Groundwater is a vital component of the hydrological cycle and essential for the sustainable development of ecosystems.Numerical simulation methods are key tools for addressing scientific challenges in groundwater res...Groundwater is a vital component of the hydrological cycle and essential for the sustainable development of ecosystems.Numerical simulation methods are key tools for addressing scientific challenges in groundwater research.This study uses bibliometric visualization analysis to examine the progress and trends in groundwater numerical simulation methods.By analyzing literature indexed in the Web of Science database from January 1990 to February 2023,and employing tools such as Citespace and VOSviewer,we assessed publication volume,research institutions and their collaborations,prolific scholars,keyword clustering,and emerging trends.The findings indicate an overall upward trend in both the number of publications and citations concerning groundwater numerical simulations.Since 2010,the number of publications has tripled compared to the total before 2010,underscoring the increasing significance and potential of numerical simulation methods in groundwater science.China,in particular,has shown remarkable growth in this field over the past decade,surpassing the United States,Canada,and Germany.This progress is closely linked to strong national support and active participation from research institutions,especially the contributions from teams at Hohai University,China University of Geosciences,and the University of Science and Technology of China.Collaboration between research teams is primarily seen between China and the United States,with less noticeable cooperation among other countries,resulting in a diverse and dispersed development pattern.Keyword analysis highlights that international research hotspots include groundwater recharge,karst water,geothermal water migration,seawater intrusion,variable density flow,contaminant and solute transport,pollution remediation,and land subsidence.Looking ahead,groundwater numerical simulations are expected to play a more prominent role in areas such as climate change,surface water-groundwater interactions,the impact of groundwater nitrates on the environment and health,submarine groundwater discharge,ecological water use,groundwater management,and risk prevention.展开更多
According to the innate characteristic of four types of furnace, the copper flash continuous smelting （CFCS） furnace can be considered a synthetic reactor of two relatively independent processes： flash matte smelti...According to the innate characteristic of four types of furnace, the copper flash continuous smelting （CFCS） furnace can be considered a synthetic reactor of two relatively independent processes： flash matte smelting process （FMSP） and copper continuous converting process （CCCP）. Then, the CFCS thermodynamic model was proposed by establishing the multi-phase equilibrium model of FMSP and the local-equilibrium model of CCCP, respectively, and by combining them through the smelting intermediates. Subsequently, the influences of the furnace structures were investigated using the model on the formation of blister copper, the Fe3O4 behavior, the copper loss in slag and the copper recovery rate. The results show that the type D furnace, with double flues and a slag partition wall, is an ideal CFCS reactor compared with the other three types furnaces. For CFCS, it is effective to design a partition wall in the furnace to make FMSP and CCCP perform in two relatively independent zones, respectively, and to make smelting gas and converting gas discharge from respective flues.展开更多
Based on the Tropical Cyclone(TC briefly thereafter)Yearbook 1980-2009,this paper first analyzes the number and intensity change of the TCs which passed directly over or by the side of Poyang Lake(the distance of TC c...Based on the Tropical Cyclone(TC briefly thereafter)Yearbook 1980-2009,this paper first analyzes the number and intensity change of the TCs which passed directly over or by the side of Poyang Lake(the distance of TC center is less than 1°longitude or 1°latitude from the Lake)among all the landfalling TCs in China during the past 30 years.Two cases are examined in detail in this paper.One is severe typhoon Rananim with a speed of 3.26 m/s and a change of 1 hPa in intensity when it was passing the Lake.The other is super typhoon Saomai with a faster moving speed of 6.50 m/s and a larger change in intensity of 6 hPa.Through numerical simulation experiments,this paper analyzes how the change of underlying surface from water to land contributes to the differences in intensity,speed and mesoscale convection of the two TCs when they passed the Lake.Results show that the moisture and dynamic condition above the Lake were favorable for the maintenance of the intensity when Rananim was passing through Poyang Lake,despite the moisture supply from the ocean was cut off.As a result,there was strong convection around the lake which led to a rainfall spinning counter-clockwise as it was affected by the TC movement.However,little impact was seen in the Saomai case.These results indicate that for the TCs coming ashore on Poyang Lake with a slow speed,the large water body is conducive to the sustaining of the intensity and strengthening of the convection around the TC center and the subsequent heavy rainfall.On the contrary,a fast-moving TC is less likely to be influenced by the underlying surface in terms of intensity and speed.展开更多
A heavy storm rainfall caused by Typhoon Aere (No.0418) when landing at Fujian has been successfully simulated by using AREM model. The simulation result is scale-separated by spatial band-pass filtering, which reveal...A heavy storm rainfall caused by Typhoon Aere (No.0418) when landing at Fujian has been successfully simulated by using AREM model. The simulation result is scale-separated by spatial band-pass filtering, which reveals the mesoscale low pressure and convergence line that has direct impact on this rainfall process. The physical characteristics of the two mesoscale systems and their relation with rainfall are also analyzed. Study shows that there exists a well corresponding relationship between the storm rainfall and mesoscale divergence and strong updraft arising from the convergence, which is caused by the interactions between the mesoscale systems and topographic features, and is directly responsible for the rainfall.展开更多
Numerical simulation of careful parallel arithmetic of oil resources migration-accumulation of Tanhai Region ( three-layer) was done. Careful parallel operator splitting-up implicit iterative scheme, parallel arithmet...Numerical simulation of careful parallel arithmetic of oil resources migration-accumulation of Tanhai Region ( three-layer) was done. Careful parallel operator splitting-up implicit iterative scheme, parallel arithmetic program, parallel arithmetic information and alternating-direction mesh subdivision were put forward. Parallel arithmetic and analysis of different CPU combinations were done. This numerical simulation test and the actual conditions are basically coincident. The convergence estimation of the model problem has successfully solved the difficult problem in the fields of permeation fluid mechanics, computational mathematics and petroleum geology.展开更多
