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A High-Order Numerical Method Based on Legendre Polynomial Approximation for Fourth-Order Eigenvalue Problem in Cylinder Domain
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作者 Jun ZHANG Jihui ZHENG Fangying SONG 《Journal of Mathematical Research with Applications》 2025年第2期195-219,共25页
In this work, an efficient spectral method is proposed to solve the fourth-order eigenvalue problem in cylinder domain. Firstly, the key point of this method is to decompose the original model into a kind of decoupled... In this work, an efficient spectral method is proposed to solve the fourth-order eigenvalue problem in cylinder domain. Firstly, the key point of this method is to decompose the original model into a kind of decoupled two-dimensional eigenvalue problem by cylindrical coordinate transformation and Fourier series expansion, and deduce the crucial essential pole conditions. Secondly, we define a kind of weighted Sobolev spaces, and establish a suitable variational formula and its discrete form for each two-dimensional eigenvalue problem. Furthermore, we derive the equivalent operator formulas and obtain some prior error estimates of spectral theory of compact operators. More importantly, we further obtained error estimates for approximating eigenvalues and eigenfunctions by using two newly constructed projection operators. Finally,some numerical experiments are performed to validate our theoretical results and algorithm. 展开更多
关键词 fourth-order equation decoupled reduced-dimension formulation Legendre-Galerkin method error estimate cylinder domain
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An efficient and accurate numerical method for simulating close-range blast loads of cylindrical charges based on neural network
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作者 Ting Liu Changhai Chen +2 位作者 Han Li Yaowen Yu Yuansheng Cheng 《Defence Technology(防务技术)》 2025年第2期257-271,共15页
To address the problems of low accuracy by the CONWEP model and poor efficiency by the Coupled Eulerian-Lagrangian(CEL)method in predicting close-range air blast loads of cylindrical charges,a neural network-based sim... To address the problems of low accuracy by the CONWEP model and poor efficiency by the Coupled Eulerian-Lagrangian(CEL)method in predicting close-range air blast loads of cylindrical charges,a neural network-based simulation(NNS)method with higher accuracy and better efficiency was proposed.The NNS method consisted of three main steps.First,the parameters of blast loads,including the peak pressures and impulses of cylindrical charges with different aspect ratios(L/D)at different stand-off distances and incident angles were obtained by two-dimensional numerical simulations.Subsequently,incident shape factors of cylindrical charges with arbitrary aspect ratios were predicted by a neural network.Finally,reflected shape factors were derived and implemented into the subroutine of the ABAQUS code to modify the CONWEP model,including modifications of impulse and overpressure.The reliability of the proposed NNS method was verified by related experimental results.Remarkable accuracy improvement was acquired by the proposed NNS method compared with the unmodified CONWEP model.Moreover,huge efficiency superiority was obtained by the proposed NNS method compared with the CEL method.The proposed NNS method showed good accuracy when the scaled distance was greater than 0.2 m/kg^(1/3).It should be noted that there is no need to generate a new dataset again since the blast loads satisfy the similarity law,and the proposed NNS method can be directly used to simulate the blast loads generated by different cylindrical charges.The proposed NNS method with high efficiency and accuracy can be used as an effective method to analyze the dynamic response of structures under blast loads,and it has significant application prospects in designing protective structures. 展开更多
关键词 Close-range air blast load Cylindrical charge numerical method Neural network CEL method CONWEP model
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Multi-Phase Modeling for Vulnerability Detection & Patch Management: An Analysis Using Numerical Methods
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作者 Adarsh Anand Div ya +1 位作者 Deepti Aggrawal Omar H.Alhazmi 《Computers, Materials & Continua》 2025年第7期1529-1544,共16页
Software systems are vulnerable to security breaches as they expand in complexity and functionality.The confidentiality,integrity,and availability of data are gravely threatened by flaws in a system’s design,implemen... Software systems are vulnerable to security breaches as they expand in complexity and functionality.The confidentiality,integrity,and availability of data are gravely threatened by flaws in a system’s design,implementation,or configuration.To guarantee the durability&robustness of the software,vulnerability identification and fixation have become crucial areas of focus for developers,cybersecurity experts and industries.This paper presents a thorough multi-phase mathematical model for efficient patch management and vulnerability detection.To uniquely model these processes,the model incorporated the notion of the learning phenomenon in describing vulnerability