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25 May 2013, Volume 30 Issue 3 Previous Issue    Next Issue

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JASMIN-based Massive Parallel Computing of Large Scale Groundwater Flow CHENG Tangpei, MO Zeyao, SHAO Jingli 2013, 30(3): 317-325.  Abstract ( )   PDF (1499KB) ( )   To overcome prohibitive cost in computational time and memory requirement in simulating groundwater flow models with detailed spatial discretization and long time period,we present an efficient massive parallel-computing program JOGFLOW for large scale groundwater flow simulation.In the program,groundwater flow process in MODFLOW is re-implemented on JASMIN by designing patch-based algorithms as well as using communication method based on adding ghost cells to each patch.Accuracy and efficiency of JOGFLOW are demonstrated in modeling a field flow located at Yanming Lake in Zhengzhou of Henan province.Parallel scalability is measured by simulating a hypothetic groundwater flow problem with much detailed spatial discretization.Compared to 32 cores,the parallel efficiency reaches 77.2% and 67.5% on 512 and 1 024 processors,respectively.Numerical modeling demonstrates good performance and scalability of JOGFLOW,which enables to support groundwater flow simulation with tens of millions of computational cells through massive parallel computing on hundreds or thousands of CPU cores.

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One-dimensional Shock-tube and Two-dimensional Plate Flows in Boltzmann-Rykov Model Involving Rotational Energy WU Junlin, LI Zhihui, JIANG Xinyu 2013, 30(3): 326-336.  Abstract ( )   PDF (3016KB) ( )   To investigate effect of rotational degree of freedom on gas flows covering various flow regimes,Boltzmann-Rykov model is studied and reduced velocity distribution functions are introduced with quadrature to rotational degree of freedom of molecular velocity distribution function.A single gas-kinetic model equation is translated into simultaneous equations of three reduced velocity distribution functions at discrete velocity ordinate points with discrete velocity ordinate method and numerical integration technique.One-and two-dimensional Boltzmann-Rykov model equations for diatomic gases are computed with finite-difference method of computational fluid dynamics.One-dimensional shock-tube and the two-dimensional flow past erect plate are analyzed in the whole range of Knudsen numbers.Reliability of gas-kinetic unified algorithm(GKUA) is validated in solving one-and two-dimensional flows from free molecular flow to continuum regimes.It is indicated that the gas rarefaction degree and molecular inner degree of freedom affect flow field greatly.And rarefied gas flows with high Knudsen numbers take serious non-equilibrium effect.

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A High Accuracy Unstructured Grid Finite Volume Method for Natural Convection Heat Transfer XIE Yan, OUYANG Jie, ZHOU Wen, REN Chaoqian 2013, 30(3): 337-345.  Abstract ( )   PDF (2372KB) ( )   To make balance between numerical accuracy and computational efficiency,a deferred correction method coupled with high order scheme is proposed for computation of convection flux.Classical benchmark problems,cavity driven flow with high Reynolds numbers,are solved numerically to verify precision and stability of the method.Finally,the method is used to solve Boussinesq fluid of natural convection heat transfer.It shows that the method overcomes numerical divergence effectively in high Rayleigh number problem.It captures accurately isothermal lines and stream lines at different eccentricities in natural convection heat transfer.

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Asymptotic Convergence Analysis and Quantification of Uncertainty in Lagrangian Computations LIU Quan, WANG Ruili, LIN Zhong, LIU Xiqiang 2013, 30(3): 346-352.  Abstract ( )   PDF (326KB) ( )   We introduce asymptotic order of convergence,asymptotic range of convergence and concepts under behavior of Lagrangian computations.We also introduce grid convergence index to Lagrangian computation,and give a program using GCI method.These concepts and methods are used to measure computed values away from numerical asymptotic values.

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Second Order Volume of Fluid Interface Reconstruction Method in Three Dimensions LIANG Xianhong 2013, 30(3): 353-360.  Abstract ( )   PDF (1398KB) ( )   A second order least squares volume of fluid interface reconstruction algorithm with 81 cells in mesh stencil is introduced.The algorithm is compared with Youngs algorithm and a second order least squares volume of fluid interface reconstruction algorithm with 125 cells in mesh stencil.L∞ criteria function in three dimensions is used to measure stationary interface reconstruction errors.Stationary and advecting tests show that the algorithm can track any oriented plane exactly and it is second order accurate.Compared with second order least squares volume of fluid interface reconstruction algorithm with 125 cells in mesh stencil,calculation amount of the algoritm is much smaller.Thus CPU time is saved and computing efficiency is improved.

