This study presents an effective hybrid simulation approach for simulating broadband ground motion in complex near-fault locations.The approach utilizes a deterministic approach based on the spectral element method(SE...This study presents an effective hybrid simulation approach for simulating broadband ground motion in complex near-fault locations.The approach utilizes a deterministic approach based on the spectral element method(SEM),which is used to simulate low-frequency ground motion(f<1 Hz)by incorporating an innovative efficient discontinuous Galerkin(DG)method for grid division to accurately model basin sedimentary layers at reduced costs.It also introduces a comprehensive hybrid source model for high-frequency random scattering and a nonlinear analysis module for basin sedimentary layers.Deterministic outcomes are combined with modified three-dimensional stochastic finite fault method(3D-EXSIM)simulations of high-frequency ground motion(f>1 Hz).A fourth-order Butterworth filter with zero phase shift is employed for time-domain filtering of low-and high-frequency time series at a crossover frequency of 1 Hz,merging the low and high-frequency ground motions into a broadband time series.Taking an Ms 6.8 Luding earthquake,as an example,this hybrid method was used for a rapid and efficient simulation analysis of broadband ground motion in the region.The accuracy and efficiency of this hybrid method were verified through comparisons with actually observed station data and empirical attenuation curves.Deterministic method simulation results revealed the effects of mountainous topography,basin effects,nonlinear effects within the basin’s sedimentary layers,and a coupling interaction between the basin and the mountains.The findings are consistent with similar studies,showing that near-fault sedimentary basins significantly focus and amplify strong ground motion,and the soil’s nonlinear behavior in the basin influences ground motion to varying extents at different distances from the fault.The mountainous topography impacts the basin’s response to ground motion,leading to barrier effects.This research provides a scientific foundation for seismic zoning,urban planning,and seismic design in nearfault mountain basin regions.展开更多
Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The t...Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.展开更多
Shock wave caused by a sudden release of high-energy,such as explosion and blast,usually affects a significant range of areas.The utilization of a uniform fine mesh to capture sharp shock wave and to obtain precise re...Shock wave caused by a sudden release of high-energy,such as explosion and blast,usually affects a significant range of areas.The utilization of a uniform fine mesh to capture sharp shock wave and to obtain precise results is inefficient in terms of computational resource.This is particularly evident when large-scale fluid field simulations are conducted with significant differences in computational domain size.In this work,a variable-domain-size adaptive mesh enlargement(vAME)method is developed based on the proposed adaptive mesh enlargement(AME)method for modeling multi-explosives explosion problems.The vAME method reduces the division of numerous empty areas or unnecessary computational domains by adaptively suspending enlargement operation in one or two directions,rather than in all directions as in AME method.A series of numerical tests via AME and vAME with varying nonintegral enlargement ratios and different mesh numbers are simulated to verify the efficiency and order of accuracy.An estimate of speedup ratio is analyzed for further efficiency comparison.Several large-scale near-ground explosion experiments with single/multiple explosives are performed to analyze the shock wave superposition formed by the incident wave,reflected wave,and Mach wave.Additionally,the vAME method is employed to validate the accuracy,as well as to investigate the performance of the fluid field and shock wave propagation,considering explosive quantities ranging from 1 to 5 while maintaining a constant total mass.The results show a satisfactory correlation between the overpressure versus time curves for experiments and numerical simulations.The vAME method yields a competitive efficiency,increasing the computational speed to 3.0 and approximately 120,000 times in comparison to AME and the fully fine mesh method,respectively.It indicates that the vAME method reduces the computational cost with minimal impact on the results for such large-scale high-energy release problems with significant differences in computational domain size.展开更多
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
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
