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Nuclear Science and Techniques 2021年第8期32卷 95-109页

作者： Ming Dai Mao-Song Cheng Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China CAS Innovative Academies in TMSR Energy System Chinese Academy of SciencesShanghai 201800China

The algebraic collapsing acceleration(ACA)technique maximizes the use of geometric flexibility of the method of characteristics(MOC).The spatial grids for loworder ACA are the same as the high-order transport,which makes the numerical solution of ACA equations costly,especially for large-size *** speed-up the MOC transport iterations effectively for general geometry,a coarse-mesh ACA method that involves selectively merging fine-mesh cells with identical materials,called material-mesh ACA(MMACA),is *** energy group batching(EGB)strategy in the tracing process is proposed to increase the parallel efficiency for microscopic crosssection *** and macroscopic crosssection benchmark problems are used to validate and analyse the accuracy and efficiency of the MMACA *** maximum errors in the multiplication factor and pin power distributions are from the VERA-4 B-2 D case with silver-indium-cadmium(AIC)control rods inserted and are 104 pcm and 1.97%,*** with the single-thread ACA solution,the maximum speed-up ratio reached 25 on 12 CPU cores for microscopic cross-section VERA-4-2 D *** the C5 G7-2 D and LRA-2 D benchmarks,the MMACA method can reduce the computation time by approximately one *** present work proposes the MMACA method and demonstrates its ability to effectively accelerate MOC transport iterations.

关键词： Algebraic collapsing acceleration Material-mesh ACA method of characteristics OpenMP Arbitrary geometry

Preliminary study on CAD-based method of characteristics for neutron transport calculation

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Chinese Physics C 2014年第5期38卷 114-120页

作者：陈珍平郑华庆孙光耀宋婧郝丽娟胡丽琴吴宜灿 University of Science and Technology of China Institute of Nuclear Energy Safety Technology Chinese Academy of Sciences

Our new method makes use of a CAD-based automatic modeling tool, MCAM, for geometry modeling and ray tracing of particle transport in method of characteristics （MOC）. It was found that it could considerably enhance the capability of MOC to deal with more complicated models for neutron transport calculation. In our study, the diamond-difference scheme was applied to MOC to reduce the spatial discretization errors of the fiat flux approximation. Based on MCAM and MOC, a new 2D MOC code was developed and integrated into the SuperMC system, which is a Super Multi-function Computational system for neutronics and radiation simulation. The numerical results demonstrated the feasibility and effectiveness of the new method for neutron transport calculation in MOC.

关键词： method of characteristics neutron transport calculation CAD geometry modeling

DOUBLE method of characteristics TO ANALYZE HYDRAULIC-THERMAL TRANSIENTS OF PIPELINE FLOW

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Applied Mathematics and Mechanics(English Edition) 2002年第6期23卷 703-711页

作者：邓松圣周明来蒲家宁 Department of Petroleum Supply Engineering Chongqing College of Logistic Engineering 400016 Chongqing P R China

The hydraulic and thermal transients in pipeline flow were studied. The method of characteristics for hydraulic transient analysis of batch transport of pipeline flow had been improved. The thermal transient equation, in which the term with v 3 was involved, had been inferred, while the corresponding method of characteristics was constructed. The double method of characteristics, which can be used to study the coherent hydraulic-thermal transients of batch transport of pipeline flow, was developed.

关键词： pipeline flow thermal transient hydraulic transient method of characteristics

NUMERICAL SOLUTION OF FLUID-STRUCTURE INTERACTION IN LIQUID-FILLED PIPES BY method of characteristics

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Chinese Journal of Mechanical Engineering 2007年第3期20卷 44-49页

作者： YANG Chao YI Menglin College of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China School of Mechatronic Engineering East China Jiaotong University Nanchang 330013 China College of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan 430074. China

Fluid-structure interaction （FSI） is essentially a dynamic phenomenon and always exists in fluid-filled pipe system. The four-equation model, which has been proved to be effective to describe and predict the phenomenon of FSI due to friction coupling and Poisson coupling being taken into account, is utilized to describe the FSI of fluid-filled pipe system. Terse compatibility equations are educed by the method of characteristics （MOC） to describe the fluid-filled pipe system. To shorten computing time needed to get the solutions under the condition of keeping accuracy requirement, two steps are adopted, firstly the time step Δt and divided number of the straight pipe are optimized, sec-ondly the mesh spacing Δz close to boundary is subdivided in several submeshes automatically ac-cording to the speed gradient of fluid. The mathematical model and arithmetic are validated by com-parisons between simulation solutions of two straight pipe systems and experiment known from lit-erature.

