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25 July 2014, Volume 31 Issue 4 Previous Issue    Next Issue

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Computational Electromagnetics and Applications in Numerical Simulation of Electromagnetic Environmental Effects and Development Tendency ZHOU Haijing, LIU Yang, LI Hanyu, DONG Ye, LIAO Cheng, DONG Zhiwei, MO Zeyao 2014, 31(4): 379-389.  Abstract ( )   PDF (1859KB) ( )   A brief introduction to development history of computational electromagnetics(CEM) and numerical methods in CEM is provided. In addition, we discuss up-to-date progress of CEM in scientific researches, commercial softwares and proprietary softwares. Considering applications of electromagnetics environmental effects (E3), we present development of our numerical simulation platform of E3. Finally, future trends of development in E3 are shown.

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Approximation and Two-level Algorithm of Finite Volume Schemes for Diffusion Equations with Structured AMR SHU Shi, YUE Xiaoqiang, ZHOU Zhiyang, XU Xiaowen 2014, 31(4): 390-402.  Abstract ( )   PDF (1353KB) ( )   We analyze approximation and propose a two-level algorithm for finite volume schemes of diffusion equations with structured adaptive mesh refinement. First of all, a typically conservative finite volume scheme was discussed, along with criterion for refining and coarsening interpolation operator. Secondly, non-conforming elements around coarse-fine interface were eliminated by introducing auxiliary triangle elements. A symmetric finite volume element (SFVE) scheme was designed. And further analysis showed the scheme has better approximation. It weakens restrictions. Finally, a two-level algorithm was constructed for SFVE. Theoretical analysis and numerical experiments demonstrate uniform convergence of the algorithm.

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Application of Gas-Kinetic Unified Algorithm Covering Various Flow Regimes for Rotational Non-equilibrium Effect JIANG Xinyu, LI Zhihui, WU Junlin 2014, 31(4): 403-411.  Abstract ( )   PDF (1805KB) ( )   With gas-kinetic unified algorithm (GKUA) based on Boltzmann equation for various flows regimes, rotational non-equilibrium effect is investigated in Rykov model, in which spin movement of gas molecules is described with moment of inertia. Numerical method of Boltzmann model equation involving rotational non-equilibrium effect is developed. Nitrogen shock wave structure, flows around a 2D blunt-head body and flows around a 3D tine bicone are simulated to validate the method in various flows regimes.

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A Model of Single Delta Oxygen Cryosorption XUE Shesheng, LI Shouxian, LIU Yang 2014, 31(4): 412-416.  Abstract ( )   PDF (669KB) ( )   Cryosorption of oxygen produced in chemical oxygen iodine laser(COIL) is considered. From the view point of mass conservation, a linear relation between gas pressure gradient and gas velocity is used with which gases flows through a zeolite porous bed is obtained. An adsorption balance equation, describing relation of components in gas flow and adsorped components,is established with adsorption dynamics equation. Henry relation is employed as isothermal equation. A set of cryosorption model equations is solved numerically. Oxygen concentration evolution,and long time character of concentrations are given.

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Flight Path Selection in Monte Carlo Code ITR for Ion Transport YANG Xin, WANG Guanbo, LI Rundong, LIU Hangang, WANG Kan 2014, 31(4): 417-423.  Abstract ( )   PDF (1012KB) ( )   Strategy of detailed history method is summarized, depending on which code ITR(ions transport and reaction) was developed. Both basic method and impulse approximation method to select flight path of ions are complemented respectively. Numerical results agree with CORTEO and TRIM very well. Relation between two methods is discussed. We found reason of CORTEO results differ from TRIM's by limiting maximum of flight length derived by impluse approximation method. ITR has advantages of TRIM and CORTEO. Impluse approximation method reduces nuclear collisions simulated. Index technique is used to calculate scattering angle, which significantly improves efficiency of ITR.

