Particle transport is a fundamental aspect of various systems,from artificial to biological.A common assumption is that particle motion follows Markovian(memoryless)processes in the absence of interaction between part...Particle transport is a fundamental aspect of various systems,from artificial to biological.A common assumption is that particle motion follows Markovian(memoryless)processes in the absence of interaction between particles.However,hydrodynamic memory and the interaction between particles are ubiquitous,leaving many fundamental questions unanswered regarding transport of interacting particles involving hydrodynamic drag in corrugated channels,as described by the fractional Langevin equation.This study examines the hydrodynamic transport of interacting non-Brownian particles moving within a corrugated channel.We propose a method that relies on factors such as temperature,the driving force to alternate between no transport and finite net transport.Of importance is to note that the absence of transport results from the clogging,while the transport consists of collective motion and independent motion.The transport systems investigated in this work suggest the potential for sensor functionality within the system.Our findings may prove valuable for exploring the transport with hydrodynamic memory in various fields,including biology,physics,and chemistry.展开更多
Understanding the motion behaviors of non-metallic inclusions in the liquid metal is important for clean steel production.High-temperature confocal laser scanning microscopy is applied to investigate the effect of dif...Understanding the motion behaviors of non-metallic inclusions in the liquid metal is important for clean steel production.High-temperature confocal laser scanning microscopy is applied to investigate the effect of different Ti and Al contents on the agglomeration behavior of non-metallic inclusions in low carbon steels.Furthermore,the agglomeration mechanism of inclusions was investigated through quantitative analysis of in-situ observation experiments and a modified Kralchevsky-Paunov model.The obtained results indicate that Al_(2)O_(3)is the main type inclusion in the low-alloys steels with both Al and Ti addition.This type of inclusion is more likely to absorb surrounding small-size inclusion particles,leading to a further growth for the cluster formation and contributing to a serious engineering problem,nozzle clogging.Besides,TiO_(x)is the main type inclusion in the molten steel with only Ti addition,and this type of inclusion is less likely to agglomerate and the individual inclusion particles show a‘free’motion with the fluid of molten steel.The difference between these two types of inclusions is due to the difference in attractive force and action distance at the meniscus created by the inclusion/steel/Ar multiple interfaces and influenced by the physical parameters,e.g.,contact angle and interface energy between inclusion and steel,and surface tension of the melt.展开更多
Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,...Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.展开更多
To fundamentally alleviate the excavation chamber clogging during slurry tunnel boring machine(TBM)advancing in hard rock,large-diameter short screw conveyor was adopted to slurry TBM of Qingdao Jiaozhou Bay Second Un...To fundamentally alleviate the excavation chamber clogging during slurry tunnel boring machine(TBM)advancing in hard rock,large-diameter short screw conveyor was adopted to slurry TBM of Qingdao Jiaozhou Bay Second Undersea Tunnel.To evaluate the discharging performance of short screw conveyor in different cases,the full-scale transient slurry-rock two-phase model for a short screw conveyor actively discharging rocks was established using computational fluid dynamics-discrete element method(CFD-DEM)coupling approach.In the fluid domain of coupling model,the sliding mesh technology was utilized to describe the rotations of the atmospheric composite cutterhead and the short screw conveyor.In the particle domain of coupling model,the dynamic particle factories were established to produce rock particles with the rotation of the cutterhead.And the accuracy and reliability of the CFD-DEM simulation results were validated via the field test and model test.Furthermore,a comprehensive parameter analysis was conducted to examine the effects of TBM operating parameters,the geometric design of screw conveyor and the size of rocks on the discharging performance of short screw conveyor.Accordingly,a reasonable rotational speed of screw conveyor was suggested and applied to Jiaozhou Bay Second Undersea Tunnel project.The findings in this paper could provide valuable references for addressing the excavation chamber clogging during ultra-large-diameter slurry TBM tunneling in hard rock for similar future.展开更多
