper ferroelastic phase transition of cubic systems is determined by the solution of the Christoffel equation and the Curie principle.

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Asymmetrical Vortex Breakdown of Delta Wings at High Incidence XIAO Zhi-xiang, CHEN Hai-xin, FU Song, LI Feng-wei 2005, 22(3): 221-226.  Abstract ( )   PDF (448KB) ( )   A fully implicit Lower-Upper-Symmetric-Gauss-Seidel (LU-SGS) with pseudo time sub-iteration and the modified Jameson's central scheme are applied to solve thin layer Navier-Stokes(N-S) equations with laminar hypothesis and Baldwin-Lomax(B-L) model for the vortical flows around delta wings at high angles of attack (AOA).To validate the codes,a 65 degree swept delta wing is computed in transonic cases,where M∞=0.85,α=10°,20° and Re=5×106.Then asymmetrical vortex breakdown flows with M∞=0.3,and Re=1.3×106,at high AOA around an 80° swept delta wing are presented and discussed.The computational results are compared with experimental data available and good agreement is achieved.

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A Study on the Complex Terrain Dispersion Model (CTDM) FAN Li-ya, ZHANG Mao-shuan, SANG Jian-guo, LIU Shu-hua 2005, 22(3): 227-232.  Abstract ( )   PDF (378KB) ( )   The Complex Terrain Dispersion Model (CTDM) developed by the American Environmental Protection Agency (EPA) is applied to Qinshan Nuclear Power Plant (QNPP) in China.The ground plume centerline concentrations of atmospheric pollutant in PhaseⅠ,Ⅱ and Ⅲ are calculated.The results are compared with that of wind tunnel experiments and a few field data.Two revising methods for LIFT are put forward.Model reliability test shows that the revising methods are more accurate.The ratios of calculated result to the measurement in the domain of 1/3.5~3.5 are:54.4% in CTDM,72.9% in revision A, 58.6% in revision B.In addition,the model sensitivity is analyzed.

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A Simplified Time-domain Finite-difference Beam Propagation Method in the Analysis of Fiber Bragg Grating DAI Jin-cao, WANG Yun-ming, ZHANG Ming-de, SUN Xiao-han 2005, 22(3): 233-239.  Abstract ( )   PDF (468KB) ( )   Under a compulsive boundary condition,a simplified time-domain finite-difference beam propagation method (TD-FD-BPM) suitable for the analysis of fiber Bragg grating (FBG) is presented.In the alternating-direction implicit method (ADIM) and the generalized Douglas (GD) scheme, the time-domain beam propagation equation is discretized with a truncation error two orders lower than that of conventional finite-difference scheme.The compulsive boundary condition simplifies the boundary model,which is important in the numerical analysis of optical waveguides with open boundary conditions.We focused on the position of excitation,the shape of the pulse and its distribution in the radial direction,and the use of the one-way continuous-wave (CW) scheme.Using a modified sinusoidal pulse,a satisfactory reflective spectrum is obtained in a short symmetrical FBG through discrete Fourier transform.

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A Fast SA Algorithm for the Design of DOE for Uniform Illumination LIU Hong-liang, ZHAO Yi-qiong, LI Yong-ping, FU Shao-jun, ZHANG Wei, ZHANG Xiao-bo, SHU Fang-jie 2005, 22(3): 240-244.  Abstract ( )   PDF (260KB) ( )   A fast simulation annealing (SA) algorithm for the design of diffractive optical elements (DOE) for uniform illumination is presented.The Tsallis statistic and corresponding utility function are introduced into a hybrid algorithm in which the self-iterative and SA algorithms are combined to enhance the efficiency.Compared with traditional SA algorithm,simulated results show that it saves 99% of time to converge the incident energy into a desired region with the same mean square error (MSE).

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Monte Carlo Simulations of Electron Transport in Silicon Carbide WANG Ping, YANG Yin-tang, QU Han-zhang, YANG Yan, LI Yue-jin, JIA Hu-jun 2005, 22(3): 245-250.  Abstract ( )   PDF (362KB) ( )   The electron transport properties in 2H-,4H-,and 6H-Silicon Carbide are investigated numerically with an ensemble Monte Carlo technique.The acoustic phonon deformation potential scattering,polar optical phonon scattering,intervalley phonon deformation scattering,ionized impurity scattering and neutral impurity scattering are considered.The electron mobilities of 2H-,4H-,and 6H-SiC as a function of temperature at low electric field are obtained.The influence of the neutral impurity scattering on the transport property of 4H-SiC is discussed in detail.Finally,the static and transient variation of electron drift velocity in high electric fields are studied.The peak transient velocity in an electricfield of 1.0×106 V·cm-1 is 3.3×107cm·s~(-1) for 4H-Sic and 3.0×107 cm·s-1 for 6H-Sic when the electric field is applied perpendicular to the c axis.The simulated results are in good agreement with recent experiments in a wide range of temperature and electric field.