fixation using a logistic learning function.Furthermore,the authors have used numerical methods to approximate the solution of the proposed framework where an analytical solution is difficult to attain.The suggested systematic architecture has been demonstrated through statistical analysis using patch datasets,which offers a solid basis for the research conclusions.According to computational research,learning dynamics improves security response and results in more effective vulnerability management.The suggested model offers a systematic approach to proactive vulnerability mitigation and has important uses in risk assessment,software maintenance,and cybersecurity.This study helps create more robust software systems by increasing patch management effectiveness,which benefits developers,cybersecurity experts,and sectors looking to reduce security threats in a growing digital world. 展开更多
关键词 Learning phenomenon numerical method PATCHING two-phase modelling VULNERABILITY
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Numerical simulation of circulating fluidization roasting desulfurization of high-sulfur bauxite based on computational particle fluid dynamics method
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作者 Langfeng Fan Chengming Xie +5 位作者 Qijin Wei Hongliang Zhao Rongbin Li Yongmin Zhang Fengqin Liu Hong Yong Sohn 《Chinese Journal of Chemical Engineering》 2025年第6期138-152,共15页
As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-s... As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-sulfur bauxite were simulated using the computational particle fluid dynamics(CPFD) method.The effect of primary air flow velocity on particle velocity,particle volume distribution,furnace temperature distribution and pressure distribution were investigated.Under the condition of the same total flow of natural gas,the impact of the number of inlets on the desulfurization efficiency,atmosphere mass fraction distribution and temperature distribution in the furnace was further investigated. 展开更多
关键词 FLUIDIZATION Circulating fluidized bed numerical simulation CPFD method Roasting desulfurization BAUXITE
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Numerical Simulation Method of Meshless Reservoir Considering Time-Varying Connectivity Parameters
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作者 Yuyang Liu Wensheng Zhou +4 位作者 Zhijie Wei Engao Tang Chenyang Shi Qirui Zhang Zifeng Chen 《Energy Engineering》 2025年第10期4245-4260,共16页
After a long period of water flooding development,the oilfield has entered the middle and high water cut stage.The physical properties of reservoirs are changed by water erosion,which directly impacts reservoir develo... After a long period of water flooding development,the oilfield has entered the middle and high water cut stage.The physical properties of reservoirs are changed by water erosion,which directly impacts reservoir development.Conventional numerical reservoir simulation methodologies typically employ static assumptions for model construction,presuming invariant reservoir geological parameters throughout the development process while neglecting the reservoir’s temporal evolution characteristics.Although such simplifications reduce computational complexity,they introduce substantial descriptive inaccuracies.Therefore,this paper proposes a meshless numerical simulation method for reservoirs that considers time-varying characteristics.This method avoids the meshing in traditional numerical simulation methods.From the fluid flow perspective,the reservoir’s computational domain is discretized into a series of connection units.An influence domain with a certain radius centered on the nodes is selected,and one-dimensional connection units are established between the nodes to achieve the characterization of the flow topology structure of the reservoir.In order to reflect the dynamic evolution of the reservoir’s physical properties during the water injection development process,the time-varying characteristics are incorporated into the formula of the seepage characteristic parameters in the meshless calculation.The change relationship of the permeability under different surface fluxes is considered to update the calculated connection conductivity in real time.By combining with the seepage control equation for solution,a time-varying meshless numerical simulation method is formed.The results show that compared with the numerical simulationmethod of the connection elementmethod(CEM)that only considers static parameters,this method has higher simulation accuracy and can better simulate the real migration and distribution of oil and water in the reservoir.Thismethod improves the accuracy of reservoir numerical simulation and the development effect of oilfields,providing a scientific basis for optimizing the water injection strategy,adjusting the production plan,and extending the effective production cycle of the oilfield. 展开更多
关键词 Meshless method parameters’time-varying numerical simulation production optimization block application
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Overview of Efficient Numerical Computing Methods Based on Deep Learning
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作者 Kejun Yang 《Journal of Electronic Research and Application》 2025年第2期117-124,共8页