At low-Reynolds-number,the performance of airfoil is known to be greatly affected by the formation and burst of a laminar separation bubble(LSB),which requires a more precise simulation of the delicate flow structures...At low-Reynolds-number,the performance of airfoil is known to be greatly affected by the formation and burst of a laminar separation bubble(LSB),which requires a more precise simulation of the delicate flow structures.A framework based on the interior penalty discontinuous Galerkin method and large eddy simulation approach was adopted in the present study.The performances of various subgrid models,including the Smagorinsky(SM)model,the dynamic Smagorinsky(DSM)model,the wall-adapting local-eddy-viscosity(WALE)model,and the VREMAN model,have been analyzed through flow simulations of the SD7003 airfoil at a Reynolds number of 60000.It turns out that the SM model fails to predict the emergence of LSB,even modified by the Van-Driest damping function.On the contrary,the best agreement is generally achieved by the WALE model in terms of flow separation,reattachment,and transition locations,together with the aerodynamic loads.Furthermore,the influence of numerical dissipation has also been discussed through the comparison of skin friction and resolved Reynolds stresses.As numerical dissipation decreases,the prediction accuracy of the WALE model degrades.Meanwhile,nonlinear variation could be observed from the performances of the DSM model,which could be attributed to the interaction between the numerical dissipation and the subgrid model.展开更多
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
The high-speed winding spindle employs a flexible support system incorporating rubber O-rings.By precisely configuring the structural parameters and the number of the O-rings,the spindle can stably surpass its critica...The high-speed winding spindle employs a flexible support system incorporating rubber O-rings.By precisely configuring the structural parameters and the number of the O-rings,the spindle can stably surpass its critical speed points and maintain operational stability across the entire working speed range.However,the support stiffness and damping of rubber O-rings exhibit significant nonlinear frequency dependence.Conventional experimental methods for deriving equivalent stiffness and damping,based on the principle of the forced non-resonance method,require fabricating custom setups for each O-ring specification and conducting vibration tests at varying frequencies,resulting in low efficiency and high costs.This study proposes a hybrid simulation-experimental method for dynamic parameter identification.Firstly,the frequency-dependent dynamic parameters of a specific O-ring support system are experimentally obtained.Subsequently,a corresponding parametric finite element model is established to simulate and solve the equivalent elastic modulus and equivalent stiffness-damping coefficient of this O-ring support system.Ultimately,after iterative simulation,the simulated and experimental results achieve a 99.7%agreement.The parametric finite element model developed herein can directly simulate and inversely estimate frequency-dependent dynamic parameters for O-rings of different specifications but identical elastic modulus.展开更多
The March 28,2025 Myanmar earthquake generated ground shaking that was perceptible throughout Myanmar and adjacent regions.This study simulated three-component ground motions across the affected region using an improv...The March 28,2025 Myanmar earthquake generated ground shaking that was perceptible throughout Myanmar and adjacent regions.This study simulated three-component ground motions across the affected region using an improved stochastic finite-fault method to systematically assess seismic impacts.Observed near-field recordings at MM.NGU station was used to determine the reliability of the theoretically derived stress drop as input for simulation.Far-field recordings constrained the frequency-dependent S-wave quality factors(Q(f)=283.305f^(0.588))for anelastic attenuation modeling.Comparisons of peak accelerations between simulation and empirical ground-motion models showed good agreement at moderate-to-large distances.However,lower near-fault simulations indicate a weaker-than-average source effect.Analysis of simulated instrumental seismic intensity revealed key patterns.Maximum intensity(Ⅹ)occurred in isolated patches within the ruptured fault projection,correlating with shallow high-slip areas.TheⅨ-intensity zone formed a north-south elongated band centered on fault projection.Significant asymmetry inⅧ-intensity distribution perpendicular to the fault strike was observed,with a wider western extension attributed to lower shear-wave velocities west of the fault.Supershear rupture behavior enhanced ground motions,expanding intensity ranges by~20%compared to sub-shear rupture.This study reveals the integrated effects of fault geometry,slip spatial distribution,rupture velocity,and site condition in governing ground motion patterns.展开更多