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Numerical Simulation on Dewetting of Thin Film Containing Insoluble Surfactant YE Xuemin, SHEN Lei, LI Chunxi 2013, 30(3): 361-370.  Abstract ( )   PDF (2902KB) ( )   Dewetting of thin films covered by insoluble surfactant in the presence of wall slippage is considered.PDECOL program is used to simulate evolutions of film thickness and surfactant surface concentration.With perturbation wave variation of film surface,effects of several parameters on dewetting dynamics are examined.It shows that Marangoni stress shortens unstability region at small Marangoni number(M) and the unstability region is extended at large M.Decreasing capillary number leads to shorten unstability region and even restrains dewetting phenomena.The influence of slipping is closely related to M,and it accelerates perturbation growth and shorten dewetted region at small M.Increasing equilibrium film thickness leads surface deformation degree weakened and unstability region extended.Compared with exogenous surfactant,endogenous forms a shorter dewetted region and hence film stability tends improved.

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2D-Simulation Design of an Ignition Hohlraum LI Xin, WU Changshu, ZOU Shiyang, ZHAO Yiqing, LI Jinghong, GU Peijun, ZHENG Wudi, PEI Wenbing 2013, 30(3): 371-378.  Abstract ( )   PDF (3324KB) ( )   We introduce an ignition hohlraum 2D-simulation design method with 2D code.A design sequence,in which X-rays drive tempetature is tuned before P2 asymmetry,is put forward.Details in designing laser power is studied.It indicates that control of P2 asymmetry during trough pulse limits the maximum of filling gas density and expansion of capsule ablator can be restrained by longer drive pulse.An ignition hohlraum 2D-simulation design is given.

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An Operator Splitting Method for Numerical Simulation of Strong Explosion Fireball YAN Kai, LI Ruo, TIAN Zhou, GUO Yonghui, CAO Yuan 2013, 30(3): 379-386.  Abstract ( )   PDF (826KB) ( )   An operator splitting method is developed for numerical simulation of strong explosion fireball.In the approach the system is split into two parts.One part couples radiation and fluid in a hyperbolic subsystem.Another parabolic part evolves radiation diffusion and source-sink terms.We propose a numerical method for stiff source term.It shows that the method maintains efficiency and satisfies the needs of engineering.At last,spatial distributions of parameters in nuclear explosion reflecting fireball evolution are given.The calculation agrees well with empirical formulas.

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Simulation and Analysis of Deuterium-Tritium Thermonuclear Reaction Rate in Velocity Groups LI Meng, LI Baiwen, JIA Hongxiang 2013, 30(3): 387-395.  Abstract ( )   PDF (1424KB) ( )   Thermonuclear reaction rate describing thermonuclear burning efficiency in thermonuclear fusion is studied.As one species atomic nucleus with Maxwell velocity distribution,another species atomic nucleus velocity is divided into several groups.Velocity group thermonuclear reaction rate and averaged thermonuclear reaction rate are deduced,and simulation codes are obtained.Taking deuterium-tritium thermonuclear fusion reaction as an example,velocity group thermonuclear reaction rates and corresponding averaged thermonuclear reaction rates are calculated and analyzed comparing with exact direct integration results.Finally,relation between averaged thermonuclear reaction rate and velocity group number is studied.

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Numerical simulation of Titanium Cathode Sputtering in Nitrogen Microhollow Cathode Discharge GAO Shuxia, ZHANG Su, MENG Xiulan, ZHANG Lianzhu 2013, 30(3): 396-402.  Abstract ( )   PDF (1794KB) ( )   We analyze numerically thermalization process of atoms sputtered from a cathode in N2/Ti micro-hollow cathode discharge plasma by using Monte Carlo method.PIC/MC model is used to simulate nitrogen ion(N2+,N+) bombarding cathode surface.Thermalization process,density distribution and average energy of Ti atoms are calculated.It shows that initial energy sputtered to all directions from 90 percent of Ti metal atoms is less than 30 eV.Its scattering angle is mainly between 30 and 60 degrees.And thermalization maximum of sputtering Ti atoms is appeared at a distance of about 0.04mm from the hollow cathode wall.