This article reviews the application and progress of deep learning in efficient numerical computing methods.Deep learning,as an important branch of machine learning,provides new ideas for numerical computation by cons... This article reviews the application and progress of deep learning in efficient numerical computing methods.Deep learning,as an important branch of machine learning,provides new ideas for numerical computation by constructing multi-layer neural networks to simulate the learning process of the human brain.The article explores the application of deep learning in solving partial differential equations,optimizing problems,and data-driven modeling,and analyzes its advantages in computational efficiency,accuracy,and adaptability.At the same time,this article also points out the challenges faced by deep learning numerical computation methods in terms of computational efficiency,interpretability,and generalization ability,and proposes strategies and future development directions for integrating with traditional numerical methods. 展开更多
关键词 Deep learning Efficient numerical value method of calculation
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Numerical simulation of vortex-induced vibration of deepwater drilling riser based on discrete vortex method
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作者 Yan-Bin Wang Hong-Chuan Zhao +1 位作者 De-Li Gao Rui Li 《Petroleum Science》 2025年第5期2042-2061,共20页
Deepwater drilling riser is the key equipment connecting the subsea wellhead and floating drilling platform.Due to complex marine environment,vortex-induced vibration(ViV)will be generated on riser,which will induce f... Deepwater drilling riser is the key equipment connecting the subsea wellhead and floating drilling platform.Due to complex marine environment,vortex-induced vibration(ViV)will be generated on riser,which will induce fatigue failure and even cause unpredictable drilling accidents.Therefore,it is important to study the ViV characteristics of deepwater drilling riser and reveal the main controlling factors for ensuring the safe and efficient operation of deepwater drilling engineering.In this paper,the ViV of deepwater drilling riser is numerically simulated in time domain based on the discrete vortex method(DvM).A hydrodynamic analysis model and governing equation of VIV is proposed with considering the effect of riser motion using DVM and slice method,where the governing equation is solved by Runge-Kutta method.Model validation is performed,which verified the correctness and accuracy of the mechanical model and the solution method.On this basis,the influence of the number of control points,current velocity,riser outer diameter,shear flow and top tension on the ViV characteristics of deepwater drilling risers are discussed in detail.The results show that with the increase of current velocity,the vibration amplitude of deepwater drilling riser decreases obviously,while the vibration frequency increases gradually.However,if the outer diameter of riser increases,the vibration amplitude increases,while the vibration frequency decreases gradually.The top tension also has great influence on the VIV of riser.When the top tension is 1.25 G,the VIV is suppressed to a certain extent.This study has guiding significance for optimal design and engineering control of deepwater drilling riser. 展开更多
关键词 Deepwater drilling riser Vortex-induced vibration Discrete vortex method numerical simulation VIV suppression
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A Review of the Numerical Methods for Diblock Copolymer Melts
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作者 Youngjin Hwang Seungyoon Kang Junseok Kim 《Computers, Materials & Continua》 2025年第2期1811-1838,共28页
This review paper provides a comprehensive introduction to various numerical methods for the phase-field model used to simulate the phase separation dynamics of diblock copolymer melts.Diblock copolymer systems form c... This review paper provides a comprehensive introduction to various numerical methods for the phase-field model used to simulate the phase separation dynamics of diblock copolymer melts.Diblock copolymer systems form complex structures at the nanometer scale and play a significant role in various applications.The phase-field model,in particular,is essential for describing the formation and evolution of these structures and is widely used as a tool to effectively predict the movement of phase boundaries and the distribution of phases over time.In this paper,we discuss the principles and implementations of various numerical methodologies for this model and analyze the strengths,limitations,stability,accuracy,and computational efficiency of each method.Traditional approaches such as Fourier spectral methods,finite difference methods and alternating direction explicit methods are reviewed,as well as recent advancements such as the invariant energy quadratization method and the scalar auxiliary variable scheme are also presented.In addition,we introduce examples of the phase-field model,which are fingerprint image restoration and 3D printing.These examples demonstrate the extensive applicability of the reviewed methods and models. 展开更多