Deep shale reservoirs are characterized by elevated breakdown pressures,diminished fracture complexity,and reduced modified volumes compared to medium and shallow reservoirs.Therefore,it is urgent to investigate parti...Deep shale reservoirs are characterized by elevated breakdown pressures,diminished fracture complexity,and reduced modified volumes compared to medium and shallow reservoirs.Therefore,it is urgent to investigate particular injection strategies that can optimize breakdown pressure and fracturing efficiency to address the increasing demands for deep shale reservoir stimulation.In this study,the efficiency of various stimulation strategies,including multi-cluster simultaneous fracturing,modified alternating fracturing,alternating shut-in fracturing,and cyclic alternating fracturing,was evaluated.Subsequently,the sensitivity of factors such as the cycle index,shut-in time,cluster spacing,and horizontal permeability was investigated.Additionally,the flow distribution effect within the wellbore was discussed.The results indicate that relative to multi-cluster simultaneous fracturing,modified alternating fracturing exhibits reduced susceptibility to the stress shadow effect,which results in earlier breakdown,extended hydraulic fracture lengths,and more consistent propagation despite an increase in breakdown pressure.The alternating shut-in fracturing benefits the increase of fracture length,which is closely related to the shut-in time.Furthermore,cyclic alternating fracturing markedly lowers breakdown pressure and contributes to uniform fracture propagation,in which the cycle count plays an important role.Modified alternating fracturing demonstrates insensitivity to variations in cluster spacing,whereas horizontal permeability is a critical factor affecting fracture length.The wellbore effect restrains the accumulation of pressure and flow near the perforation,delaying the initiation of hydraulic fractures.The simulation results can provide valuable numerical insights for optimizing injection strategies for deep shale hydraulic fracturing.展开更多
The utilization of prefabricated light modular radiant heating system has demonstrated significant increases in heat transfer efficiency and energy conservation capabilities.Within prefabricated building construction,...The utilization of prefabricated light modular radiant heating system has demonstrated significant increases in heat transfer efficiency and energy conservation capabilities.Within prefabricated building construction,this new heating method presents an opportunity for the development of comprehensive facilities.The parameters for evaluating the effectiveness of such a system are the upper surface layer’s heat flux and temperature.In this paper,thermal resistance analysis calculation based on a simplified model for this unique radiant heating system analysis is presented with the heat transfer mechanism’s evaluation.The results obtained from thermal resistance analysis calculation and numerical simulation indicate that the thermal resistance analysis method is highly accurate with temperature discrepancies ranging from 0.44℃ to−0.44℃ and a heat flux discrepancy of less than 7.54%,which can meet the requirements of practical engineering applications,suggesting a foundation for the prefabricated radiant heating system.展开更多
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
In this paper,we consider the numerical implementation of the 2D wave equation in isotropic-heterogeneous media.The stability analysis of the scheme using the von Neumann stability method has been studied.We conducted...In this paper,we consider the numerical implementation of the 2D wave equation in isotropic-heterogeneous media.The stability analysis of the scheme using the von Neumann stability method has been studied.We conducted a study on modeling the propagation of acoustic waves in a heterogeneous medium and performed numerical simulations in various heterogeneous media at different time steps.Developed parallel code using Compute Unified Device Architecture(CUDA)technology and tested on domains of various sizes.Performance analysis showed that our parallel approach showed significant speedup compared to sequential code on the Central Processing Unit(CPU).The proposed parallel visualization simulator can be an important tool for numerous wave control systems in engineering practice.展开更多
Continental shale oil reservoirs,characterized by numerous bedding planes and micro-nano scale pores,feature significantly higher stress sensitivity compared to other types of reservoirs.However,research on suitable s...Continental shale oil reservoirs,characterized by numerous bedding planes and micro-nano scale pores,feature significantly higher stress sensitivity compared to other types of reservoirs.However,research on suitable stress sensitivity characterization models is still limited.In this study,three commonly used stress sensitivity models for shale oil reservoirs were considered,and experiments on representative core samples were conducted.By fitting and comparing the data,the“exponential model”was identified as a characterization model that accurately represents stress sensitivity in continental shale oil reservoirs.To validate the accuracy of the model,a two-phase seepage mathematical model for shale oil reservoirs coupled with the exponential model was introduced.The model was discretely solved using the finite volume method,and its accuracy was verified through the commercial simulator CMG.The study evaluated the productivity of a typical horizontal well under different engineering,geological,and fracture conditions.The results indicate that considering stress sensitivity leads to a 13.57%reduction in production for the same matrix permeability.Additionally,as the fracture half-length and the number of fractures increase,and the bottomhole flowing pressure decreases,the reservoir stress sensitivity becomes higher.展开更多