关键词： Fluid-structure interaction method of characteristics Coupling Fluid-filled pipe system Optimization

Simulating advance distance in border irrigation systems based on the improved method of characteristics

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International Journal of Agricultural and Biological Engineering 2021年第3期14卷 156-162页

作者： Kaihua Liu Xiyun Jiao Weihua Guo Mohamed Khaled Salahou Zhe Gu College of Hydrology and Water Resources Hohai UniversityNanjing 210098China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing 210098China College of Agricultural Science and Engineering Hohai UniversityNanjing 210098China Cooperative Innovation Center for Water Safety and Hydro Science Hohai UniversityNanjing 210098China

Improving the simulation accuracy of the advance distance based on the method of characteristics is essential to develop numerical solutions for simulating surface *** of volume balance in the traditional method of characteristics(T-MC),the position of critical flow is determined to simulate the advance distance in the improved method of characteristics(I-MC),which is used in border irrigation systems with rapid variation in inflow discharge in the current ***,the zones of both subcritical and supercritical flow were firstly distinguished to determine the position of the critical flow point,which was also the upstream boundary of the wetting front region,and then the advance distance was calculated by applying the diffusive wave equation in the wetting front *** results showed that the I-MC accurately simulated the advance distance with high determination coefficients(0.984-0.998)and low errors(root mean square error of 0.35-1.56 min and coefficient of residual mass of 0.01-0.06),which performed much better than the *** I-MC provided a suitable and simple numerical simulation tool to improve the establishment of numerical surface irrigation models.

关键词： border irrigation numerical solution advance distance method of characteristics

An Accurate Numerical Scheme for Maxwell Equation with CIP-method of characteristics

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Communications in Computational Physics 2006年第2期1卷 311-335页

作者： Youichi Ogata Takashi Yabe Kouichi Odagaki Department of Mechanical Sciences and Engineering Tokyo Institute of Technology2-12-1 Meguro-kuOokayama 152-8552Japan

A new multi-dimensional scheme for the Maxwell equations is established by the CIP method in combination with the method of characteristics(CIP-MOC).In addition,the CIP-MOC can be extended to arbitrary grid system by the Soroban grid without losing the third-order *** the accuracy fixed,the grid points required for the CIP are 40 times less than the conventional schemes like the FDTD in three *** solutions obtained by the CIP-MOC are compared with analytical solution and the FDTD in plane-wave scattering by a perfectly-conducting circular cylinder,and the CIP-MOC agrees very well with analytical *** Soroban grid is also applied to the Vlasov equation that describes the kinematics of plasmas that is frequently combined with the Maxwell *** adaptively moving points in velocity space are similar to the particle codes but can provide accurate solutions.

关键词： Maxwell equation Vlasov equation CIP method method of characteristics Soroban grid

A hybrid CFD/characteristics method for fast characterization of hypersonic blunt forebody/inlet flow

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Science China(Physics,Mechanics & Astronomy) 2015年第10期58卷 38-45页

作者： GAO WenZhi LI ZhuFei YANG JiMing Department of Modern Mechanics University of Science and Technology of China

A hybrid CFD/characteristic method(CCM) was proposed for fast design and evaluation of hypersonic inlet flow with nose bluntness, which targets the combined advantages of CFD and method of characteristics. Both the accuracy and efficiency of the developed CCM were verified reliably, and it was well demonstrated for the external surfaces design of a hypersonic forebody/inlet with nose bluntness. With the help of CCM method, effects of nose bluntness on forebody shock shapes and the flowfield qualities which dominate inlet performance were examined and analyzed on the two-dimensional and axisymmetric configurations. The results showed that blunt effects of a wedge forebody are more substantial than that of related cone cases. For a conical forebody with a properly blunted nose, a recovery of the shock front back to that of corresponding sharp nose is exhibited, accompanied with a gradually fading out of entropy layer effects. Consequently a simplification is thought to be reasonable for an axisymmetric inlet with a proper compression angle, and a blunt nose of limited radius can be idealized as a sharp nose, as the spillage and flow variations at the entrance are negligible, even though the nose scale increases to 10% cowl lip radius. Whereas for two-dimensional inlets, the blunt effects are substantial since not only the inlet capturing/starting capabilities, but also the flow uniformities are obviously degraded.