关键词 Nonlocal cahn–hilliard PHASE-FIELD diblock copolymer melts Ohta–Kawasaki model numerical methods pattern formation
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Dynamic Rockfall Hazard Assessment at Railway Tunnel Portal:Application of G1-FCE Method and 3D Numerical Simulation
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作者 Shengwei Zhang Jiaxing Dong +2 位作者 Yanjun Shen Qingjun Zuo Junli Wan 《Journal of Earth Science》 2025年第3期1341-1347,共7页
0 INTRODUCTION In recent years,modern railways have been actively under construction in the complex mountainous area of Southwest China.However,rockfall poses a significant threat to both construction and operation ph... 0 INTRODUCTION In recent years,modern railways have been actively under construction in the complex mountainous area of Southwest China.However,rockfall poses a significant threat to both construction and operation phases of railway projects(Yan et al.,2023;Chen et al.,2022;Fanos and Pradhan,2018). 展开更多
关键词 complex mountainous area hazard assessment dynamic rockfall railway tunnel portal D numerical simulation construction G FCE method southwest china
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3D numerical manifold method for crack propagation in rock materials using a local tracking algorithm
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作者 Boyi Su Tao Xu +3 位作者 Genhua Shi Michael J.Heap Xianyang Yu Guanglei Zhou 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第6期3449-3463,共15页
The modeling of crack growth in three-dimensional(3D)space poses significant challenges in rock mechanics due to the complex numerical computation involved in simulating crack propagation and interaction in rock mater... The modeling of crack growth in three-dimensional(3D)space poses significant challenges in rock mechanics due to the complex numerical computation involved in simulating crack propagation and interaction in rock materials.In this study,we present a novel approach that introduces a 3D numerical manifold method(3D-NMM)with a geometric kernel to enhance computational efficiency.Specifically,the maximum tensile stress criterion is adopted as a crack growth criterion to achieve strong discontinuous crack growth,and a local crack tracking algorithm and an angle correction technique are incorporated to address minor limitations of the algorithm in a 3D model.The implementation of the program is carried out in Python,using object-oriented programming in two independent modules:a calculation module and a crack module.Furthermore,we propose feasible improvements to enhance the performance of the algorithm.Finally,we demonstrate the feasibility and effectiveness of the enhanced algorithm in the 3D-NMM using four numerical examples.This study establishes the potential of the 3DNMM,combined with the local tracking algorithm,for accurately modeling 3D crack propagation in brittle rock materials. 展开更多
关键词 3D numerical manifold method(3D NMM) Crack propagation Local tracking algorithm Brittle materials
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Mobility and dynamic erosion process of granular flow:insights from numerical investigation using material point method 被引量:2
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作者 YU Fangwei SU Lijun +1 位作者 LI Xinpo ZHAO Yu 《Journal of Mountain Science》 SCIE CSCD 2024年第8期2713-2738,共26页
In order to understand the dynamics of granular flow on an erodible base soil,in this paper,a series of material point method-based granular column collapse tests were conducted to investigate numerically the mobility... In order to understand the dynamics of granular flow on an erodible base soil,in this paper,a series of material point method-based granular column collapse tests were conducted to investigate numerically the mobility and dynamic erosion process of granular flow subjected to the complex settings,i.e.,the aspect ratio,granular mass,friction and dilatancy resistance,gravity and presence of water.A set of power scaling laws were proposed to describe the final deposit characteristics of granular flow by the relations of the normalized run-out distance and the normalized final height of granular flow against the aspect ratio,being greatly affected by the complex geological settings,e.g.,granular mass,the friction and dilatancy resistance of granular soil,and presence of water in granular flow.An index of the coefficient of friction of granular soil was defined as a ratio of the target coefficient of friction over the initial coefficient of friction to quantify the scaling extent of friction change(i.e.,friction strengthening or weakening).There is a characteristic aspect ratio of granular column corresponding to the maximum mobility of granular flow with the minimum index of the apparent coefficient of friction.The index of the repose coefficient of friction of granular flow decreased gradually with the increase in aspect ratio because higher potential energy of granular column at a larger aspect ratio causes a larger kinetic energy of granular soil to weaken the friction of granular soil as a kind of velocity-related friction weakening.An increase in granular mass reduces gradually the indexes of the apparent and repose coefficients of friction of granular soil to enhance the mobility of granular flow.The mobility