Multistage multi-cluster hydraulic fracturing has enabled the economic exploitation of shale reservoirs,but the interpretation of hydraulic fracture parameters is challenging.The pressure signals after pump shutdown a...Multistage multi-cluster hydraulic fracturing has enabled the economic exploitation of shale reservoirs,but the interpretation of hydraulic fracture parameters is challenging.The pressure signals after pump shutdown are influenced by hydraulic fractures,which can reflect the geometric features of hydraulic fracture.The shutdown pressure can be used to interpret the hydraulic fracture parameters in a real-time and cost-effective manner.In this paper,a mathematical model for shutdown pressure evolution is developed considering the effects of wellbore friction,perforation friction and fluid loss in fractures.An efficient numerical simulation method is established by using the method of characteristics.Based on this method,the impacts of fracture half-length,fracture height,opened cluster and perforation number,and filtration coefficient on the evolution of shutdown pressure are analyzed.The results indicate that a larger fracture half-length may hasten the decay of shutdown pressure,while a larger fracture height can slow down the decay of shutdown pressure.A smaller number of opened clusters and perforations can significantly increase the perforation friction and decrease the overall level of shutdown pressure.A larger filtration coefficient may accelerate the fluid filtration in the fracture and hasten the drop of the shutdown pressure.The simulation method of shutdown pressure,as well as the analysis results,has important implications for the interpretation of hydraulic fracture parameters.展开更多
Objective With the cranial aneurysm’s 3D-computational hemodynamics numerical simulation,we can get the cranial aneurysms and its ’s mother arteries ’blood flow rate,path and wall shearing stress and so on. Taking ...Objective With the cranial aneurysm’s 3D-computational hemodynamics numerical simulation,we can get the cranial aneurysms and its ’s mother arteries ’blood flow rate,path and wall shearing stress and so on. Taking use of the contrast analysis of the hemodynamics result and the findings in operation,we try to find hemodynamic character and mechanism of rupture展开更多
A numerical program is built to simulate the performance of a spark ignited two-stroke free-piston engine coupled with a linear generator. The computational model combines a series of dynamic and thermodynamic equatio...A numerical program is built to simulate the performance of a spark ignited two-stroke free-piston engine coupled with a linear generator. The computational model combines a series of dynamic and thermodynamic equations that are solved simultaneously to predict the performances of the engines. The dynamic analysis performed consists of an evaluation of the frictional force and load force introduced by the generator. The thermodynamic analysis used a single zone model to describe the engine＇ s working cycle which includes intake, scavenging, compression, combustion and expansion, and to evaluate the effect of heat transfer based on the first law of thermodynamics and the ideal gas state equation. Because there is no crankshaft, a time based Wiebe equation was used to express the fraction of fuel burned in the combustion. The calculated results were validated by using the experimental data from another research group. The results indicate that the free-piston generator has some advantages over conventional engines.展开更多
Current research on pump-turbine units is focused on the unstable operation at off-design conditions, with the characteristic curves in generating mode being S-shaped. Unlike in the traditional water turbines, pump-tu...Current research on pump-turbine units is focused on the unstable operation at off-design conditions, with the characteristic curves in generating mode being S-shaped. Unlike in the traditional water turbines, pump-turbine operation along the S-shaped curve can lead to difficulties during load rejection with unusual increases in the water pressure, which leads to machine vibrations. This paper describes both model tests and numerical simulations. A reduced scale model of a low specific speed pump-turbine was used for the performance tests, with comparisons to computational fluid dynamics（CFD） results. Predictions using the detached eddy simulation（DES） turbulence model, which is a combined Reynolds averaged Naviers-Stokes（RANS） and large eddy simulation（LES） model, are compared with the two-equation turbulence mode results. The external characteristics as well as the internal flow are for various guide vane openings to understand the unsteady flow along the so called S characteristics of a pump-turbine. Comparison of the experimental data with the CFD results for various conditions and times shows that DES model gives better agreement with experimental data than the two-equation turbulence model. For low flow conditions, the centrifugal forces and the large incident angle create large vortices between the guide vanes and the runner inlet in the runner passage, which is the main factor leading to the S-shaped characteristics. The turbulence model used here gives more accurate simulations of the internal flow characteristics of the pump-turbine and a more detailed force analysis which shows the mechanisms controlling of the S characteristics.展开更多
For high-steep slopes in hydropower engineering, damage can be induced or accumulated due to a seriesof human or natural activities, including excavation, dam construction, earthquake, rainstorm, rapid riseor drop of ...For high-steep slopes in hydropower engineering, damage can be induced or accumulated due to a seriesof human or natural activities, including excavation, dam construction, earthquake, rainstorm, rapid riseor drop of water level in the service lifetime of slopes. According to the concept that the progressivedamage （microseismicity） of rock slope is the essence of the precursor of slope instability, a microseismicmonitoring system for high-steep rock slopes is established. Positioning accuracy of the monitoringsystem is tested by fixed-position blasting method. Based on waveform and cluster analyses of microseismicevents recorded during test, the tempo-spatial distribution of microseismic events is analyzed.The deformation zone in the deep rock masses induced by the microseismic events is preliminarilydelimited. Based on the physical information measured by in situ microseismic monitoring, an evaluationmethod for the dynamic stability of rock slopes is proposed and preliminarily implemented bycombining microseismic monitoring and numerical modeling. Based on the rock mass damage modelobtained by back analysis of microseismic information, the rock mass elements within the microseismicdamage zone are automatically searched by finite element program. Then the stiffness and strengthreductions are performed on these damaged elements accordingly. Attempts are made to establish thecorrelation between microseismic event, strength deterioration and slope dynamic instability, so as toquantitatively evaluate the dynamic stability of slope. The case studies about two practical slopes indicatethat the proposed method can reflect the factor of safety of rock slope more objectively. Numericalanalysis can help to understand the characteristics and modes of the monitored microseismic events inrock slopes. Microseismic monitoring data and simulation results can be used to mutually modify thesensitive rock parameters and calibrate the model. Combination of microseismic monitoring and numericalsimulation provides a more objective basis for the numerical model and parameters and a solidmechanical foundation for the microseismic monitoring.展开更多