In unconsolidated sandstone reservoirs,presence of numerous movable grains and a complex grain size composition necessitates a clear understanding of the physical clogging process for effective groundwater recharge in...In unconsolidated sandstone reservoirs,presence of numerous movable grains and a complex grain size composition necessitates a clear understanding of the physical clogging process for effective groundwater recharge in groundwater-source heat pump systems.To investigate this,a series of seepage experiments was conducted under in situ stress conditions using unconsolidated sandstone samples with varying grain compositions.The clogging phenomenon arises from the combined effects of grain migration and compaction,wherein the migration of both original and secondary crushed fine-grain particles blocks the seepage channels.Notably,grain composition influences the migration and transport properties of the grains.For samples composed of smaller grains,the apparent permeability demonstrates a transition from stability to decrease.In contrast,samples with larger grains experience a skip at the stability stage and directly enter the decrease stage,with a minor exception of a slight increase observed.Furthermore,a unique failure mode characterized by diameter shrinkage in the upper part of the sample is observed due to the combined effects of grain migration and in situ stress-induced compaction.These testing results contribute to a better understanding of the clogging mechanism caused by the coupled effects of grain migration and compaction during groundwater recharge in unconsolidated sandstone reservoirs used in groundwater-source heat pump systems.展开更多
The utilization of stone columns has emerged as a popular ground improvement strategy,whereas the drainage performance can be adversely hampered by clogging effect.Despite the ample progress of calculation methods for...The utilization of stone columns has emerged as a popular ground improvement strategy,whereas the drainage performance can be adversely hampered by clogging effect.Despite the ample progress of calculation methods for the consolidation of stone column-improved ground,theoretical investigations into the clogging effect have not been thoroughly explored.Furthermore,it is imperative to involve the column consolidation deformation to mitigate computational error on the consolidation of composite ground with high replacement ratios.In this context,an analytical model accounting for the initial clogging and coupled time and depth-dependent clogging of stone columns is established.Then,the resulting governing equations and analytical solutions are obtained under a new flow continuity relationship to incorporate column consolidation deformation.The accuracy and reliability of the proposed model are illustrated by degradation analysis and case studies with good agreements.Subsequently,the computed results of the current study are juxtaposed against the existing models,and an in-depth assessment of the impacts of several crucial parameters on the consolidation behavior is conducted.The results reveal that ignoring column consolidation deformation leads to an overestimate of the consolidation rate,with maximum error reaching up to 16%as the replacement ratio increases.Furthermore,the initial clogging also has a significant influence on the consolidation performance.Additionally,the increment of depth and time-clogging factors a and b will induce a noticeable retardation of the consolidation process,particularly in the later stage.展开更多
The silt soft soil in Nansha District of Guangzhou was the softest soft soil in China. It had the characteristics of high natural water content, high compressibility, long consolidation time, and complex layered distr...The silt soft soil in Nansha District of Guangzhou was the softest soft soil in China. It had the characteristics of high natural water content, high compressibility, long consolidation time, and complex layered distribution of soil layers. These characteristics formed the clogging characteristics of silt soft soil, which greatly increased the construction difficulty and hindered the construction progress. Therefore, based on the basic physical and mechanical properties of silt soft soil in Nansha District of Guangzhou, this paper evaluated the clogging characteristics of three silt soft soil areas in Nansha District of Guangzhou through long-term permeability test, and carried out scanning electron microscope test to explore the influence of different parameters and microstructure on the clogging difficulty of silt soft soil. The results showed that the silt soft soil Zone I and Zone II (shallow layer) in Nansha District of Guangzhou were divided into slight siltation levels, and the silt soft soil Zone III (deep layer) was mild siltation level. Large pores were widely distributed in shallow silt soft soil, while the continuity of large pores in deep silt soft soil was poor. The migration of fine particles that failed to establish contact with surrounding particles in the soil blocks the small pores of seepage and thus produces siltation.展开更多