In this study,a homogenization method is employed to determine the values of effective elastic modulus for BaZrO3 which is a promising candidate material for electrolyte in solid oxide fuel cell (SOFC).Comparison betw...In this study,a homogenization method is employed to determine the values of effective elastic modulus for BaZrO3 which is a promising candidate material for electrolyte in solid oxide fuel cell (SOFC).Comparison between the homogenization and the analysis data reveals that the difference becomes significant with increasing of porosity when upper 20%.The empire mechanic behavior in a typical planar fuel cell is evaluated using finite element method (FEM).Large stress gradient occurs in vicinity of the interface of the electrolyte and the cathode due to theirs mismatch of thermal expansion coefficient (TEC).Moreover,local processing results reveal that microscopic stress concentration around pore near the interface of the electrolyte and the cathode in the cell perhaps produces cracks which may lead to the fail of the electrolyte and the lower energy convention efficiency.展开更多
To analyze the spring disturbance torque caused by motionai cable harness in a stabilized platform, the Kirchhoff theory based cable harness model has been previously developed to dynamically simulate the motional cab...To analyze the spring disturbance torque caused by motionai cable harness in a stabilized platform, the Kirchhoff theory based cable harness model has been previously developed to dynamically simulate the motional cable harness. In this paper, this model was validated by comparing the simulation results with the experiment results （ both the spring force and the deformed profile of the motional cable harness）. In the experiment, a special optical measuring instrument based on binocular vision was developed and the motion and deformation of cable harness were measured. A simpli- fied stabilized platform system was constructed, and the absolute value of spring disturbance force during the motion of this simplified frame was obtained by using a force gauge （0. 02 N precision）. The physical parameters of experimental specimen were also measured. The experimental and simulated results showed good agreement. These results should be useful for better motional cable harness layout design and reliable evaluation of the spring disturbance torque.展开更多
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
1.Introduction Computational Fluid Dynamics-Discrete Element Method(CFD-DEM)is a powerful tool for simulating dense gas-solid reacting flows,which is essential in combustion,metallurgy,and waste management.Traditional...1.Introduction Computational Fluid Dynamics-Discrete Element Method(CFD-DEM)is a powerful tool for simulating dense gas-solid reacting flows,which is essential in combustion,metallurgy,and waste management.Traditional methods face challenges in CFD-DEM modeling of dense gas-solid flows due to multi-scale characteristics,limiting resolution and creating simulation bottlenecks.By integrating fluid dynamics and particle behavior,it optimizes industrial processes.This review highlights advancements,applications,and challenges,emphasizing its role in sustainable engineering.展开更多
In this paper two classes of equivalence transform methods for solving ordinary differential equations are proposed. One class of method is the equivalence integral transform method for special differential algebraic ...In this paper two classes of equivalence transform methods for solving ordinary differential equations are proposed. One class of method is the equivalence integral transform method for special differential algebraic problems. The advantage of this class of method is such that the amount of work calculating one integration with parameters becomes that of two interpolations, when the system of nonlinear equations is solved on the right hand side function. The other class of method is the equivalence substitution method for avoiding calculating derivative on the right hand side function. In order to avoid calculation derivatives, two equivalence substitution methods are proposed here. The application instances of some special effect of the equivalence substitution methods are given.展开更多
The following article has been retracted due to the investigation of complaints received against it. Mr. Mohammadali Ghorbani (corresponding author and also the last author) cheated the author’s name: Alireza Heidari...The following article has been retracted due to the investigation of complaints received against it. Mr. Mohammadali Ghorbani (corresponding author and also the last author) cheated the author’s name: Alireza Heidari. The scientific community takes a very strong view on this matter and we treat all unethical behavior such as plagiarism seriously. This paper published in Vol.3 No.3, 260-265, 2012, has been removed from this site.展开更多