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Simulation of Intense Beam Transfer in Double-Cylinder Accelerate Lens LI Chaolong, SHI Haiquan, LÜ Jianqin 2013, 30(3): 403-408.  Abstract ( )   PDF (312KB) ( )   To study intense beam transfer in double-cylinder accelerate lens,a matrix method is applied to transport matrixs in double-cylinder accelerate lens of non-intense and intense beams.A computer code DCALENS was written for pulsed beams transporting in double-cylinder accelerate lens.Optimization techniques are used for given optical conditions.Iteration procedures are adopted to obtain self-consistent solutions in DCALENS.Calculations made by DCALENS and other codes are compared and analyzed.It shows that the greater the beam current,the more apparent beam envelope lateral divergence,as well as the space-charge effect.As beam current is greater than 2A,beam envelope lateral divergence is obvious.

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A Geometric Method for Photoacoustic Wave Profile on Symmetry Axis of an Ellipsoid Particle LI Yong, FANG Hui 2013, 30(3): 409-414.  Abstract ( )   PDF (2262KB) ( )   For photoacoustic wave production of an ellipsoid particle,we derive analytical formula for wave profile on symmetrical axis.It shows that either for a prolate ellipsoid particle or for an oblate ellipsoid particle,wave profile deviates from typical N wave for a sphere particle.Moreover,deviated N wave is found containing characteristic information about shape and size of the particle.It promises a method for investigating shape as well as size of ellipsoid particles by measuring pulsed photoacoustic wave.

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Monte Carlo Simulation of Laser Transmission Through a Smoke Screen WANG Hongxia, LIU Daizhi, SONG Zibiao, YANG Nichen, YANG Chenglai 2013, 30(3): 415-421.  Abstract ( )   PDF (1814KB) ( )   A Monte Carlo model is established to simulate transmission of 1.06 μm laser pulse in graphite smoke screen.Relation between transmittance and graphite particle size,smoke concentration,smoke thickness are analyzed.A convolution method is put forward to calculate waveform of pulse laser through smoke.For δ pulse laser and rectangular pulse laser with different width,time broadening is calculated.It shows that there is an optimal radius(0.16 μm) for graphite smoke particles,at which interference effect is the best for 1.06μm laser pulse.For rectangular pulse laser,the smaller pulse width is,the more remarkable change in pulse shape and temporal broadening are.For microseconds width laser pulse,pulse shape changes and temporal broadening are not obvious.

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Analysis on Pipe Network Resistance Parameter Calibration Approach in District Heat Supply WANG Hai, WANG Haiying, ZHOU Weiguo, ZHOU Haizhu 2013, 30(3): 422-432.  Abstract ( )   PDF (1120KB) ( )   An approach is proposed for calibrating hydraulic network models.The proposed procedure could reconcile results of all scenarios under various operation conditions and utilize prior information selectively.To achieve more accurate roughness with a faster processing,a hybridoptimization technique was developed to exploit advantages of genetic algorithm and active set method.The algorithm was applied to two sample networks,and resulting calibrated model was compared to counterpart in previous literature.The proposed approach was shown stable and estimated parameters were more accurate.

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Solid Solution Structure and Elastic Modulus of Single Atom in Transition Metal Nitrides:First Principle Studies LIU Xuejie, REN Yuan 2013, 30(3): 433-440.  Abstract ( )   PDF (1367KB) ( )   In order to investigate interface structure of composite films,several solid solution structures and elastic properties of a single atom in transition metal nitrides are studied with first principle method based on density functional theory.The calculation shows interesting results:(1) A silicon atom could not form a solid solution in TiN,ZrN,HfN,or TaN crystallites.It is the same for a germanium atom in TiN crystallite.(2) As distance between crystallites becomes large,a silicon atom in TiN,ZrN,HfN and TaN or a germanium atom in TiN may form interstitial or substitution interface structures.(3) A silicon atom in NbN or a boron atom in TiN could form interstitial or substitution interface structures.(4) Interface structures of a silicon atom in VN or a carbon atom in TiN is a substitution structure.Studies of mechanic properties indicate that modulus of elastic,bulk,shear and Young's of lower energy substitution and interstitial solid solution is less than that of transition metal nitrides.