of granular flow increases gradually with the decrease in friction angle or increase in dilatancy angle of granular soil.However,the increase of gravity accelerates granular flow but showing the same final deposit profile without any dependence on gravity.The mobility of granular flow increases gradually by lowering the indexes of the apparent and repose coefficients of friction of granular flow while changing the surroundings,in turn,the dry soil,submerged soil and saturated soil,implying a gradually increased excessive mobility of granular flow with the friction weakening of granular soil.Presence of water in granular flow may be a potential catalyzer to yield a long run-out granular flow,as revealed in comparison of water-absent and water-present granular flows.In addition,the dynamic erosion and entrainment of based soil induced by granular flow subjected to the complex geological settings,i.e.,the aspect ratio,granular mass,gravity,friction and dilatancy resistance,and presence of water,were comprehensively investigated as well. 展开更多
关键词 Column collapse Granular flow Granular soil Material point method MOBILITY numerical tests
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Numerical manifold method for thermo-mechanical coupling simulation of fractured rock mass 被引量:2
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作者 Jiawei Liang Defu Tong +3 位作者 Fei Tan Xiongwei Yi Junpeng Zou Jiahe Lv 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第6期1977-1992,共16页
As a calculation method based on the Galerkin variation,the numerical manifold method(NMM)adopts a double covering system,which can easily deal with discontinuous deformation problems and has a high calculation accura... As a calculation method based on the Galerkin variation,the numerical manifold method(NMM)adopts a double covering system,which can easily deal with discontinuous deformation problems and has a high calculation accuracy.Aiming at the thermo-mechanical(TM)coupling problem of fractured rock masses,this study uses the NMM to simulate the processes of crack initiation and propagation in a rock mass under the influence of temperature field,deduces related system equations,and proposes a penalty function method to deal with boundary conditions.Numerical examples are employed to confirm the effectiveness and high accuracy of this method.By the thermal stress analysis of a thick-walled cylinder(TWC),the simulation of cracking in the TWC under heating and cooling conditions,and the simulation of thermal cracking of the SwedishÄspöPillar Stability Experiment(APSE)rock column,the thermal stress,and TM coupling are obtained.The numerical simulation results are in good agreement with the test data and other numerical results,thus verifying the effectiveness of the NMM in dealing with thermal stress and crack propagation problems of fractured rock masses. 展开更多
关键词 Heat conduction Fractured rock mass Crack propagation Galerkin variation numerical manifold method(NMM)
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A review of multiscale numerical modeling of rock mechanics and rock engineering
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作者 Xindong Wei Zhe Li Gaofeng Zhao 《Deep Underground Science and Engineering》 2025年第3期382-405,共24页
Rock is geometrically and mechanically multiscale in nature,and the traditional phenomenological laws at the macroscale cannot render a quantitative relationship between microscopic damage of rocks and overall rock st... Rock is geometrically and mechanically multiscale in nature,and the traditional phenomenological laws at the macroscale cannot render a quantitative relationship between microscopic damage of rocks and overall rock structural degradation.This may lead to problems in the evaluation of rock structure stability and safe life.Multiscale numerical modeling is regarded as an effective way to gain insight into factors affecting rock properties from a cross-scale view.This study compiles the history of theoretical developments and numerical techniques related to rock multiscale issues according to different modeling architectures,that is,the homogenization theory,the hierarchical approach,and the concurrent approach.For these approaches,their benefits,drawbacks,and application scope are underlined.Despite the considerable attempts that have been made,some key issues still result in multiple challenges.Therefore,this study points out the perspectives of rock multiscale issues so as to provide a research direction for the future.The review results show that,in addition to numerical techniques,for example,high-performance computing,more attention should be paid to the development of an advanced constitutive model with consideration of fine geometrical descriptions of rock to facilitate solutions to multiscale problems in rock mechanics and rock engineering. 展开更多
关键词 constitutive model multiscale modeling numerical method ROCK
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Numerically and Experimentally Establishing Rheology Law for AISI 1045 Steel Based on Uniaxial Hot Compression Tests
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作者 Josef Walek Petr Lichy 《Computer Modeling in Engineering & Sciences》 2025年第3期3135-3153,共19页