We propose a symplectic partitioned Runge-Kutta （SPRK） method with eighth-order spatial accuracy based on the extended Hamiltonian system of the acoustic waveequation. Known as the eighth-order NSPRK method, this te...We propose a symplectic partitioned Runge-Kutta （SPRK） method with eighth-order spatial accuracy based on the extended Hamiltonian system of the acoustic waveequation. Known as the eighth-order NSPRK method, this technique uses an eighth-orderaccurate nearly analytic discrete （NAD） operator to discretize high-order spatial differentialoperators and employs a second-order SPRK method to discretize temporal derivatives.The stability criteria and numerical dispersion relations of the eighth-order NSPRK methodare given by a semi-analytical method and are tested by numerical experiments. We alsoshow the differences of the numerical dispersions between the eighth-order NSPRK methodand conventional numerical methods such as the fourth-order NSPRK method, the eighth-order Lax-Wendroff correction （LWC） method and the eighth-order staggered-grid （SG）method. The result shows that the ability of the eighth-order NSPRK method to suppress thenumerical dispersion is obviously superior to that of the conventional numerical methods. Inthe same computational environment, to eliminate visible numerical dispersions, the eighth-order NSPRK is approximately 2.5 times faster than the fourth-order NSPRK and 3.4 timesfaster than the fourth-order SPRK, and the memory requirement is only approximately47.17% of the fourth-order NSPRK method and 49.41% of the fourth-order SPRK method,which indicates the highest computational efficiency. Modeling examples for the two-layermodels such as the heterogeneous and Marmousi models show that the wavefields generatedby the eighth-order NSPRK method are very clear with no visible numerical dispersion.These numerical experiments illustrate that the eighth-order NSPRK method can effectivelysuppress numerical dispersion when coarse grids are adopted. Therefore, this methodcan greatly decrease computer memory requirement and accelerate the forward modelingproductivity. In general, the eighth-order NSPRK method has tremendous potential value forseismic exploration and seismology research.展开更多
The influence of supercooled melt forced lamina flow on microsegregation was investigated. The concentration distribution at solid-liquid boundary of binary alloy Ni-Cu was simulated using phase field model coupled wi...The influence of supercooled melt forced lamina flow on microsegregation was investigated. The concentration distribution at solid-liquid boundary of binary alloy Ni-Cu was simulated using phase field model coupled with flow field. The microsegregation, concentration maximum value, boundary thickness of concentration near upstream dendrite and normal to flow dendrite, and downstream dendrite were studied quantitatively in the case of forced lamia flow. The simulation results show that solute field and flow field interact complexly. Compared with melt without flow, in front of upstream dendrite tip, the concentration boundary thickness is the lowest and the concentration maximum value is the smallest for melt with flow. However, in front of downstream dendrite tip, the results are just the opposite. The zone of poor Cu in upstream dendrite where is the most severely microsegregation and shrinkage cavity is wider and the concentration is lower for melt with flow than that without flow.展开更多
In order to predict the long-term rutting of asphalt pavement, the effective temperature for pavement rutting is calculated using the numerical simulation method. The transient temperature field of asphalt pavement wa...In order to predict the long-term rutting of asphalt pavement, the effective temperature for pavement rutting is calculated using the numerical simulation method. The transient temperature field of asphalt pavement was simulated based on actual meteorological data of Nanjing. 24-hour rutting development under a transient temperature field was calculated in each month. The rutting depth accumulated under the static temperature field was also estimated and the relationship between constant temperature parameters was analyzed. Then the effective temperature for pavement rutting was determined based on the rutting equivalence principle. The results show that the monthly effective temperature is above 40 t in July and August, while in June and September it ranges from 30 to 40 Rutting development can be ignored when the monthly effective temperature is less than 30 t. The yearly effective temperature for rutting in Nanjing is around 38. 5 t. The long-term rutting prediction model based on the effective temperature can reflect the influences of meteorological factors and traffic time distribution.展开更多
LS-DYNA program and the principle of ALE method were introduced, and the target features of the reinforced concrete penetration were analyzed by using the D material model and the ALE method. A numerical simulation ha...LS-DYNA program and the principle of ALE method were introduced, and the target features of the reinforced concrete penetration were analyzed by using the D material model and the ALE method. A numerical simulation has been done to show the penetration visually and veritably. The simulation results are analyzed carefully and explicitly prove their significance to the research of reinforced concrete penetration.展开更多