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3D Simulation of Ge Edge-Diffusion Around Clusters in Ge/Pb/Si(111) Growth WU Lili, WU Fengmin 2013, 30(3): 441-446.  Abstract ( )   PDF (1776KB) ( )   A kinetic Monte Carlo simulation is shown to investigate 3-dimensional growth of Ge on Si(111) substrate as monolayer of Pb atoms are pre-deposited as surfactant.We focus on Ge diffusion around edge of clusters.Effects of Ge diffusing around cluster edge,maximum diffusion steps for edge-diffusion and number of nearest neighbors on 3D growth mode are discussed.Coverage dependences of surface roughness are calculated to investigate growth mode.It shows that Ge edge-diffusion around clusters plays an important role on growth mode of 3D film growth.Effects of ES barrier on growth mode on Ge/Pb/Si(111) are explored.

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Effect of Structure and Tacticity on Flexibility and Polarity of Poly (Organosilanes) MA Haizhu, LIN Min, CHEN Yuhong, LIU Qian, JIANG Qian 2013, 30(3): 447-453.  Abstract ( )   PDF (1788KB) ( )   Considering side group structures of poly(organosilanes),unified basic formula are derived with method of configurational-conformational statistics in rotational-isomeric-state model.Characteristic ratios of mean-square radius of gyration for atactic poly(silastyrene)(PSS),polysilapropylene(PSP),poly(methylphenylsiloxane)(PMPS),poly(dimethylsilmethylene)(PDMSM) and poly(dimethylsilylene)(PDMS) chains are obtained.They are 1.45,0.63,0.97,0.69 and 1.99,and ratios of mean-square dipole moment are 2.49,0.99 0.61,0.48 and 0.27,respectively.It is found that effect of temperature,conformational energy,polymerization degree and tacticity of chains on ratios of PSS and PMPS is quite obvious.However,dependences of basic quantity of PSP and PDMSM on side groups,conformational energy and temperature are inappreciable.Dipolar large side groups in analysis flexibility and polarity of poly(organosilanes) is significant.

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Quantum Particle Swarm Optimization Algorithm Based on Bloch Spherical Search LI Panchi, WANG Qichao, SHI Guangyao 2013, 30(3): 454-462.  Abstract ( )   PDF (896KB) ( )   To enhance optimization ability of quantum potential well-based particle swarm optimization algorithm,a quantum particle swarm optimization algorithm based on Bloch spherical search is proposed by analyzing the design of quantum potential well-based particle swarm optimization algorithms.Firstly,particles are expressed with qubits,axis of rotation is established with Pauli matrix,the angle of rotation is obtained with a model of Delta potential well,and search is realized with rotation of qubits in Bloch sphere.Then,to avoid premature convergence,mutation of particles is achieved with Hadamard gates.Such rotation makes current qubit approximates target qubit along with the biggest circle on Bloch sphere,which accelerates optimization process.It shows that the proposed algorithm is superior to the original one in optimization ability.

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Energy Levels of Hydrogenic Impurities in Quantum Ring with Parabolic Potential of Finite Depth ZHENG Wenli, LI Shushen, WANG Xuefeng 2013, 30(3): 463-468.  Abstract ( )   PDF (1220KB) ( )   Energy levels of ground state and low-lying excited states of hydrogenic impurities in InAs quantum rings are investigated with effective mass approximation and perturbation method.It shows that energy levels of electron do not change with electronic radial coordinate.They have characteristics of two-dimensional hydrogen atom energy levels in parabolic potential platform area.Energy levels of electron are sensitively dependent on radius of the quantum ring.There exist a minimum on account of parabolic confinement potential in area of parabolic potential with finite depth.Degenerate energy levels of the first excited state for hydrogenic impurities are not relieved.As n ≥ 2 degenerate energy levels are split and energy spacings increase with increase of the radius.

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A Deep Improved Particle Filter for Non-linear Noisy Observation Series JIA Meng 2013, 30(3): 469-474.  Abstract ( )   PDF (1274KB) ( )   We present a deep improved particle filtering theory which selects samples from comparison of both weight increasing trend and weight.It decides fission and reproduction of samples through statistic analysis of samples.Though approaches increase computing time for trend judging,computing accuracy is improved.