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25 March 2019, Volume 36 Issue 2 Previous Issue    Next Issue

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On Statistical Spectral Property of Nonlinear Weights in High Order Schemes LI Li, LIU Xiaoyan, LI Xinliang, TIAN Baolin, LIANG Xian, HA Jincai 2019, 36(2): 127-140.  DOI: 10.19596/j.cnki.1001-246x.7812 Abstract ( )   HTML ( )   PDF (2000KB) ( )   Fourier property of nonlinear weights and limiters in wave-space are analyzed. Firstly, a statistical method is designed to analyze Fourier property of nonlinear weights. Secondly, averaged values and deviations of nonlinear weights are shown, and values with change of wave-number are analyzed. It is helpful to comprehension of nonlinear schemes. The method is a guidance for designing shock-capture schemes.

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A High Order Accuracy Corrected Hermite-ENO Scheme GUO Zitao, FENG Renzhong 2019, 36(2): 141-152.  DOI: 10.19596/j.cnki.1001-246x.7819 Abstract ( )   HTML ( )   PDF (4072KB) ( )   A kind of sixth order accuracy ENO scheme with 3 units based on corrected Hermite polynomials, named CHENO scheme, is proposed for one-dimensional hyperbolic conservation laws. Space discrete of CHENO scheme is based on finite volume formulation. In space layer, it chooses templates with Newton difference method in ENO scheme. Reconstruction of function and its first derivative in the half node based on Hermite interpolation are corrected to improve accuracy to sixth order by Taylor expansion. We proposed a discontinuous recognition method to control oscillation in discontinuous points. In time layer, both function and its first derivative of CHENO scheme are evolved in time by using 3rd TVD Runge-Kutta schemes. Major advantage of CHENO scheme is higher order accuracy and compactness. Numerical experiments on one-dimensional hyperbolic conservation laws validated feasibility of CHENO scheme.

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Interfacial Dynamics of Immiscible Gas-Liquid Two-phase Flow for CO2 in Microchannel: Lattice Boltzmann Method LOU Qin, ZANG Chenqiang, WANG Haoyuan, LI Ling 2019, 36(2): 153-164.  DOI: 10.19596/j.cnki.1001-246x.7839 Abstract ( )   HTML ( )   PDF (3539KB) ( )   An accurate equation of state (EOS) for carbon dioxide is coupled into an improved lattice Boltzmann equation (LBE) model. With the model continuous interfacial dynamics of carbon dioxide in two phase in a microchannel, including breaking up, coalescence, deformation, and mass exchange between gas and liquid phases, is studied. It is found that flows achieve a steady-state as balance of breaking up and coalescence is reached, and mass exchange occurs. Comprehensive results show that flow shape at steady-state depends mainly on surface tension, inertial force, wettability of channel surface, and initial volume fraction. Specially, formative bubbles or droplets are almost spherical as inertial force is smaller than surface tension. As surface tension overcomes inertial force, slug flow is formed since bubbles or droplets are easy to expand to contact with solid surface. On the other hand, it shows that influence of wettability on flow pattern is also important. Slug flow is observed if contact angle is small while annular flow is observed if contact angel is large. At different volume fraction slug flow and annular flow are obtained.

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Moving Shock Interacting with Cylindrical Water Columns and a Nozzle Flow Field: rGFM and Level-Set Method DING Shengrong, XU Shengli, LU Jianfang, ZHANG Mengping 2019, 36(2): 165-174.  DOI: 10.19596/j.cnki.1001-246x.7842 Abstract ( )   HTML ( )   PDF (13394KB) ( )   Flow field induced by a moving shock interacted with cylindrical water columns and a nozzle flow field was numerically investigated. Fixed Cartesian grids are used and level-set method combined with revised real ghost fluid method (rGFM) is applied for tracking gas-water and gas-solid interfaces. Fifth order WENO schemes are employed for solving Eulerian and level-set equations as well as reinitialization equations. Nozzle contours are simplified as gas-solid interface, and nozzle contour profiles are expressed by splines for ease of obtaining normal vector. In the case of shock interacting with water columns, schlieren images and pressure time histories at specified points are shown to describe shock evolution and mitigation downstream. It indicates that complex shock structures are distinguished accurately by the method, and shock transmission and reflection occur on gas-water interfaces of neighboring columns in a row and in a column respectively. In addition, pressure, density contours and velocity of nozzle flow field is in agreement with inviscid solution by gas dynamics theory, which demonstrates effectiveness and robustness of level-set method coupling with rGFM for computing flow field in a complex geometry involving gas-water and gas-solid interfaces.