With the completion of South-North Water Transfer Project in China, plenty of high quality water will be transported to Beijing. To restore the groundwater level in Beijing, part of transferred water is planned to be ...With the completion of South-North Water Transfer Project in China, plenty of high quality water will be transported to Beijing. To restore the groundwater level in Beijing, part of transferred water is planned to be used for artificial recharge. Clogging is an unavoidable challenge in the artificial recharge process. Therefore, a test is designed to analyse clogging duration and scope of influence and to test the reinjection properties of different recharge media. The test employs the self-designed sand column system with variable spacing and section monitoring, composed of four parts: Sand column, water-supply system, pressure-test system and flow-test system, to simulate the clogging of artificial recharge of sand and gravel pits. The hydraulic conductivity levels of all sand column sections are obtained to analyse the clogging of the injection of different concentrations in media of different particle sizes. In this experiment, two kinds of media are used–round gravel from sand and gravel pit in Xihuang village and the sand from sand and gravel pit by the Yongding River. The concentrations of recharge fluid are respectively 0.5 g/L and 1 g/L. The results show that clogging usually lasts for 20 hrs., and the hydraulic conductivity drops to the original 10%. Clogging usually occurs at 0–12 cm section of the sand column. The scope of influence is 0–60 cm. In column 3 and 4, whose average particle sizes are larger, section 20–50 cm also suffers from clogging, apart from section 0–12 cm. The effective recharge times are respectively 33 hrs. in column 1, 14 hrs. in column 2, 12 hrs. in column 3 and 12 hrs. in column 4. The larger the average particle size is, the quicker the clogging occurs. In media of larger particles, the change in suspension concentration does not have significant influence on the development of clogging. In conclusion, it is suggested that during artificial recharge, the conditions of reinjection medium should be fully considered and effective method of recharge be employed in order to improve effective recharge time.展开更多
[Objective] The aim was to al eviate the constructed wetland clogging problems and to explore to the effects of hydraulic loading on wetland clogging. [Method] The experiment, through artificial soil columns, simulate...[Objective] The aim was to al eviate the constructed wetland clogging problems and to explore to the effects of hydraulic loading on wetland clogging. [Method] The experiment, through artificial soil columns, simulated vertical flow arti-ficial wetland, set four hydraulic load level at 50, 100, 150 and 200 cm/d, to identify the impact of hydraulic loading on wetland clogging and to explore the factors run-ning threshold. [Result] The results show that the different levels of hydraulic loading have greater impact; in the constructed wetland clogging process under high hy-draulic loading of 200 cm/d, the effective life was only six months, and the single factor can be speculated that the threshold of the hydraulic load should be at 100-150 cm/d; system can last for six months at low hydraulic loading and last for three months at medium hydraulic load. [Conclusion] The research provides references for wetland clogging experiments in future.展开更多
Microfiltration membrane technology has been widely used in various industries for solid-liquid separation. However, pore clogging remains a persistent challenge. This study employs (CFD) and discrete element method (...Microfiltration membrane technology has been widely used in various industries for solid-liquid separation. However, pore clogging remains a persistent challenge. This study employs (CFD) and discrete element method (DEM) models to enhance our understanding of microfiltration membrane clogging. The models were validated by comparing them to experimental data, demonstrating reasonable consistency. Subsequently, a parametric study was conducted on a cross-flow model, exploring the influence of key parameters on clogging. Findings show that clogging is a complex phenomenon affected by various factors. The mean inlet velocity and transmembrane flux were found to directly impact clogging, while the confinement ratio and cosine of the membrane pore entrance angle had an inverse relationship with it. Two clog types were identified: internal (inside the pore) and external (arching at the pore entrance), with the confinement ratio determining the type. This study introduced a dimensionless number as a quantitative clogging indicator based on transmembrane flux, Reynolds number, filtration time, entrance angle cosine, and confinement ratio. While this hypothesis held true in simulations, future studies should explore variations in clogging indicators, and improved modeling of clogging characteristics. Calibration between numerical and physical times and consideration of particle volume fraction will enhance understanding.展开更多