关键词： hypersonic flow shock wave forebody/inlet flow nose bluntness method of characteristics

A novel approach for predicting inlet pressure of aircraft hydraulic pumps under transient conditions

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Chinese Journal of Aeronautics 2019年第11期32卷 2566-2576页

作者： Yan WANG Hongkang DONG Yongling HE School of Transportation Science and Engineering Beihang University

Cavitation caused by insufficient suction is a major factor that influences the life of aircraft pumps. Currently, pressurizing the tank can solve the cavitation problem under steady largeflow conditions. However, this method is not always effective under transient conditions(from zero flow to full flow in a very short time). Moreover, to apply and design other measures, such as a boost impeller, the suction dynamics during the transient period must be investigated. In this paper,a novel approach based on the pressure wave propagation theory is proposed for predicting the inlet pressure of an aircraft pump under transient conditions. First, a dynamic model of a typical aircraft pump is established in the form of differential equations. Then, the transient flow model of the inlet line is described using momentum and continuity equations, and the governing equations are discretized by the method of characteristics and the finite difference method. The simulated results are in good agreement with the results from verification tests. Further simulation analysis indicates that the wave velocity and transient time may influence the inlet and reservoir pressure as well as the size of the inlet line. Finally, solutions for upgrading the inlet pressure are discussed. These solutions provide guidelines for designing inlet installations.

关键词： Aircraft hydraulic pump Boost impeller Inlet pressure method of characteristics Transient condition Wave propagation

Supersonic Two-Dimensional Minimum Length Nozzle Design at High Temperature. Application for Air

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Chinese Journal of Aeronautics 2007年第1期20卷 29-39页

作者： Toufik Zebbiche ZineEddine Youbi Department of Aeronautics Faculty of Sciences of Engineer University SAAD Dahleb of Blida B.P. 270 Ouled Yaich 09470 Blida Algeria.

When the stagnation temperature of a perfect gas increases, the specific heat ratio does not remain constant any more, and start to vary with this temperature. The gas remains perfect, its state equation remains always valid, except it will name in more calorically imperfect gas or gas at High Temperature. The goal of this work is to trace the profiles of the supersonic Minimum Length Nozzle with centered expansion when the stagnation temperature is taken into account, lower than the threshold of dissociation of the molecules and to have for each exit Mach number several nozzles shapes by changing the value of the temperature. The method of characteristics is used with a new form of the Prandtl Meyer function at high temperature. The resolution of the obtained equations is done by the second order of fmite differences method by using the predictor corrector algorithm. A study on the error given by the perfect gas model compared to our model is presented. The comparison is made with a calorically perfect gas for goal to give a limit of application of this model. The application is for the air.

关键词： supersonic flow minimum length nozzle calorically imperfect gas interpolation Prandtl Meyer function stretching function Simpson quadrature supersonic parameters conception method of characteristics

Design of a continuously variable Mach-number nozzle

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Journal of Central South University 2015年第2期22卷 522-528页

作者：郭善广王振国赵玉新 Science and Technology on Scramjet Laboratory National University of Defense Technology

A design method was developed to specify the profile of the continuously variable Mach-number nozzle for the supersonic wind tunnel. The controllable contour design technique was applied to obtaining the original nozzle profile, while other Machnumbers were derived from the transformation of the original profile. A design scheme, covering a Mach-number range of3.0method, computational fluid dynamics(CFD) analyses were carried out to study the flow quality in the test area of the nozzle. The computed results indicate that exit uniform flow is obtained with 1.19% of the maximal Mach-number deviation at the nozzle exit. The present design method achieves the continuously variable Mach-number flow during a wind tunnel running.

关键词： wind tunnel variable Mach-number nozzle flow quality method of characteristics numerical validation