基金National Natural Science Foundation of China under Grant Nos.U2139208 and 52278516Key Laboratory of Earthquake Engineering and Engineering Vibration,China Earthquake Administration under Grant No.2024D15Key Laboratory of Soft Soil Characteristic and Engineering Environment,Tianjin Chengjian University under Grant No.2022SCEEKL003。
文摘This study presents an effective hybrid simulation approach for simulating broadband ground motion in complex near-fault locations.The approach utilizes a deterministic approach based on the spectral element method(SEM),which is used to simulate low-frequency ground motion(f<1 Hz)by incorporating an innovative efficient discontinuous Galerkin(DG)method for grid division to accurately model basin sedimentary layers at reduced costs.It also introduces a comprehensive hybrid source model for high-frequency random scattering and a nonlinear analysis module for basin sedimentary layers.Deterministic outcomes are combined with modified three-dimensional stochastic finite fault method(3D-EXSIM)simulations of high-frequency ground motion(f>1 Hz).A fourth-order Butterworth filter with zero phase shift is employed for time-domain filtering of low-and high-frequency time series at a crossover frequency of 1 Hz,merging the low and high-frequency ground motions into a broadband time series.Taking an Ms 6.8 Luding earthquake,as an example,this hybrid method was used for a rapid and efficient simulation analysis of broadband ground motion in the region.The accuracy and efficiency of this hybrid method were verified through comparisons with actually observed station data and empirical attenuation curves.Deterministic method simulation results revealed the effects of mountainous topography,basin effects,nonlinear effects within the basin’s sedimentary layers,and a coupling interaction between the basin and the mountains.The findings are consistent with similar studies,showing that near-fault sedimentary basins significantly focus and amplify strong ground motion,and the soil’s nonlinear behavior in the basin influences ground motion to varying extents at different distances from the fault.The mountainous topography impacts the basin’s response to ground motion,leading to barrier effects.This research provides a scientific foundation for seismic zoning,urban planning,and seismic design in nearfault mountain basin regions.
基金Supported by the National Natural Science Foundation of China under Grant No.51975138the High-Tech Ship Scientific Research Project from the Ministry of Industry and Information Technology under Grant No.CJ05N20the National Defense Basic Research Project under Grant No.JCKY2023604C006.
文摘Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.
基金supported by the National Natural Science Foundation of China(Grant Nos.12302435 and 12221002)。
文摘Shock wave caused by a sudden release of high-energy,such as explosion and blast,usually affects a significant range of areas.The utilization of a uniform fine mesh to capture sharp shock wave and to obtain precise results is inefficient in terms of computational resource.This is particularly evident when large-scale fluid field simulations are conducted with significant differences in computational domain size.In this work,a variable-domain-size adaptive mesh enlargement(vAME)method is developed based on the proposed adaptive mesh enlargement(AME)method for modeling multi-explosives explosion problems.The vAME method reduces the division of numerous empty areas or unnecessary computational domains by adaptively suspending enlargement operation in one or two directions,rather than in all directions as in AME method.A series of numerical tests via AME and vAME with varying nonintegral enlargement ratios and different mesh numbers are simulated to verify the efficiency and order of accuracy.An estimate of speedup ratio is analyzed for further efficiency comparison.Several large-scale near-ground explosion experiments with single/multiple explosives are performed to analyze the shock wave superposition formed by the incident wave,reflected wave,and Mach wave.Additionally,the vAME method is employed to validate the accuracy,as well as to investigate the performance of the fluid field and shock wave propagation,considering explosive quantities ranging from 1 to 5 while maintaining a constant total mass.The results show a satisfactory correlation between the overpressure versus time curves for experiments and numerical simulations.The vAME method yields a competitive efficiency,increasing the computational speed to 3.0 and approximately 120,000 times in comparison to AME and the fully fine mesh method,respectively.It indicates that the vAME method reduces the computational cost with minimal impact on the results for such large-scale high-energy release problems with significant differences in computational domain size.
基金supported by the National Key Research and Development Program of China(2022YFC2904400)Guangxi Science and Technology Major Project(Gui Ke AA23023033)。
文摘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.
基金funded by the 14th Five-Year Plan Major Science and Technology Project of CNOOC project number KJGG2021-0506.
文摘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.