Taking Zhuoyu reservoir in Shannan of Tibet as the test site,the authors collected soil samples for laboratory analysis,and devised infiltration-clogging equipment for laboratory test to research the effect of cloggin...Taking Zhuoyu reservoir in Shannan of Tibet as the test site,the authors collected soil samples for laboratory analysis,and devised infiltration-clogging equipment for laboratory test to research the effect of clogging process on permeability of loose dam foundation of plateau reservoir.Through laboratory test,the soil can cause clogging effect by itself,and the effect of clogging is relative to the water pressure.The clogging effect can be caused obviously by adding fine particles,and the clogging effect of the particles with 0.063-0.25 mm diameter is best,which verifies the rationality of the optimal diameter interval.It provides the realistic significance for the anti-seepage of the plateau reservoir dam foundation.展开更多
The accumulation of organic matter in substratum pores is regarded as an important factor causing clogging separately in the subsurface flow constructed wetlands.In this study,the developing process of clogging caused...The accumulation of organic matter in substratum pores is regarded as an important factor causing clogging separately in the subsurface flow constructed wetlands.In this study,the developing process of clogging caused by biofilm growth or organic particle accumulation instead of total organic matter accumulation was investigated in two groups of lab-scale vertical flow constructed wetlands（VFCWs）,which were fed with glucose（dissolved organic matter） and starch（particulate organic matter） influent.Results showed that the growth of biofilms within the substratum pores certainly caused remarkable reduction of effective porosity,especially for the strong organic wastewater,whereas its influence on infiltration rate was negligible.It was implied that the most important contribution of biofilm growth to clogging was accelerating the occurrence of clogging.In comparison with biofilm growth,particles accumulation within pores could rapidly reduce infiltration rate besides effective porosity and the clogging occurred in the upper 0-15 cm layer.With approximately equal amount of accumulated organic matter,the effective porosity of the clogged layer in starch-fed systems was far less than that of glucose-fed systems,which indicated that composition and accumulation mode in addition to the amount of the accumulated organic matter played an important role in causing clogging.展开更多
The nozzle clogging behavior of Ti-bearing IF steel was studied by metallographic analysis,scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS）,and X-ray diffraction（XRD）.According to the exper...The nozzle clogging behavior of Ti-bearing IF steel was studied by metallographic analysis,scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS）,and X-ray diffraction（XRD）.According to the experimental results,nozzle clogging primarily appears three layers.There are a lot of large-sized iron particles in the inner layer and mainly slag phase in the middle and outer layers.The principal clog constituents of the inner layer are loose alumina cluster inclusions and granular shaped alumina inclusions,containing iron particles. The clog constituents of the middle layer are mainly dendrite alumina inclusions.The primary phases existing in nozzle clogging are FeO·TiO2 and FeO·Al2O3 besidesα-Al2O3 and a-Fe.The FeO·TiO2 phases among the deposits adhere the deposits together firmly enough to lead to the inferior castability of Ti-bearing ultra low carbon steel compared with that of Ti-free low carbon Al-killed steel.展开更多
Chlorination has been recognized as an efficient and economically favorable method for treating clogging in drip emitters caused by biological growth during sewage application. Further important criteria for determini...Chlorination has been recognized as an efficient and economically favorable method for treating clogging in drip emitters caused by biological growth during sewage application. Further important criteria for determining an optimal chlorination scheme are the different responses of crops to the chloride added into the soil through chlorination. During two seasons in 2008 and 2009, field experiments were conducted in a solar-heated greenhouse with drip irrigation systems applying secondary sewage effluent to tomato plants to investigate the influences of chlorine injection intervals and levels on plant growth, yield, fruit quality, and emitter clogging. Injection intervals ranging from 2 to 8 wk and injection concentrations ranging 2-50 mg L-1 of free chlorine residual at the end of the laterals were used. For the 2008 experiments, the yield from the treatments of sewage application with chlorination was 7.5% lower than the yield from the treatment of sewage application without chlorination, while the yields for the treatments with and without chlorination were similar for the 2009 experiments. The statistical tests indicated that neither the chlorine injection intervals and concentrations nor the interactions between the two significantly influenced plant height, leaf area, or tomato yield for both years. The qualities of the fruit in response to chlorination were parameter-dependent. Chlorination did not significantly influence the quality of ascorbic acid, soluble sugar, or soluble acids, but the interaction between the chlorine injection interval and the chlorine concentration significantly influenced the levels of soluble solids. It was also confirmed that chlorination was an effective method for reducing biological clogging. These results suggested that chlorination is safe for a crop that has a moderate sensitivity to chlorine, like tomato, and can maintain a high level of performance in drip irrigation systems applying sewage effluent.展开更多