Plastometric experiments,supplemented with numerical simulations using the finite element method(FEM),can be advantageously used to characterize the deformation behavior of metallic materials.The accuracy of such simu... Plastometric experiments,supplemented with numerical simulations using the finite element method(FEM),can be advantageously used to characterize the deformation behavior of metallic materials.The accuracy of such simulations predicting deformation behaviors of materials is,however,primarily affected by the applied rheology law.The presented study focuses on the characterization of the deformation behavior of AISI 1045 type carbon steel,widely used e.g.,in automotive and power engineering,under extreme conditions(i.e.,high temperatures,strain rates).The study consists of two main parts:experimentally analyzing the flow stress development of the steel under different thermomechanical conditions via uniaxial hot compression tests and establishing the rheology law via numerical simulations implementing the experimentally acquired flow stress curves.The numerical simulations then not only serve to establish the rheology law but also to verify the reliability of the selected experimental process.The results of the numerical simulations showed that the established rheology law characterizes the behavior of the investigated steel with sufficient accuracy also at high temperatures and/or strain rates,and can,therefore,be used for practical purposes.Last but not least,supplementary microstructure analyses performed for the samples subjected to the highest deformation temperature provided a deeper insight into the effects of the applied(extreme)thermomechanical conditions on the behavior of the investigated steel. 展开更多
关键词 Rheology law numerical simulation finite element method hot compression test deformation behavior microstructure
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Numerical Simulation of Gas-Water Two-Phase Flow in a Proppant-Filled Layer
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作者 Jian Yang Xinghao Gou +4 位作者 Jiayi Sun Fei Liu Xiaojin Zhou Xu Liu Tao Zhang 《Fluid Dynamics & Materials Processing》 2025年第8期1935-1954,共20页
Shale gas production involves complex gas-water two-phase flow,with flow patterns in proppant-filled fractures playing a critical role in determining production efficiency.In this study,3D geometric models of 40/70 me... Shale gas production involves complex gas-water two-phase flow,with flow patterns in proppant-filled fractures playing a critical role in determining production efficiency.In this study,3D geometric models of 40/70 mesh ceramic particles and quartz sand proppant clusters were elaborated using computed tomography(CT)scanning.These models were used to develop a numerical simulation framework based on the lattice Boltzmann method(LBM),enabling the investigation of gas-water flow behavior within proppant-filled fractures under varying driving forces and surface tensions.Simulation results at a closure pressure of 15 MPa have revealed that ceramic particles exhibit a simpler and more porous internal structure than quartz sand of the same size.Under identical flow conditions,ceramic proppants demonstrate higher fluid replacement efficiency.Replacement efficiency increases with higher porosity,greater driving force,and lower surface tension.Furthermore,fluid displacement is strongly influenced by pore geometry:flow is faster in straighter and wider channels,with preferential movement through larger pores forming dominant flow paths.The replacement velocity exhibits a characteristic time evolution,initially rapid,then gradually decreasing,correlating positively with the development of these dominant channels. 展开更多
关键词 Proppant fractures gas-water two-phase flow numerical simulation lattice Boltzmann method flow behavior
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Numerical investigation on a comprehensive high-order finite particle scheme
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作者 Yudong LI Yan LI +2 位作者 Chunfa WANG PJOLI Zhiqiang FENG 《Applied Mathematics and Mechanics(English Edition)》 2025年第6期1187-1214,共28页
In the field of discretization-based meshfree/meshless methods,the improvements in the higher-order consistency,stability,and computational efficiency are of great concerns in computational science and numerical solut... In the field of discretization-based meshfree/meshless methods,the improvements in the higher-order consistency,stability,and computational efficiency are of great concerns in computational science and numerical solutions to partial differential equations.Various alternative numerical methods of the finite particle method(FPM)frame have been extended from mathematical theories to numerical applications separately.As a comprehensive numerical scheme,this study suggests a unified resolved program for numerically investigating their accuracy,stability,consistency,computational efficiency,and practical applicability in industrial engineering contexts.The high-order finite particle method(HFPM)and corrected methods based on the multivariate Taylor series expansion are constructed and analyzed to investigate the whole applicability in different benchmarks of computational fluid dynamics.Specifically,four benchmarks are designed purposefully from statical exact solutions to multifaceted hydrodynamic tests,which possess different numerical performances on the particle consistency,numerical discretized forms,particle distributions,and transient time evolutional stabilities.This study offers a numerical reference for the current unified resolved program. 展开更多