基金This work was supported by the National Key R&D Program of China(Grant No.2022YFE0207000)the National Natural Science Foundation of China(Grant Nos.12372289,11972250,and 12102298)+1 种基金the China Postdoctoral Science Foundation(Grant No.2021M702443)Tianjin Natural Science Foundation(Grant No.22JCZDJC00910).
文摘At low-Reynolds-number,the performance of airfoil is known to be greatly affected by the formation and burst of a laminar separation bubble(LSB),which requires a more precise simulation of the delicate flow structures.A framework based on the interior penalty discontinuous Galerkin method and large eddy simulation approach was adopted in the present study.The performances of various subgrid models,including the Smagorinsky(SM)model,the dynamic Smagorinsky(DSM)model,the wall-adapting local-eddy-viscosity(WALE)model,and the VREMAN model,have been analyzed through flow simulations of the SD7003 airfoil at a Reynolds number of 60000.It turns out that the SM model fails to predict the emergence of LSB,even modified by the Van-Driest damping function.On the contrary,the best agreement is generally achieved by the WALE model in terms of flow separation,reattachment,and transition locations,together with the aerodynamic loads.Furthermore,the influence of numerical dissipation has also been discussed through the comparison of skin friction and resolved Reynolds stresses.As numerical dissipation decreases,the prediction accuracy of the WALE model degrades.Meanwhile,nonlinear variation could be observed from the performances of the DSM model,which could be attributed to the interaction between the numerical dissipation and the subgrid model.
基金the financial support from National Key R&D Program of China(Grant number:2024YFC2815100)Natural Science Foundation of China(Grant number:52322110)Beijing Nova Program(Grant number:20230484341).
文摘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.
基金National Key R&D Program of China(No.2017YFB1304000)Fundamental Research Funds for the Central Universities,China(No.2232023G-05-1)。
文摘The high-speed winding spindle employs a flexible support system incorporating rubber O-rings.By precisely configuring the structural parameters and the number of the O-rings,the spindle can stably surpass its critical speed points and maintain operational stability across the entire working speed range.However,the support stiffness and damping of rubber O-rings exhibit significant nonlinear frequency dependence.Conventional experimental methods for deriving equivalent stiffness and damping,based on the principle of the forced non-resonance method,require fabricating custom setups for each O-ring specification and conducting vibration tests at varying frequencies,resulting in low efficiency and high costs.This study proposes a hybrid simulation-experimental method for dynamic parameter identification.Firstly,the frequency-dependent dynamic parameters of a specific O-ring support system are experimentally obtained.Subsequently,a corresponding parametric finite element model is established to simulate and solve the equivalent elastic modulus and equivalent stiffness-damping coefficient of this O-ring support system.Ultimately,after iterative simulation,the simulated and experimental results achieve a 99.7%agreement.The parametric finite element model developed herein can directly simulate and inversely estimate frequency-dependent dynamic parameters for O-rings of different specifications but identical elastic modulus.
基金National Key R&D Program of China under Grant No.2022YFC3003601。
文摘The March 28,2025 Myanmar earthquake generated ground shaking that was perceptible throughout Myanmar and adjacent regions.This study simulated three-component ground motions across the affected region using an improved stochastic finite-fault method to systematically assess seismic impacts.Observed near-field recordings at MM.NGU station was used to determine the reliability of the theoretically derived stress drop as input for simulation.Far-field recordings constrained the frequency-dependent S-wave quality factors(Q(f)=283.305f^(0.588))for anelastic attenuation modeling.Comparisons of peak accelerations between simulation and empirical ground-motion models showed good agreement at moderate-to-large distances.However,lower near-fault simulations indicate a weaker-than-average source effect.Analysis of simulated instrumental seismic intensity revealed key patterns.Maximum intensity(Ⅹ)occurred in isolated patches within the ruptured fault projection,correlating with shallow high-slip areas.TheⅨ-intensity zone formed a north-south elongated band centered on fault projection.Significant asymmetry inⅧ-intensity distribution perpendicular to the fault strike was observed,with a wider western extension attributed to lower shear-wave velocities west of the fault.Supershear rupture behavior enhanced ground motions,expanding intensity ranges by~20%compared to sub-shear rupture.This study reveals the integrated effects of fault geometry,slip spatial distribution,rupture velocity,and site condition in governing ground motion patterns.