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Uncertainty Quantification of Numerical Simulation for Reliability Analysis MA Zhibo, LI Haijie, YIN Jinwei, HUANG Wenbin 2014, 31(4): 424-430.  Abstract ( )   PDF (698KB) ( )   According to demands of uncertainty quantification for reliability certification, in hierarchy of complex engineering system and development from calibration, verification & validation to prediction ability of modeling & simulation (M&S), the principle and method of uncertainty quantification of M & S are investigated. An example on detonation process is shown in which the ideas are demonstrated.

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Stability of Thin Droplet Spreading Driven by Soluble Surfactant LI Chunxi, JIANG Kai, YE Xuemin 2014, 31(4): 431-443.  Abstract ( )   PDF (2393KB) ( )   For process of an ultrathin surfactant-laden droplet spreading on preset film, base state and disturbance evolution equations for film thickness, surfactant interfacial and bulk concentrations were established with lubrication approximation. Transient growth analysis (TGA) was carried out to investigate stability of evolution process. Effects of surfactant solubility and typical parameters were discussed. TGA indicates that introduction of perturbation wave is conducive to enhance stability of droplet evolution and stability degree is directly related with wave number (k). However, stability tends to be deteriorated with increment of k. Compared with insoluble surfactant, evolution with soluble surfactant slows down slightly and stability is improved. Increasing of b, M, C, Ks stabilize the spreading, especially Marangoni effect and capillary force. Thickness of preset film has a primarily role on stability of droplet thickness evolution.

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Seismic Response of Anisotropic Coal Based on Ray Theory LI Qin, LI Qingchun, ZHANG Lin 2014, 31(4): 444-448.  Abstract ( )   PDF (921KB) ( )   We illustrate a technique of ray tracing by shooting method and analyze rules of ray in VTI coal. With mixed-language programming of VC ++ and Fortran, ray tracing in VTI coal with a complex velocity model is realized. It demonstrates necessaries of anisotropic ray tracing in VTI coal by comparison of ray tracing in VTI coal and isotropic media. By contrast of calculation time, it indicates that this method is efficient to meet needs of seismic records forward. The technique can be used in multi-wave ray tracing in anisotropic coal as giving responding formulae and parameters.

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New Algorithm for Thermophysical Parameters and Heat Loss along Wellbore During Steam Injection GU Hao, CHENG Linsong, HUANG Shijun 2014, 31(4): 449-454.  Abstract ( )   PDF (972KB) ( )   Traditional equation of steam quality is improved based on definition. Rate of wellbore heat loss is calculated with both depth step and time step. Drift-flux model of two-phase flow by Hasan is used to estimate pressure drop in wellbore. It indicates that results of modified model and new algorithm agree well with field date. They are more accurate than Beggs-Brill method. In addition, steam pressure, temperature and quality are almost unchanged at the same depth. However, rate of wellbore heat loss decreases with injection time. The algorithm provides a reference for accurate calculation of wellbore heat loss.

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Numerical Simulation of Fluid-Solid Coupling in Fractured Stress-sensitive Reservoirs WU Junlai, LIU Yuetian, LUO Jie 2014, 31(4): 455-464.  Abstract ( )   PDF (1803KB) ( )   With dynamic coupling model of fractured anisotropic full-tensor permeability, a complete three-dimensional three-phase fluid-solid coupling model for anisotropic ultra-low permeability reservoir is established. Using modular explicit coupling iteration, we establish a fluid & solid coupling seepage numerical simulation method considering fracture deformation and corresponding coupling program. It shows that for fractured reservoir, with change of reservoir pressure in process of mining, rock deformation and anisotropy of reservoir medium strain can make various deformation degree in multiple sets of cracks, cause nonlinear change of fracture permeability, which makes principal value of reservoir fracture permeability tensor rotating, changing flow direction, affecting reservoir development effect.