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A New Model for the Steam Properties in Steam Injection Wells NI Xue-feng, CHENG Lin-song, LI Chun-lan, AN Jiu-quan 2005, 22(3): 251-255.  Abstract ( )   PDF (282KB) ( )   The steam pressure equation is deduced with the momentum theorem while the steam quality equation is deduced with energy balance.The model is solved with nodal analysis and numerical calculation.The property parameters of the steam mixture are calculated with the traditional Beggs-Brill method.The calculation results are compared with the detection on 10 steam injection wells (Qi 40 and Du 80)in Liaohe Oil Field,which indicates that this model works well in calculating the steam properties of steam injection wells.

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Electronic Structure and Nonlinear Properties of Charged Fullerenes C60 LIU Hong 2005, 22(3): 256-260.  Abstract ( )   PDF (269KB) ( )   The geometry and electronic structure of charged molecules C60 are studied in the Su-Schrieffer-Heeger (SSH) model.The influence of the charge taken by C60 molecules on their structure and the electronic structures are analyzed.The third-order polarizabilites of C60 molecules with different charge are calculated.

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Basic Functions in the Method of Moment for 2D Electromagnetic Scatterings ZHU Feng, ZHAO Liu 2005, 22(3): 261-263.  Abstract ( )   PDF (180KB) ( )   The basic functions in the method of moment (MoM) for 2D electromagnetic (EM) scattering problems that is symmetric about X-axis and Y-axis are obtained with the represention theory of finite group.We construct the group and get its regular representations.The tentative functions according to the four center symmetric positions are shown.While the regular representation is transformed into an irreducible one,orthonormal basic functions composed of the tentative functions are obtained.

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Performance Analysis and Application of 2-D Plasma Parallel Particle-in-cell Simulations LU Quan-ming, DOU Xian-kang, WANG Shui, WANG Shu 2005, 22(3): 264-270.  Abstract ( )   PDF (522KB) ( )   The implementation of a 2D parallel particle-in-cell (PIC) simulation with domain partition is presented.Its performance is tested on a PC cluster of 16 Pentium Ⅲ 1.6 CPUs. It shows that the parallel efficiency decreases with the increasing of computation nodes while keeping the calculation size; and the parallel efficiency increases with the size of physical problem while keeping the number of computational nodes. It means that parallel computing is suitable for large physical problems. As an example, a calculation on plasma beam instability is performed with this parallel PIC code. The results show that in the linear growth stage, the excited Alfven waves propagate in the direction of ambient magnetic field, and they satisfy a resonant condition ω-kVb=-Ωi, where ω and k are frequency and wave number of the excited Alfven waves, respectively, Vb the beam velocity and Ωi the ion cyclotron frequency.

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Double-Gauss Quadrature for Discrete Ordinate Transport Equations with Cylindrical Geometry ZHU Rui-dong, LI Mao-sheng 2005, 22(3): 271-276.  Abstract ( )   PDF (314KB) ( )   An accurate angular quadrature is developed with cylindrical symmetry in transport equations. The most appropriate quadrature for polar angles is the Double-Gauss and for azimuthal angles is the Chebyshev-Gauss in cylindrical geometry. Numerical comparisons of quadratures on two standard problems are shown. They suggest that the new quadrature proves competitive for transport problems both in reducing ray effects and in improving accuracy.

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An Improvement on the Discrete Ordinate Method in Simulating Radiative Heat-transfer YANG Zhan-chun, WU Wen-fei, LI Yi-ke 2005, 22(3): 277-282.  Abstract ( )   PDF (319KB) ( )   An improvement on the Discrete Ordinate Method (DOM)-‘divide and rule’is shown. The tiny dominated body is plotted into districts according to the projection relation between the interfaces in the radiative heat-transfering direction. The radiative intensity of the subsidiary dominated bodies is solved after an integral to the radiative heat-transfering equation in the radiative heat-transfering direction. In the new DOM, the average volume is regarded as the final radiative intensity of the nodes. Numerical simulation is performed on the process of radiative heat-transfer in a three-dimension rectangular furnace. Compared with the traditional DOM and the district method, numerical results indicate that the new DOM solves the fake scattering preferably, and ameliorates the precision of the calculation as well.