基金the support by the Medicine and Engineering Project
文摘In this study,a homogenization method is employed to determine the values of effective elastic modulus for BaZrO3 which is a promising candidate material for electrolyte in solid oxide fuel cell (SOFC).Comparison between the homogenization and the analysis data reveals that the difference becomes significant with increasing of porosity when upper 20%.The empire mechanic behavior in a typical planar fuel cell is evaluated using finite element method (FEM).Large stress gradient occurs in vicinity of the interface of the electrolyte and the cathode due to theirs mismatch of thermal expansion coefficient (TEC).Moreover,local processing results reveal that microscopic stress concentration around pore near the interface of the electrolyte and the cathode in the cell perhaps produces cracks which may lead to the fail of the electrolyte and the lower energy convention efficiency.
基金Supported by the National Natural Science Foundation of China(50805009)
文摘To analyze the spring disturbance torque caused by motionai cable harness in a stabilized platform, the Kirchhoff theory based cable harness model has been previously developed to dynamically simulate the motional cable harness. In this paper, this model was validated by comparing the simulation results with the experiment results （ both the spring force and the deformed profile of the motional cable harness）. In the experiment, a special optical measuring instrument based on binocular vision was developed and the motion and deformation of cable harness were measured. A simpli- fied stabilized platform system was constructed, and the absolute value of spring disturbance force during the motion of this simplified frame was obtained by using a force gauge （0. 02 N precision）. The physical parameters of experimental specimen were also measured. The experimental and simulated results showed good agreement. These results should be useful for better motional cable harness layout design and reliable evaluation of the spring disturbance torque.
基金supported by the Open Research Fund of Key Laboratory of Geological Hazards on Three Gorges Reservoir Area(China Three Gorges University),Ministry of Education(No.2022KDZ03)the Science and Technology Projects of Yunnan Provincial Science and Technology Department(No.202401AT070328)+1 种基金the Young talents project of“Xingdian Talent Support Program”in Yunnan Province(No.YNWR-QNBJ-2020-019)the Fund Project of China Academy of Railway Sciences Co.,Ltd.(No.2021YJ178)。
文摘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).
文摘1.Introduction Computational Fluid Dynamics-Discrete Element Method(CFD-DEM)is a powerful tool for simulating dense gas-solid reacting flows,which is essential in combustion,metallurgy,and waste management.Traditional methods face challenges in CFD-DEM modeling of dense gas-solid flows due to multi-scale characteristics,limiting resolution and creating simulation bottlenecks.By integrating fluid dynamics and particle behavior,it optimizes industrial processes.This review highlights advancements,applications,and challenges,emphasizing its role in sustainable engineering.
基金The project was supported by the National Natural Science Faundation of China
文摘In this paper two classes of equivalence transform methods for solving ordinary differential equations are proposed. One class of method is the equivalence integral transform method for special differential algebraic problems. The advantage of this class of method is such that the amount of work calculating one integration with parameters becomes that of two interpolations, when the system of nonlinear equations is solved on the right hand side function. The other class of method is the equivalence substitution method for avoiding calculating derivative on the right hand side function. In order to avoid calculation derivatives, two equivalence substitution methods are proposed here. The application instances of some special effect of the equivalence substitution methods are given.
文摘The following article has been retracted due to the investigation of complaints received against it. Mr. Mohammadali Ghorbani (corresponding author and also the last author) cheated the author’s name: Alireza Heidari. The scientific community takes a very strong view on this matter and we treat all unethical behavior such as plagiarism seriously. This paper published in Vol.3 No.3, 260-265, 2012, has been removed from this site.
基金This research was supported by the National Natural Science Foundation of China （Nos. 41230210 and 41204074）, the Science Foundation of the Education Department of Yunnan Province （No. 2013Z152）, and Statoil Company （Contract No. 4502502663）.