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Seismic Data Repair Technology Based on Diffusion Filtering Method CHEN Keyang, CHEN Shumin, LI Lailin, WU Qingling, FAN Xingcai, LIU Zhenkuan, WANG Jianmin 2014, 31(4): 465-470.  Abstract ( )   PDF (2950KB) ( )   We introduce figure repair technology based on partial differential equation into seismic data digital processing, and put forward seismic data repair technology based on diffusion filtering method. The technology diffuses undamaged area's data to data to be repaired using diffusion filtering method with a certain diffusion function. In each iteration, only the data to be repaired is updated, and undamaged area' s data is remained unchanged. Final iteration termination condition can be ensured by comparing difference with threshold before and after iterations. Two application examples of seismic data interpolation processing and seismic data local repair processing show that the technology can achieve the purpose of repairing seismic data. It recovers effectively lost seismic wave field information. Therefore, it can be used in practical seismic data digital processing.

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Phase-Field-Crystal Modeling of Microcrack Propagation and Branching in Ductile Materials GAO Yingjun, LUO Zhirong, DENG Qianqian, HUANG Lilin, LIN Kui 2014, 31(4): 471-478.  Abstract ( )   PDF (2210KB) ( )   Morphology of microcrack propagation and crack branching of single crystal ductile materials under tensile are simulated with phase-field-crystal method. It shows that shape of notch has a strong effect on crack propagation. With uniaxial tension crack propagation appears if only strain reaches a critical value. With biaxial tension a crack branches if only strain reaches a critical value. Temperature parameter takes significant effects on crack propagation. The smaller the temperature parameter is (the temperature is higher), the faster the cracks propagate and the more the crack branches are. It is observed that free energy of system decreases with time and decreases faster after crack starts to branch. During crack propagation, disconnectedly isolated cavities around the main cracks can be found and these defects become new cracks. They grow up along a line and become a branching crack. Simulated results are in agreement with other simulations and experimental results.

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Particle Swarm Optimization and Genetic Algorithm for a Relativistic Backward Wave Oscillator WANG Huihui, LIU Dagang, MENG Lin, LIU Laqun 2014, 31(4): 479-485.  Abstract ( )   PDF (1691KB) ( )   Based on platform of three-dimensional particle-in-cell (PIC), CHIPIC, modules of particle swarm optimization (PSO) and genetic algorithm (GA) are designed to optimize a relativistic backward wave oscillator (RBWO), respectively. Comparisons of PSO and GA are implemented in three kinds of parameters of RBWO:Continuous parameter, discrete parameter, and mix parameters. It shows that performances of PSO are better than that of GA. PSO has higher optimization accuracy and convergence rate than GA.

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A Comparative Study on Structure and Electronic Properties of ZnO/ZnS Heteronanowires CHEN Hongxia, XIE Jianming 2014, 31(4): 486-494.  Abstract ( )   PDF (2149KB) ( )   We study systematically structural and electronic properties of ZnO/ZnS superlattice nanowires and core-shell structural ZnO/ZnS nanowires with first-principles calculations. Relaxed structures of these heterostructural nanowires are found similar to those of homogeneous ZnO and ZnS nanowires. Band structures of heteronanowires show that they are direct-band gap semiconductors. For ZnO/ZnS superlattice nanowires, bands become flatter with the formation of minibands. For core-chell ZnO/ZnS nanowires, PDOS show that they are type-Ⅱ heterostructures. These may be important in understanding structural and electronic properties of heterostructural nanowires and their utilization in electric generator and photovoltaic devices.

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Growing 2D Manifold of Discrete Dynamical System Based on Foliation Condition JIA Meng 2014, 31(4): 495-504.  Abstract ( )   PDF (1629KB) ( )   An algorithm for computing 2D stable and unstable manifolds of hyperbolic fixed points of discrete dynamical systems is shown. With the fact that Jacobian transports derivative along orbit of an invariant manifold, an algorithm for computing 1D manifold is proposed. The mesh point is located with a Prediction-Correction scheme which reduces searching time and at the same time gives rise to a simplified accuracy condition. 2D manifold is computed by covering it with orbits of 1D sub-manifold. A generalized Foliation condition is used to guarantee that 2D manifold is growing equally along orbits of 1D sub-manifold in different directions. Performance of the algorithm is demonstrated with hyper chaotic 3D Hénon map and Lorenz system.