关键词 numerical method high-order finite particle method(HFPM) kernel gradient correction(KGC) decoupled finite particle method(DFPM) weakly compressible smoothed particle hydrodynamics(SPH)
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4D Grid-fitting of UV-optical Spectra of Massive Stars.I.Numerical Technique and its Associated Uncertainties
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作者 Blagovest V.Petrov Svetozar A.Zhekov 《Research in Astronomy and Astrophysics》 2025年第7期111-131,共21页
The best way to check the validity of our theories(models)is by direct comparison with the experiment(observations).However,this process suffers from numerical inaccuracies,which are not frequently studied and often r... The best way to check the validity of our theories(models)is by direct comparison with the experiment(observations).However,this process suffers from numerical inaccuracies,which are not frequently studied and often remain mostly unknown.In this study,we focus on addressing the numerical inaccuracies intrinsic to the process of comparing theory and observations.To achieve this goal,we built four-dimensional(4D)spectral grids for Wolf–Rayet stars(WC and WN spectral classes)and blue supergiants characterized by low metallicity similar to that of the Small Magellanic Cloud.In contrast to lighter(three-dimensional)grids,which rely on a priori assumptions about certain stellar parameters(e.g.,wind velocity)and thus have limited applicability,our 4D grids vary four independent parameters,enabling more flexible and broadly applicable spectral fitting.Utilizing these 4D grids,we developed and validated a fitting approach facilitating direct fits to observed spectra.Through rigorous testing on designated“test”models,we demonstrated that the numerical precision of derived essential stellar parameters,including effective temperature,mass-loss rate,luminosity,and wind velocity,is better than 0.05 dex.Furthermore,we explored the influence of unaccounted factors,including variations in the metal abundances,wind acceleration laws,and clumping,on the precision of the derived parameters.The results indicate that the first two factors have the strongest influence on the numerical accuracy of the derived stellar parameters.Variations in abundances predominantly influenced the mass-loss rate for weak-wind scenarios,while effective temperature and luminosity remained robust.We found that the wind acceleration law influences the numerical uncertainty of the derived wind parameters mostly for models with weak winds.Interestingly,different degrees of clumping demonstrated good precision for spectra with strong winds,contrasting with a decrease in the precision for weak-wind cases.We found also that the accuracy of our approach depends on spectral range and the inclusion of ultraviolet spectral range improves the precision of derived parameters,especially for an object with weak winds. 展开更多
关键词 stars:Wolf-Rayet stars:winds outfows methods:numerical stars:massive
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Impact dynamics of granular flow on rigid barriers:insights from numerical investigation using material point method
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作者 YU Fangwei SU Lijun +1 位作者 LI Xinpo ZHAO Yu 《Journal of Mountain Science》 SCIE CSCD 2024年第12期4083-4111,共29页
In order to advance the understanding of the impact dynamics of granular flow in complex geological settings,this paper studied the impact dynamics of granular flow on rigid barriers with a number of Material Point Me... In order to advance the understanding of the impact dynamics of granular flow in complex geological settings,this paper studied the impact dynamics of granular flow on rigid barriers with a number of Material Point Method(MPM)numerical tests.The impact behavior of granular flow on a rigid barrier was characterized by the initial dynamic impact stage,dynamic surge impact stage,compression impact stage and static stage of granular flow,where the impact force of granular flow was comprised of the dynamic and static forces of granular flow.The impact behavior of granular flow on a rigid barrier was characterized by the states of the fast or slow impact behavior of granular flow.The angle of slope and aspect ratio of granular soil greatly affected the impact behavior of granular flow on a column rigid barrier,where a power model was proposed to quantify the residual(Fnr)-over-maximum(Fnmax)normal impact force ratio of granular flow Fnr⁄Fnmax incorporating the effects of the angle of slope and aspect ratio of granular soil.With the increase of the column rigid barrier up to the semi-infinite column rigid barrier,the impact dynamics of granular flow gradually increased up to a maximum by progressively transforming the overflow into the dynamic surge impact of the incoming flow on the rigid barrier to capture more granular soil of granular flow against the rigid barrier.Presence of water in granular flow,i.e.,a mixture of solid and liquid in granular flow,yielded a dynamic coupling contribution of the solid and liquid,being accompanied by the whole dynamic process of granular flow,on the impact behavior of granular flow on a rigid barrier,where the liquid-phase material of granular flow,i.e.,the water,was predominant to contribute on the normal impact force of granular flow in comparison with the solid-phase material of granular flow.In addition,other factors,e.g.,the shape of rigid barrier(i.e.,the column barrier,arch barrier and circle barrier),and the gravity(i.e.,in the gravitational environment of the Moon,Earth and Mars),greatly affected the impact behavior of granular flow on a rigid barrier as well. 展开更多