Shield tunneling is easily obstructed by clogging in clayey strata with small soil particles.However,soil clogging rarely occurs in strata with coarse-grained soils.Theoretically,a critical particle size of soils shou...Shield tunneling is easily obstructed by clogging in clayey strata with small soil particles.However,soil clogging rarely occurs in strata with coarse-grained soils.Theoretically,a critical particle size of soils should exist,below which there is a high risk of soil clogging in shield tunneling.To determine the critical particle size,a series of laboratory tests was carried out with a large-scale rotary shear apparatus to measure the tangential adhesion strength of soils with different particle sizes and water contents.It was found that the tangential adhesion strength at the soilesteel interface gradually increased linearly with applied normal pressure.When the particle size of the soil specimen was less than 0.15 mm,the interfacial adhesion force first increased and then decreased as the water content gradually increased;otherwise,the soil specimens did not manifest any interfacial adhesion force.The amount of soil mass adhering to the steel disc was positively correlated with the interfacial adhesion force,thus the interfacial adhesion force was adopted to characterize the soil clogging risk in shield tunneling.The critical particle size of soils causing clogging was determined to be 0.15 mm.Finally,the generation mechanism of interfacial adhesion force was explored for soils with different particle sizes to explain the critical particle size of soil with clogging risk in shield tunneling.展开更多
Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters.However,biofouling has been identified as a major contributor to emitter ...Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters.However,biofouling has been identified as a major contributor to emitter clogging in drip irrigation systems distributing reclaimed wastewater.Little is known about the biofilm structure and its influence on clogging in the drip emitter flow path.This study was first to investigate the microbial characteristics of mature biofilms present in the emitters and the effect of flow path structures on the biofilm microbial communities.The analysis of biofilm matrix structure using a scanning electron microscopy（SEM） revealed that particles in the matrix of the biofilm coupled extracellular polysaccharides（EPS） and formed sediment in the emitter flow path.Analysis of biofilm mass including protein,polysaccharide,and phospholipid fatty acids（PLFAs） showed that emitter flow path style influenced biofilm community structure and diversity.The correlations of biofilm biomass and discharge reduction after 360 h irrigation were computed and suggest that PFLAs provide the best correlation coeffcient.Comparatively,the emitter with the unsymmetrical dentate structure and shorter flow path（Emitter C） had the best anti-clogging capability.By optimizing the dentate structure,the internal flow pattern within the flow path could be enhanced as an important method to control the biofilm within emitter flow path.This study established electron microscope techniques and biochemical microbial analysis methods that may provide a framework for future emitter biofilm studies.展开更多
The type of inclusions in tundish steel and the formation mechanism of the submerged entry nozzle(SEN)clogging in the continuous casting of the rare earth(RE)high strength steel without calcium treatment were studied ...The type of inclusions in tundish steel and the formation mechanism of the submerged entry nozzle(SEN)clogging in the continuous casting of the rare earth(RE)high strength steel without calcium treatment were studied based on the plant trials and thermodynamic calculation.It was found that Ce_(2)O_(3) and CeAlO_(3) in tundish molten steel were transformed into Ce_(2)O_(2)S+CaO-Al_(2)O_(3) with the size of 2-3 lm during cooling.When the flow velocity of molten steel on surface of the SEN was slow due to the boundary layer effect,Ce_(2)O_(3) inclusion in molten steel reacted with Al_(2)O_(3) in the SEN refractory to form CeAlO3.With the continuous erosion of molten steel and reaction,the compositions of CeAlO_(3),Al_(2)O_(3) and CaO were aggregated,and the clogging layers with different zones were formed on surface of the SEN.Meanwhile,a small amount of molten steel remaining in the arc zone and corner zone of the SEN formed solidified steel.When calcium treatment is canceled,the reaction probability between inclusions in molten steel and refractory should be reduced by improving the material and shape of the SEN.展开更多