文摘We propose a symplectic partitioned Runge-Kutta （SPRK） method with eighth-order spatial accuracy based on the extended Hamiltonian system of the acoustic waveequation. Known as the eighth-order NSPRK method, this technique uses an eighth-orderaccurate nearly analytic discrete （NAD） operator to discretize high-order spatial differentialoperators and employs a second-order SPRK method to discretize temporal derivatives.The stability criteria and numerical dispersion relations of the eighth-order NSPRK methodare given by a semi-analytical method and are tested by numerical experiments. We alsoshow the differences of the numerical dispersions between the eighth-order NSPRK methodand conventional numerical methods such as the fourth-order NSPRK method, the eighth-order Lax-Wendroff correction （LWC） method and the eighth-order staggered-grid （SG）method. The result shows that the ability of the eighth-order NSPRK method to suppress thenumerical dispersion is obviously superior to that of the conventional numerical methods. Inthe same computational environment, to eliminate visible numerical dispersions, the eighth-order NSPRK is approximately 2.5 times faster than the fourth-order NSPRK and 3.4 timesfaster than the fourth-order SPRK, and the memory requirement is only approximately47.17% of the fourth-order NSPRK method and 49.41% of the fourth-order SPRK method,which indicates the highest computational efficiency. Modeling examples for the two-layermodels such as the heterogeneous and Marmousi models show that the wavefields generatedby the eighth-order NSPRK method are very clear with no visible numerical dispersion.These numerical experiments illustrate that the eighth-order NSPRK method can effectivelysuppress numerical dispersion when coarse grids are adopted. Therefore, this methodcan greatly decrease computer memory requirement and accelerate the forward modelingproductivity. In general, the eighth-order NSPRK method has tremendous potential value forseismic exploration and seismology research.
基金Project (10964004) supported by the National Natural Science Foundation of ChinaProject (20070731001) supported by Research Fund for the Doctoral Program of ChinaProject (096RJZA104) supported by the Natural Science Foundation of Gansu Province,China
文摘The influence of supercooled melt forced lamina flow on microsegregation was investigated. The concentration distribution at solid-liquid boundary of binary alloy Ni-Cu was simulated using phase field model coupled with flow field. The microsegregation, concentration maximum value, boundary thickness of concentration near upstream dendrite and normal to flow dendrite, and downstream dendrite were studied quantitatively in the case of forced lamia flow. The simulation results show that solute field and flow field interact complexly. Compared with melt without flow, in front of upstream dendrite tip, the concentration boundary thickness is the lowest and the concentration maximum value is the smallest for melt with flow. However, in front of downstream dendrite tip, the results are just the opposite. The zone of poor Cu in upstream dendrite where is the most severely microsegregation and shrinkage cavity is wider and the concentration is lower for melt with flow than that without flow.
基金The National Natural Science Foundation of China(No.51378121)the Fok Ying Tung Education Foundation(No.141076)the Scientific Innovation Research of College Graduates in Jiangsu Province(No.KYLX_0164)
文摘In order to predict the long-term rutting of asphalt pavement, the effective temperature for pavement rutting is calculated using the numerical simulation method. The transient temperature field of asphalt pavement was simulated based on actual meteorological data of Nanjing. 24-hour rutting development under a transient temperature field was calculated in each month. The rutting depth accumulated under the static temperature field was also estimated and the relationship between constant temperature parameters was analyzed. Then the effective temperature for pavement rutting was determined based on the rutting equivalence principle. The results show that the monthly effective temperature is above 40 t in July and August, while in June and September it ranges from 30 to 40 Rutting development can be ignored when the monthly effective temperature is less than 30 t. The yearly effective temperature for rutting in Nanjing is around 38. 5 t. The long-term rutting prediction model based on the effective temperature can reflect the influences of meteorological factors and traffic time distribution.
文摘LS-DYNA program and the principle of ALE method were introduced, and the target features of the reinforced concrete penetration were analyzed by using the D material model and the ALE method. A numerical simulation has been done to show the penetration visually and veritably. The simulation results are analyzed carefully and explicitly prove their significance to the research of reinforced concrete penetration.