关键词 Column collapse Granular flow Impact force Material point method numerical tests Rigid barrier
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Numerical simulation study on the mold strength of magnetic mold casting based on a coupled electromagnetic-structural method
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作者 Wei-li Peng Jian-hua Zhao +1 位作者 Cheng Gu Ya-jun Wang 《China Foundry》 SCIE EI CAS CSCD 2024年第5期577-587,共11页
The properties of the magnetic mold in magnetic mold casting directly determine the quality of the final cast parts.In this study,the magnetic mold properties in magnetic mold casting,were studied utilizing a coupled ... The properties of the magnetic mold in magnetic mold casting directly determine the quality of the final cast parts.In this study,the magnetic mold properties in magnetic mold casting,were studied utilizing a coupled electromagnetic-structural method through numerical simulation.This study investigated key factors including equivalent stress,the distribution of tensile and compressive stresses,and the area ratio of tensile stress.It compared molds made entirely of magnetic materials with those made partially of magnetic materials.Simulation results indicate that as current increases from 4 A to 8 A,both the initial magnetic mold and the material-replaced magnetic mold initially show an increasing trend in equivalent stress,tensile-compressive stress,and the area ratio of tensile stress,peaking at 6 A before declining.After material replacement,the area ratio of tensile stress at 6 A decreases to 19.84%,representing a reduction of 29.72%.Magnetic molds comprising a combination of magnetic and non-magnetic materials exhibit sufficient strength and a reduced area ratio of tensile stress compared to those made entirely from magnetic materials.This study provides valuable insights for optimizing magnetic mold casting processes and offers practical guidance for advancing the application of magnetic molds. 展开更多
关键词 magnetic mold casting coupled electromagnetic-structural method numerical simulation stress analysis
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Numerical Simulation of Oil-Water Two-Phase Flow in Low Permeability Tight Reservoirs Based on Weighted Least Squares Meshless Method
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作者 Xin Liu Kai Yan +3 位作者 Bo Fang Xiaoyu Sun Daqiang Feng Li Yin 《Fluid Dynamics & Materials Processing》 EI 2024年第7期1539-1552,共14页
In response to the complex characteristics of actual low-permeability tight reservoirs,this study develops a meshless-based numerical simulation method for oil-water two-phase flow in these reservoirs,considering comp... In response to the complex characteristics of actual low-permeability tight reservoirs,this study develops a meshless-based numerical simulation method for oil-water two-phase flow in these reservoirs,considering complex boundary shapes.Utilizing radial basis function point interpolation,the method approximates shape functions for unknown functions within the nodal influence domain.The shape functions constructed by the aforementioned meshless interpolation method haveδ-function properties,which facilitate the handling of essential aspects like the controlled bottom-hole flow pressure in horizontal wells.Moreover,the meshless method offers greater flexibility and freedom compared to grid cell discretization,making it simpler to discretize complex geometries.A variational principle for the flow control equation group is introduced using a weighted least squares meshless method,and the pressure distribution is solved implicitly.Example results demonstrate that the computational outcomes of the meshless point cloud model,which has a relatively small degree of freedom,are in close agreement with those of the Discrete Fracture Model(DFM)employing refined grid partitioning,with pressure calculation accuracy exceeding 98.2%.Compared to high-resolution grid-based computational methods,the meshless method can achieve a better balance between computational efficiency and accuracy.Additionally,the impact of fracture half-length on the productivity of horizontal wells is discussed.The results indicate that increasing the fracture half-length is an effective strategy for enhancing production from the perspective of cumulative oil production. 展开更多
关键词 Weighted least squares method meshless method numerical simulation of low permeability tight reservoirs oil-water two-phase flow fracture half-length
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