The influence of submerged entry nozzle clogging on the behavior of molten steel in continuously cast slab molds was studied using commercial code CFX4.3. The results indicate that clogging at the top part of the nozz...The influence of submerged entry nozzle clogging on the behavior of molten steel in continuously cast slab molds was studied using commercial code CFX4.3. The results indicate that clogging at the top part of the nozzle port not only increases the velocity of molten steel, but also enhances the wall shear stress, F number and heat flux. This clogging has the greatest effect on the behavior of molten steel. However, clogging at the top 1/3 of the nozzle only increases the velocity of molten steel and has little influence. Clogging at the bottom of the nozzle almost has no influence.展开更多
A nozzle clogging online forecasting model based on hydrodynamics engineering was developed, in which the actual flow rate was calculated from the mold width, thickness, and casting speed. There is a linear relationsh...A nozzle clogging online forecasting model based on hydrodynamics engineering was developed, in which the actual flow rate was calculated from the mold width, thickness, and casting speed. There is a linear relationship between the theoretical flow rate and the slide gate opening ratio as the molten steel level, argon flow rate, and the top slag weight are kept constant, and the relationship can be obtained by regression of the data collected at the beginning of the first heat in each casting sequence when the nozzle clogging does not occur. Then, during the casting, the theoretical flow rate can be calculated at intervals of one second. Comparing the theoretical flow rate with the actual flow rate, the online nozzle clogging ratio can be obtained at intervals of one second. The computer model based on the conception of the nozzle clogging ratio can display the degree of the nozzle clogging intuitively.展开更多
Aquifer recharge, which uses urban stormwater, is an effective technique to control the negative effects of groundwater overexploitation, while clogging problems in infiltration systems remain the key restricting fact...Aquifer recharge, which uses urban stormwater, is an effective technique to control the negative effects of groundwater overexploitation, while clogging problems in infiltration systems remain the key restricting factor in broadening its practice. Quantitative understanding of the clogging process is still very poor. A laboratory study was conducted to understand surface physical clogging processes, with the primary aim of developing a model for predicting suspended solid clogging processes before aquifer recharge projects start. The experiments investigated the clogging characteristics of different suspended solid sizes in recharge water by using a series of one-dimensional fine quartz sand columns. The results showed that the smaller the suspended particles in recharge water, the farther the distance of movement and the larger the scope of clogging in porous media. Clogging extents in fine sand were 1 cm, for suspended particle size ranging from 0.075 to 0.0385 mm, and 2 cm, for particles less than 0.0385 mm. In addition, clogging development occurred more rapidly for smaller suspended solid particles. It took 48, 42, and 36 hr respectively, for large-, medium-, and small-sized particles to reach pre-determined clogging standards. An empirical formula and iteration model for the surface clogging evolution process were derived. The verification results obtained from stormwater recharge into fine sand demonstrated that the model could reflect the real laws of the surface clogging process.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12365007 and 12265017)Yunnan Fundamental Research Projects(Grant Nos.202101AS070018 and 202101AV070015)+1 种基金the Scientific Research Foundation of the Yunnan Provincial Department of Education(Grant No.2023J1208)Xingdian Talents Support Program,and Yunnan Province Ten Thousand Talents Plan Young&Elite Talents Project,and Yunnan Province Computational Physics and Applied Science and Technology Innovation Team.The numerical simulation and significance estimation were performed on the Key Laboratory of High-Density Computing,Zhaotong University。
文摘Particle transport is a fundamental aspect of various systems,from artificial to biological.A common assumption is that particle motion follows Markovian(memoryless)processes in the absence of interaction between particles.However,hydrodynamic memory and the interaction between particles are ubiquitous,leaving many fundamental questions unanswered regarding transport of interacting particles involving hydrodynamic drag in corrugated channels,as described by the fractional Langevin equation.This study examines the hydrodynamic transport of interacting non-Brownian particles moving within a corrugated channel.We propose a method that relies on factors such as temperature,the driving force to alternate between no transport and finite net transport.Of importance is to note that the absence of transport results from the clogging,while the transport consists of collective motion and independent motion.The transport systems investigated in this work suggest the potential for sensor functionality within the system.Our findings may prove valuable for exploring the transport with hydrodynamic memory in various fields,including biology,physics,and chemistry.