In hard target penetration simulation, the existing researches of the convergence of results are mainly concentrating in the corresponding relationship between penetration depth and mesh scales. However, the influence...In hard target penetration simulation, the existing researches of the convergence of results are mainly concentrating in the corresponding relationship between penetration depth and mesh scales. However, the influence of the mesh difference on the penetration resistance and acceleration signals are seldom refer to. This paper presents the occurring mechanism and restraining method of numerical noise signal in penetration simulation. First, the concept of the noise signal izs proposed. By taking a 3D penetration simulation as example, the influence of the noise signal on the penetration resistance in different mesh scales and impact velocity is studied. To ensure the convergence of the computational results, the grid scale of the target is encrypted to 1：1：8. In addition, modem spectrum analysis method is introduced to further analyze the penetration resistance signal. The research results presented is useful to improve the computational accuracy of high speed projectile penetration simulation, and provide important reference for carrying out structural design and optimization of fuze system.展开更多
In this paper. :LDDA (Lagrangian Discontinuous Deformation Analysis) method is used in modeling thedynamic process of the M,=7.8 Tang shan earthquake on July 28, 1976 and obtain directly the dynamic and quasi static d...In this paper. :LDDA (Lagrangian Discontinuous Deformation Analysis) method is used in modeling thedynamic process of the M,=7.8 Tang shan earthquake on July 28, 1976 and obtain directly the dynamic and quasi static dislocations. shear stress drops, fracture velocities of the Tang shan earthquake fault. The simulation showsthai the slip history at each point of the fault is different. The displacement vectors at the concave side of the faultis greater than that of the convex side of the fault. The 'over shoot' of the fault slip is greatest at the middle part ofthe fault and attenuates to its ends. The rupture velocities of the fault from the epicenter towards south-west andtowards north-east are 3.08 m/s and 1. 18 m/s, respectively, the average one is 2.13 In/s. The maximum dynamic.m quasi-static dislocations are 7. 1 m and 6.2 m respectively. the average quasi-static one on the fault is 4.5 m.initial stress dynamic and quasi-static shear stress drops are 8.1 M Pa and 5.4 MP4 respectively, the averagequasi-static shear stress drop is 3.9 M Pa. We found that the rupture velocities and shear stress are related to theinitial stress states of the fault.展开更多
In coalmines of China, horizontal directional drilling （HDD） is an increasingly popular method for underground in-seam gas drainage. Numerical simulation, especially finite element analysis, is often used as an effe...In coalmines of China, horizontal directional drilling （HDD） is an increasingly popular method for underground in-seam gas drainage. Numerical simulation, especially finite element analysis, is often used as an effective method to improve HDD operation. These improvements focus on rock-breaking efficiency, directional precision, stability of the borehole wall, and reliability of the drill equipment. On the basis of underground drilling characteristics, typical numerical simulation exam- ples in drilling techniques and equipment are summarized and analyzed. In the end, the future development trends of numerical simulation in underground in-seam drilling are proposed.展开更多
This study aims to analyze the influence of vortex motion in a reverse Stairmand cyclone separator by using LES model.The mathematical analysis indicated that the energy dissipation and the flow characteristics of inc...This study aims to analyze the influence of vortex motion in a reverse Stairmand cyclone separator by using LES model.The mathematical analysis indicated that the energy dissipation and the flow characteristics of incompressible fluid are directly related to on the vortex motion.The results of the Q criterion-based iso-vortex surface could well reflect the tendency of the vortex structure,in which the iso-vortex surface exhibited a distorted distribution rather than around the center axis.At the turning point of velocity vector,vortices were formed and developed,and the point was the center of the local vortex core.In addition,the vortex formed an irregular annular region around the wall at the bottom of vortex finder.The vortex structure near the dust hopper presented a strong distortion.Moreover,there were two rotating flow in the opposite direction within the dust hopper.These phenomena would affect the separation performance,which was significance to cyclone separator.展开更多
The mean wind-induced interference effects between two high-rise buildings,in which the interfering buildings have different heights,were numerical simulated in the terrain roughness of B and D types by the Reynolds s...The mean wind-induced interference effects between two high-rise buildings,in which the interfering buildings have different heights,were numerical simulated in the terrain roughness of B and D types by the Reynolds stress equation model(RSM)of fluent.The results are in good agreement with those of the wind tunnel test.Influences of the relative arrangement of two buildings,the height of the interfering buildings and the terrain roughness upon the mean interference effects were analyzed,and the space distributions of IFCPs on the principal building under tandem arrangement were studied.The results indicate that the lower interfering buildings can always bring larger interference factors comparing to the higher ones under tandem arrangement except that the height is larger than 1.25h,and the heights' influence on the mean interference effects will increase as the reduced spacing of two buildings.The influence of heights will be little under stagger arrangement.展开更多
基金supported by the Institute of Hydrogeology and Environmental Geology,China Geological Survey"Coupling analysis of groundwater and land subsidence in typical cities of the North China Plain based on InSAR-GRACE technology"project under Grant No.KY202302the China Geological Survey"Research and promotion of digital water resources survey technology"project under Grant No.DD20230427the"Cloud platform geological survey node operation and maintenance and network security guarantee(Institute of Hydrogeology and Environmental Geology)"project under Grant No.DD20230719.