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Analysis of Steady Cross-flow Instability Transition in Infinite Swept Wing Boundary Layer CAI Linfeng, LI Haoge, CHEN Weifang 2019, 36(2): 175-181.  DOI: 10.19596/j.cnki.1001-246x.7830 Abstract ( )   HTML ( )   PDF (3436KB) ( )   γ-Reθt crossflow extension model was applied to conduct numerical simulation of crossflow transition on NLF(2)-0415 infinite swept wing. Effects of Reynolds number, surface roughness, sweep angle on crossflow instability of 3-D boundary layer were studied mainly. It found that γ-Reθt crossflow extension model predicts 3-D boundary layer transition correctly and calculation results agree well with experiment data. It shows that with increase of Reynolds number or surface roughness, location of crossflow transition onset moves forward. However, with increase of sweep angle, location of crossflow transition onset moves forward firstly and then moves back.

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Heat Transfer and Phase Change of Laser Irradiated Gold Particle with Scattering Effect HE Yunlong, LI Ling 2019, 36(2): 182-188.  DOI: 10.19596/j.cnki.1001-246x.7827 Abstract ( )   HTML ( )   PDF (1869KB) ( )   Phase change heat transfer of a gold particle irradiated by ulter-fast laser was studied. Position of solid-liquid interface was determined with coupling interface energy balance equation and interface tracking method for nucleation dynamics. In addition, effects of laser parameters on sintering process were studied. It showed that as laser irradiates gold particle vertically, melting phenomenon occurs mainly in poles of particle. Bottom of particle melts earlier than top and melting volume is smaller. As laser pulse width becomes shorter melting is earlier and melting volume increases. Melting degree of particle increases with laser heat source fluence.

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Simulation of Polarization Characteristics and Attenuation of Dual-polarization Rain-measuring Radar with T-matrix Methods FENG Liang, XIAO Hui, LUO Li 2019, 36(2): 189-202.  DOI: 10.19596/j.cnki.1001-246x.7826 Abstract ( )   HTML ( )   PDF (25021KB) ( )   We investigate polarization and attenuation characteristics of X,C and S bands of dual-polarization radars with monodisperse raindrops of equivalent spherical diameter, different rainfall intensities and different maximum raindrops diameters using by T-matrix scattering simulation. Attenuation correction relation of radar reflectivity and differential reflectivity is established for the three bands of dual-polarization radars in medium of rain. Finally, accuracy of the scattering simulation results is verified by measured raindrop spectrum data and measured reflectivity data of X-band dual-polarization radar.

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Influence of Local Heat Source on Thermal Transport in Magnetic Island LIU Yongqiang, ZHA Xuejun, WANG Qingsong, YANG Zhen, XIA Qinghao, WU Bin 2019, 36(2): 203-210.  DOI: 10.19596/j.cnki.1001-246x.7816 Abstract ( )   HTML ( )   PDF (11620KB) ( )   We study heat transport in magnetic island in Tokamak. As electron cyclotron resonance heating (ECRH) has good locality it is used to simulate ECRH plasmas for local Gaussian heat source in magnetic island. In the case of simultaneous existence of background heat source and local Gaussian heat source, variation of radial electron temperature distribution and heat transport in local Gaussian heat source are studied. Analysis is made on influence of local Gaussian heat source on temperature perturbation and magnetic island constraint energy.

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Molecular Dynamics Study of Mechanical Properties of Single Crystal Aluminum with Voids and Vacancies LIANG Hua, LI Maosheng 2019, 36(2): 211-218.  DOI: 10.19596/j.cnki.1001-246x.7818 Abstract ( )   HTML ( )   PDF (21639KB) ( )   Molecular dynamics simulations are performed for single crystal aluminum with voids and vacancies under uniaxial tension. Effects of crystalline orientation,initial void volume fraction,and concentration of vacancies on growing process of voids are investigated. It indicates that at different orientation, decisive microscopic machanism of void growing is different. At orientation[010], decisive machanism is stacking fault caused by dislocations on {111} surface, while at orientation[111], decisive machanism is movement and accumulation of dislocations.Besides, initial void volume fraction and concentration of vacancies have remarkable influence on growing precess of voids.Totally, macroscopic effective Young's modulus and incipient yield strength decrise with increasing void volume fraction or concentration of vacancies.