基金National Natural Science Foundation of China(Nos.U21A20116,U21A20117 and 52304347)National Natural Science Foundation of Liaoning(Nos.2023-MSBA-135 and 2023-BSBA-107)+1 种基金the Fundamental Research Funds for the Central Universities(Nos.N2409006 and N2409008)are acknowledged to support this workSwedish Foundation for International Cooperation in Research and Higher Education(STINT,Project No.IB2022-9228)is acknowledged by W.Mu to support his visit between KTH(Sweden)and NEU(China).
文摘Understanding the motion behaviors of non-metallic inclusions in the liquid metal is important for clean steel production.High-temperature confocal laser scanning microscopy is applied to investigate the effect of different Ti and Al contents on the agglomeration behavior of non-metallic inclusions in low carbon steels.Furthermore,the agglomeration mechanism of inclusions was investigated through quantitative analysis of in-situ observation experiments and a modified Kralchevsky-Paunov model.The obtained results indicate that Al_(2)O_(3)is the main type inclusion in the low-alloys steels with both Al and Ti addition.This type of inclusion is more likely to absorb surrounding small-size inclusion particles,leading to a further growth for the cluster formation and contributing to a serious engineering problem,nozzle clogging.Besides,TiO_(x)is the main type inclusion in the molten steel with only Ti addition,and this type of inclusion is less likely to agglomerate and the individual inclusion particles show a‘free’motion with the fluid of molten steel.The difference between these two types of inclusions is due to the difference in attractive force and action distance at the meniscus created by the inclusion/steel/Ar multiple interfaces and influenced by the physical parameters,e.g.,contact angle and interface energy between inclusion and steel,and surface tension of the melt.
基金supported by the Fundamental Research Funds for the Central Universities(No.FRF-BD-23-01).
文摘Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.2023YJS053)the National Natural Science Foundation of China(Grant No.52278386).
文摘To fundamentally alleviate the excavation chamber clogging during slurry tunnel boring machine(TBM)advancing in hard rock,large-diameter short screw conveyor was adopted to slurry TBM of Qingdao Jiaozhou Bay Second Undersea Tunnel.To evaluate the discharging performance of short screw conveyor in different cases,the full-scale transient slurry-rock two-phase model for a short screw conveyor actively discharging rocks was established using computational fluid dynamics-discrete element method(CFD-DEM)coupling approach.In the fluid domain of coupling model,the sliding mesh technology was utilized to describe the rotations of the atmospheric composite cutterhead and the short screw conveyor.In the particle domain of coupling model,the dynamic particle factories were established to produce rock particles with the rotation of the cutterhead.And the accuracy and reliability of the CFD-DEM simulation results were validated via the field test and model test.Furthermore,a comprehensive parameter analysis was conducted to examine the effects of TBM operating parameters,the geometric design of screw conveyor and the size of rocks on the discharging performance of short screw conveyor.Accordingly,a reasonable rotational speed of screw conveyor was suggested and applied to Jiaozhou Bay Second Undersea Tunnel project.The findings in this paper could provide valuable references for addressing the excavation chamber clogging during ultra-large-diameter slurry TBM tunneling in hard rock for similar future.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFE0137200)National Natural Science Foundation of China(Grant Nos.52309147 and 52179114).