文摘Groundwater is a vital component of the hydrological cycle and essential for the sustainable development of ecosystems.Numerical simulation methods are key tools for addressing scientific challenges in groundwater research.This study uses bibliometric visualization analysis to examine the progress and trends in groundwater numerical simulation methods.By analyzing literature indexed in the Web of Science database from January 1990 to February 2023,and employing tools such as Citespace and VOSviewer,we assessed publication volume,research institutions and their collaborations,prolific scholars,keyword clustering,and emerging trends.The findings indicate an overall upward trend in both the number of publications and citations concerning groundwater numerical simulations.Since 2010,the number of publications has tripled compared to the total before 2010,underscoring the increasing significance and potential of numerical simulation methods in groundwater science.China,in particular,has shown remarkable growth in this field over the past decade,surpassing the United States,Canada,and Germany.This progress is closely linked to strong national support and active participation from research institutions,especially the contributions from teams at Hohai University,China University of Geosciences,and the University of Science and Technology of China.Collaboration between research teams is primarily seen between China and the United States,with less noticeable cooperation among other countries,resulting in a diverse and dispersed development pattern.Keyword analysis highlights that international research hotspots include groundwater recharge,karst water,geothermal water migration,seawater intrusion,variable density flow,contaminant and solute transport,pollution remediation,and land subsidence.Looking ahead,groundwater numerical simulations are expected to play a more prominent role in areas such as climate change,surface water-groundwater interactions,the impact of groundwater nitrates on the environment and health,submarine groundwater discharge,ecological water use,groundwater management,and risk prevention.
基金Project (50904027) supported by the National Natural Science Foundation of ChinaProject (2013BAB03B05) supported by the National Key Technology R&D Program of China+1 种基金Project (20133BCB23018) supported by the Foundation for Young Scientist(Jinggang Star)of Jiangxi Province,ChinaProject (2012ZBAB206002) supported by the Natural Science Foundation of Jiangxi Province,China
文摘According to the innate characteristic of four types of furnace, the copper flash continuous smelting （CFCS） furnace can be considered a synthetic reactor of two relatively independent processes： flash matte smelting process （FMSP） and copper continuous converting process （CCCP）. Then, the CFCS thermodynamic model was proposed by establishing the multi-phase equilibrium model of FMSP and the local-equilibrium model of CCCP, respectively, and by combining them through the smelting intermediates. Subsequently, the influences of the furnace structures were investigated using the model on the formation of blister copper, the Fe3O4 behavior, the copper loss in slag and the copper recovery rate. The results show that the type D furnace, with double flues and a slag partition wall, is an ideal CFCS reactor compared with the other three types furnaces. For CFCS, it is effective to design a partition wall in the furnace to make FMSP and CCCP perform in two relatively independent zones, respectively, and to make smelting gas and converting gas discharge from respective flues.
基金China National Science Foundation(40730948,41075037,41175063)Special Project of Chinese Academy of Meteorological Sciences(2007Y006)
文摘Based on the Tropical Cyclone(TC briefly thereafter)Yearbook 1980-2009,this paper first analyzes the number and intensity change of the TCs which passed directly over or by the side of Poyang Lake(the distance of TC center is less than 1°longitude or 1°latitude from the Lake)among all the landfalling TCs in China during the past 30 years.Two cases are examined in detail in this paper.One is severe typhoon Rananim with a speed of 3.26 m/s and a change of 1 hPa in intensity when it was passing the Lake.The other is super typhoon Saomai with a faster moving speed of 6.50 m/s and a larger change in intensity of 6 hPa.Through numerical simulation experiments,this paper analyzes how the change of underlying surface from water to land contributes to the differences in intensity,speed and mesoscale convection of the two TCs when they passed the Lake.Results show that the moisture and dynamic condition above the Lake were favorable for the maintenance of the intensity when Rananim was passing through Poyang Lake,despite the moisture supply from the ocean was cut off.As a result,there was strong convection around the lake which led to a rainfall spinning counter-clockwise as it was affected by the TC movement.However,little impact was seen in the Saomai case.These results indicate that for the TCs coming ashore on Poyang Lake with a slow speed,the large water body is conducive to the sustaining of the intensity and strengthening of the convection around the TC center and the subsequent heavy rainfall.On the contrary,a fast-moving TC is less likely to be influenced by the underlying surface in terms of intensity and speed.
文摘A heavy storm rainfall caused by Typhoon Aere (No.0418) when landing at Fujian has been successfully simulated by using AREM model. The simulation result is scale-separated by spatial band-pass filtering, which reveals the mesoscale low pressure and convergence line that has direct impact on this rainfall process. The physical characteristics of the two mesoscale systems and their relation with rainfall are also analyzed. Study shows that there exists a well corresponding relationship between the storm rainfall and mesoscale divergence and strong updraft arising from the convergence, which is caused by the interactions between the mesoscale systems and topographic features, and is directly responsible for the rainfall.