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Structure and Properties of (BN)25 Clusters HE Zhiwei, ZHANG Xiurong 2019, 36(2): 219-224.  DOI: 10.19596/j.cnki.1001-246x.7835 Abstract ( )   HTML ( )   PDF (2120KB) ( )   Geometries, stabilities, NBO, vibrational spectroscopy and NICS of (BN)25 clusters were optimized in the framework of density functional theory (DFT) through the use of B3LYP hybrid functional associated with 6-31G(d) basis sets. We found that (BN)25 clusters is stable due to its large average binding energy and energy gap. Charge transfer and s, p hybridization between adjacent B and N atoms are confirmed by NBO analysis. Many vibration peaks are found in infrared spectrum and Raman spectra. Negative nucleus independent chemical shifts(NICS) indicate that BN clusters have aromatic properties.

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Global Optimization of Heat Exchanger Network Based on Structure Diversity Evaluation BAO Zhongkai, CUI Guomin, XIAO Yuan, CHEN Jiaxing 2019, 36(2): 225-235.  DOI: 10.19596/j.cnki.1001-246x.7838 Abstract ( )   HTML ( )   PDF (1980KB) ( )   Individual gathering could cause decline of search ability as heuristic methods are applied to heat exchanger network (HEN) optimization. An evaluation methodology for HEN structure diversity was designed to measure degree of individual structure gathering, and guided algorithm improvement. Firstly, group division of population was performed, individuals of a certain scale with a common structure were classified as a group to get individual structure distribution. Then dispersal search strategy was proposed to give perturbation to heat exchangers randomly selected from common structure of individuals in each group except the best one, which aimed at dispersing individual structures in groups. Concentration search strategy was then proposed to enhance exploitation for excellent structure by making other individuals accept a common structure of the optimal group. Finally, two cases involving nine and fifteen streams proved that dispersal search strategy strengthened global search ability and concentration search strategy strengthened local search ability. It obtained results decreased by 7 008 $·a-1 and 17 973 $·a-1, respectively, compared to those obtained by original algorithm. They are superior to results in literature.

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Synchronization and Parameter Identification of Chaotic Systems Based on Quantum-Behaved Particle Swarm Optimization SHI Jianping, YANG Lantian, LIU Dan 2019, 36(2): 236-244.  DOI: 10.19596/j.cnki.1001-246x.7809 Abstract ( )   HTML ( )   PDF (4227KB) ( )   For synchronization cotrol of chaotic systems with different structures and unkown parameters, synchronization controller is designed and stability of error system is analyzed theoretically. With reasonably selected optimization objective function and quantum-behaved particle swarm optimization, unknown parameters identification of chaotic system are realized, which reduces effectively development difficulty of the synchronization controller. Synchronization between Rössler chaotic system and Lorenz chaotic system is studied, and numerical experiments are carried out. It shows that the proposed method achieves fast synchronization of drive-response system and accurate identification of unknown system parameters, which verifies feasibility and effectiveness of the method.

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Dynamical Stability of Solitary Wave Propagation in Inhomogeneous Cylindrical Shells Naranmandula, Chilimuge 2019, 36(2): 245-252.  DOI: 10.19596/j.cnki.1001-246x.7844 Abstract ( )   HTML ( )   PDF (5136KB) ( )   Dynamical stability of solitary wave propagation in inhomogeneous cylindrical shell was numerically studied in detail by using method of integrating factors. Stable propagation keeping structure of waveform and propagation speed of solitary wave for long time was examined, under three kinds of initial perturbations that is Gaussian wave perturbation, harmonic wave perturbation and stochastic perturbation. It shows that stable propagation of solitary wave is related to amplitude, width and wavelength of perturbations. Only with small enough amplitude, width and wavelength, solitary wave shows relatively strong anti-interference property, and has better dynamical stability.