基金Project supported by the National Natural Science Foundation of China (Nos. 10372052 and 10271066)the Major State Basic Research Program of China (No. 1999032803)the Special Fund of PhD Program of Education Ministry of China (No. 20030422047)
文摘Numerical simulation of careful parallel arithmetic of oil resources migration-accumulation of Tanhai Region ( three-layer) was done. Careful parallel operator splitting-up implicit iterative scheme, parallel arithmetic program, parallel arithmetic information and alternating-direction mesh subdivision were put forward. Parallel arithmetic and analysis of different CPU combinations were done. This numerical simulation test and the actual conditions are basically coincident. The convergence estimation of the model problem has successfully solved the difficult problem in the fields of permeation fluid mechanics, computational mathematics and petroleum geology.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.42377156,42077251 and 42202305).
文摘Deep shale reservoirs are characterized by elevated breakdown pressures,diminished fracture complexity,and reduced modified volumes compared to medium and shallow reservoirs.Therefore,it is urgent to investigate particular injection strategies that can optimize breakdown pressure and fracturing efficiency to address the increasing demands for deep shale reservoir stimulation.In this study,the efficiency of various stimulation strategies,including multi-cluster simultaneous fracturing,modified alternating fracturing,alternating shut-in fracturing,and cyclic alternating fracturing,was evaluated.Subsequently,the sensitivity of factors such as the cycle index,shut-in time,cluster spacing,and horizontal permeability was investigated.Additionally,the flow distribution effect within the wellbore was discussed.The results indicate that relative to multi-cluster simultaneous fracturing,modified alternating fracturing exhibits reduced susceptibility to the stress shadow effect,which results in earlier breakdown,extended hydraulic fracture lengths,and more consistent propagation despite an increase in breakdown pressure.The alternating shut-in fracturing benefits the increase of fracture length,which is closely related to the shut-in time.Furthermore,cyclic alternating fracturing markedly lowers breakdown pressure and contributes to uniform fracture propagation,in which the cycle count plays an important role.Modified alternating fracturing demonstrates insensitivity to variations in cluster spacing,whereas horizontal permeability is a critical factor affecting fracture length.The wellbore effect restrains the accumulation of pressure and flow near the perforation,delaying the initiation of hydraulic fractures.The simulation results can provide valuable numerical insights for optimizing injection strategies for deep shale hydraulic fracturing.
基金Project(NB-2020-JG-07)supported by the Research and Engineering Application of Key Technologies for New Building Industrialization Project of China Northwest Architectural Design and Research Institute Co.,Ltd.Project(2023-CXTD-29)supported by the Key Scientific and Technological Innovation Team of Shaanxi Province,ChinaProject supported by the K.C.Wong Education Foundation。
文摘The utilization of prefabricated light modular radiant heating system has demonstrated significant increases in heat transfer efficiency and energy conservation capabilities.Within prefabricated building construction,this new heating method presents an opportunity for the development of comprehensive facilities.The parameters for evaluating the effectiveness of such a system are the upper surface layer’s heat flux and temperature.In this paper,thermal resistance analysis calculation based on a simplified model for this unique radiant heating system analysis is presented with the heat transfer mechanism’s evaluation.The results obtained from thermal resistance analysis calculation and numerical simulation indicate that the thermal resistance analysis method is highly accurate with temperature discrepancies ranging from 0.44℃ to−0.44℃ and a heat flux discrepancy of less than 7.54%,which can meet the requirements of practical engineering applications,suggesting a foundation for the prefabricated radiant heating system.
基金the National Natural Science Foundation of China(No.51875062,No.52205336)the China Postdoctoral Science Foundation(No.2021M700567).
文摘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.
基金funded by the Committee of Science of the Ministry of Science and Higher Education of the Republic of Kazakhstan(Grants No.AP14972032)NT is also supported by the Beatriu de Pinós programme and by AGAUR(Generalitat de Catalunya)grant 2021 SGR 00087.
文摘In this paper,we consider the numerical implementation of the 2D wave equation in isotropic-heterogeneous media.The stability analysis of the scheme using the von Neumann stability method has been studied.We conducted a study on modeling the propagation of acoustic waves in a heterogeneous medium and performed numerical simulations in various heterogeneous media at different time steps.Developed parallel code using Compute Unified Device Architecture(CUDA)technology and tested on domains of various sizes.Performance analysis showed that our parallel approach showed significant speedup compared to sequential code on the Central Processing Unit(CPU).The proposed parallel visualization simulator can be an important tool for numerous wave control systems in engineering practice.
基金supported by the China Postdoctoral Science Foundation(2021M702304)Natural Science Foundation of Shandong Province(ZR2021QE260).
文摘Continental shale oil reservoirs,characterized by numerous bedding planes and micro-nano scale pores,feature significantly higher stress sensitivity compared to other types of reservoirs.However,research on suitable stress sensitivity characterization models is still limited.In this study,three commonly used stress sensitivity models for shale oil reservoirs were considered,and experiments on representative core samples were conducted.By fitting and comparing the data,the“exponential model”was identified as a characterization model that accurately represents stress sensitivity in continental shale oil reservoirs.To validate the accuracy of the model,a two-phase seepage mathematical model for shale oil reservoirs coupled with the exponential model was introduced.The model was discretely solved using the finite volume method,and its accuracy was verified through the commercial simulator CMG.The study evaluated the productivity of a typical horizontal well under different engineering,geological,and fracture conditions.The results indicate that considering stress sensitivity leads to a 13.57%reduction in production for the same matrix permeability.Additionally,as the fracture half-length and the number of fractures increase,and the bottomhole flowing pressure decreases,the reservoir stress sensitivity becomes higher.
基金The work is supported by the Sub-Project of“Research on Key Technologies and Equipment of Reservoir Stimulation”of China National Petroleum Corporation Post–14th Five-Year Plan Forward-Looking Major Science and Technology Project“Research on New Technology of Monitoring and Diagnosis of Horizontal Well Hydraulic Fracture Network Distribution Pattern”(2021DJ4502).
文摘Multistage multi-cluster hydraulic fracturing has enabled the economic exploitation of shale reservoirs,but the interpretation of hydraulic fracture parameters is challenging.The pressure signals after pump shutdown are influenced by hydraulic fractures,which can reflect the geometric features of hydraulic fracture.The shutdown pressure can be used to interpret the hydraulic fracture parameters in a real-time and cost-effective manner.In this paper,a mathematical model for shutdown pressure evolution is developed considering the effects of wellbore friction,perforation friction and fluid loss in fractures.An efficient numerical simulation method is established by using the method of characteristics.Based on this method,the impacts of fracture half-length,fracture height,opened cluster and perforation number,and filtration coefficient on the evolution of shutdown pressure are analyzed.The results indicate that a larger fracture half-length may hasten the decay of shutdown pressure,while a larger fracture height can slow down the decay of shutdown pressure.A smaller number of opened clusters and perforations can significantly increase the perforation friction and decrease the overall level of shutdown pressure.A larger filtration coefficient may accelerate the fluid filtration in the fracture and hasten the drop of the shutdown pressure.The simulation method of shutdown pressure,as well as the analysis results,has important implications for the interpretation of hydraulic fracture parameters.
文摘Objective With the cranial aneurysm’s 3D-computational hemodynamics numerical simulation,we can get the cranial aneurysms and its ’s mother arteries ’blood flow rate,path and wall shearing stress and so on. Taking use of the contrast analysis of the hemodynamics result and the findings in operation,we try to find hemodynamic character and mechanism of rupture
文摘A numerical program is built to simulate the performance of a spark ignited two-stroke free-piston engine coupled with a linear generator. The computational model combines a series of dynamic and thermodynamic equations that are solved simultaneously to predict the performances of the engines. The dynamic analysis performed consists of an evaluation of the frictional force and load force introduced by the generator. The thermodynamic analysis used a single zone model to describe the engine＇ s working cycle which includes intake, scavenging, compression, combustion and expansion, and to evaluate the effect of heat transfer based on the first law of thermodynamics and the ideal gas state equation. Because there is no crankshaft, a time based Wiebe equation was used to express the fraction of fuel burned in the combustion. The calculated results were validated by using the experimental data from another research group. The results indicate that the free-piston generator has some advantages over conventional engines.
基金Supported by National Natural Science Foundation of China(Grant No.51139007)State Key Laboratory of Hydroscience and Engineering Open Foundation of China(Grant No.2014-KY-05)
文摘Current research on pump-turbine units is focused on the unstable operation at off-design conditions, with the characteristic curves in generating mode being S-shaped. Unlike in the traditional water turbines, pump-turbine operation along the S-shaped curve can lead to difficulties during load rejection with unusual increases in the water pressure, which leads to machine vibrations. This paper describes both model tests and numerical simulations. A reduced scale model of a low specific speed pump-turbine was used for the performance tests, with comparisons to computational fluid dynamics（CFD） results. Predictions using the detached eddy simulation（DES） turbulence model, which is a combined Reynolds averaged Naviers-Stokes（RANS） and large eddy simulation（LES） model, are compared with the two-equation turbulence mode results. The external characteristics as well as the internal flow are for various guide vane openings to understand the unsteady flow along the so called S characteristics of a pump-turbine. Comparison of the experimental data with the CFD results for various conditions and times shows that DES model gives better agreement with experimental data than the two-equation turbulence model. For low flow conditions, the centrifugal forces and the large incident angle create large vortices between the guide vanes and the runner inlet in the runner passage, which is the main factor leading to the S-shaped characteristics. The turbulence model used here gives more accurate simulations of the internal flow characteristics of the pump-turbine and a more detailed force analysis which shows the mechanisms controlling of the S characteristics.
基金supported by grants from the National Basic Research Program of China (Grant Nos. 2011CB013503, 2014CB047103)the National Natural Science Foundation of China (Grant Nos. 51279024, 51209127)
文摘For high-steep slopes in hydropower engineering, damage can be induced or accumulated due to a seriesof human or natural activities, including excavation, dam construction, earthquake, rainstorm, rapid riseor drop of water level in the service lifetime of slopes. According to the concept that the progressivedamage （microseismicity） of rock slope is the essence of the precursor of slope instability, a microseismicmonitoring system for high-steep rock slopes is established. Positioning accuracy of the monitoringsystem is tested by fixed-position blasting method. Based on waveform and cluster analyses of microseismicevents recorded during test, the tempo-spatial distribution of microseismic events is analyzed.The deformation zone in the deep rock masses induced by the microseismic events is preliminarilydelimited. Based on the physical information measured by in situ microseismic monitoring, an evaluationmethod for the dynamic stability of rock slopes is proposed and preliminarily implemented bycombining microseismic monitoring and numerical modeling. Based on the rock mass damage modelobtained by back analysis of microseismic information, the rock mass elements within the microseismicdamage zone are automatically searched by finite element program. Then the stiffness and strengthreductions are performed on these damaged elements accordingly. Attempts are made to establish thecorrelation between microseismic event, strength deterioration and slope dynamic instability, so as toquantitatively evaluate the dynamic stability of slope. The case studies about two practical slopes indicatethat the proposed method can reflect the factor of safety of rock slope more objectively. Numericalanalysis can help to understand the characteristics and modes of the monitored microseismic events inrock slopes. Microseismic monitoring data and simulation results can be used to mutually modify thesensitive rock parameters and calibrate the model. Combination of microseismic monitoring and numericalsimulation provides a more objective basis for the numerical model and parameters and a solidmechanical foundation for the microseismic monitoring.
基金Supported by National Natural Science Foundation of China(Grant No.11372047)
文摘In hard target penetration simulation, the existing researches of the convergence of results are mainly concentrating in the corresponding relationship between penetration depth and mesh scales. However, the influence of the mesh difference on the penetration resistance and acceleration signals are seldom refer to. This paper presents the occurring mechanism and restraining method of numerical noise signal in penetration simulation. First, the concept of the noise signal izs proposed. By taking a 3D penetration simulation as example, the influence of the noise signal on the penetration resistance in different mesh scales and impact velocity is studied. To ensure the convergence of the computational results, the grid scale of the target is encrypted to 1：1：8. In addition, modem spectrum analysis method is introduced to further analyze the penetration resistance signal. The research results presented is useful to improve the computational accuracy of high speed projectile penetration simulation, and provide important reference for carrying out structural design and optimization of fuze system.
文摘In this paper. :LDDA (Lagrangian Discontinuous Deformation Analysis) method is used in modeling thedynamic process of the M,=7.8 Tang shan earthquake on July 28, 1976 and obtain directly the dynamic and quasi static dislocations. shear stress drops, fracture velocities of the Tang shan earthquake fault. The simulation showsthai the slip history at each point of the fault is different. The displacement vectors at the concave side of the faultis greater than that of the convex side of the fault. The 'over shoot' of the fault slip is greatest at the middle part ofthe fault and attenuates to its ends. The rupture velocities of the fault from the epicenter towards south-west andtowards north-east are 3.08 m/s and 1. 18 m/s, respectively, the average one is 2.13 In/s. The maximum dynamic.m quasi-static dislocations are 7. 1 m and 6.2 m respectively. the average quasi-static one on the fault is 4.5 m.initial stress dynamic and quasi-static shear stress drops are 8.1 M Pa and 5.4 MP4 respectively, the averagequasi-static shear stress drop is 3.9 M Pa. We found that the rupture velocities and shear stress are related to theinitial stress states of the fault.
基金Supported by the National Natural Science Foundation of China （50805010） the Natural Science Foundation of Shaanxi Province （2011JM70 17）
文摘In coalmines of China, horizontal directional drilling （HDD） is an increasingly popular method for underground in-seam gas drainage. Numerical simulation, especially finite element analysis, is often used as an effective method to improve HDD operation. These improvements focus on rock-breaking efficiency, directional precision, stability of the borehole wall, and reliability of the drill equipment. On the basis of underground drilling characteristics, typical numerical simulation exam- ples in drilling techniques and equipment are summarized and analyzed. In the end, the future development trends of numerical simulation in underground in-seam drilling are proposed.
基金support from and the Scientific Research Staring Foundation of Hainan University,No.KYQD(ZR)20042Young Talents’Science and Technology Innovation Project of Hainan Association for Science and Technology,No.QCXM202027supported by Hainan Provincial Natural Science Foundation of China,No.520QN228
文摘This study aims to analyze the influence of vortex motion in a reverse Stairmand cyclone separator by using LES model.The mathematical analysis indicated that the energy dissipation and the flow characteristics of incompressible fluid are directly related to on the vortex motion.The results of the Q criterion-based iso-vortex surface could well reflect the tendency of the vortex structure,in which the iso-vortex surface exhibited a distorted distribution rather than around the center axis.At the turning point of velocity vector,vortices were formed and developed,and the point was the center of the local vortex core.In addition,the vortex formed an irregular annular region around the wall at the bottom of vortex finder.The vortex structure near the dust hopper presented a strong distortion.Moreover,there were two rotating flow in the opposite direction within the dust hopper.These phenomena would affect the separation performance,which was significance to cyclone separator.
基金the National Natural Science Foundation of China(Grant No.59895410)
文摘The mean wind-induced interference effects between two high-rise buildings,in which the interfering buildings have different heights,were numerical simulated in the terrain roughness of B and D types by the Reynolds stress equation model(RSM)of fluent.The results are in good agreement with those of the wind tunnel test.Influences of the relative arrangement of two buildings,the height of the interfering buildings and the terrain roughness upon the mean interference effects were analyzed,and the space distributions of IFCPs on the principal building under tandem arrangement were studied.The results indicate that the lower interfering buildings can always bring larger interference factors comparing to the higher ones under tandem arrangement except that the height is larger than 1.25h,and the heights' influence on the mean interference effects will increase as the reduced spacing of two buildings.The influence of heights will be little under stagger arrangement.