文摘In unconsolidated sandstone reservoirs,presence of numerous movable grains and a complex grain size composition necessitates a clear understanding of the physical clogging process for effective groundwater recharge in groundwater-source heat pump systems.To investigate this,a series of seepage experiments was conducted under in situ stress conditions using unconsolidated sandstone samples with varying grain compositions.The clogging phenomenon arises from the combined effects of grain migration and compaction,wherein the migration of both original and secondary crushed fine-grain particles blocks the seepage channels.Notably,grain composition influences the migration and transport properties of the grains.For samples composed of smaller grains,the apparent permeability demonstrates a transition from stability to decrease.In contrast,samples with larger grains experience a skip at the stability stage and directly enter the decrease stage,with a minor exception of a slight increase observed.Furthermore,a unique failure mode characterized by diameter shrinkage in the upper part of the sample is observed due to the combined effects of grain migration and in situ stress-induced compaction.These testing results contribute to a better understanding of the clogging mechanism caused by the coupled effects of grain migration and compaction during groundwater recharge in unconsolidated sandstone reservoirs used in groundwater-source heat pump systems.
基金funding support from the National Natural Science Foundation of China(Grant Nos.52178373 and 51878657).
文摘The utilization of stone columns has emerged as a popular ground improvement strategy,whereas the drainage performance can be adversely hampered by clogging effect.Despite the ample progress of calculation methods for the consolidation of stone column-improved ground,theoretical investigations into the clogging effect have not been thoroughly explored.Furthermore,it is imperative to involve the column consolidation deformation to mitigate computational error on the consolidation of composite ground with high replacement ratios.In this context,an analytical model accounting for the initial clogging and coupled time and depth-dependent clogging of stone columns is established.Then,the resulting governing equations and analytical solutions are obtained under a new flow continuity relationship to incorporate column consolidation deformation.The accuracy and reliability of the proposed model are illustrated by degradation analysis and case studies with good agreements.Subsequently,the computed results of the current study are juxtaposed against the existing models,and an in-depth assessment of the impacts of several crucial parameters on the consolidation behavior is conducted.The results reveal that ignoring column consolidation deformation leads to an overestimate of the consolidation rate,with maximum error reaching up to 16%as the replacement ratio increases.Furthermore,the initial clogging also has a significant influence on the consolidation performance.Additionally,the increment of depth and time-clogging factors a and b will induce a noticeable retardation of the consolidation process,particularly in the later stage.
文摘The silt soft soil in Nansha District of Guangzhou was the softest soft soil in China. It had the characteristics of high natural water content, high compressibility, long consolidation time, and complex layered distribution of soil layers. These characteristics formed the clogging characteristics of silt soft soil, which greatly increased the construction difficulty and hindered the construction progress. Therefore, based on the basic physical and mechanical properties of silt soft soil in Nansha District of Guangzhou, this paper evaluated the clogging characteristics of three silt soft soil areas in Nansha District of Guangzhou through long-term permeability test, and carried out scanning electron microscope test to explore the influence of different parameters and microstructure on the clogging difficulty of silt soft soil. The results showed that the silt soft soil Zone I and Zone II (shallow layer) in Nansha District of Guangzhou were divided into slight siltation levels, and the silt soft soil Zone III (deep layer) was mild siltation level. Large pores were widely distributed in shallow silt soft soil, while the continuity of large pores in deep silt soft soil was poor. The migration of fine particles that failed to establish contact with surrounding particles in the soil blocks the small pores of seepage and thus produces siltation.
基金supported by public welfare geological investigation and scientific project of Beijing (2010): The key technology on clogging features analysis of groundwater artificial recharge
文摘With the completion of South-North Water Transfer Project in China, plenty of high quality water will be transported to Beijing. To restore the groundwater level in Beijing, part of transferred water is planned to be used for artificial recharge. Clogging is an unavoidable challenge in the artificial recharge process. Therefore, a test is designed to analyse clogging duration and scope of influence and to test the reinjection properties of different recharge media. The test employs the self-designed sand column system with variable spacing and section monitoring, composed of four parts: Sand column, water-supply system, pressure-test system and flow-test system, to simulate the clogging of artificial recharge of sand and gravel pits. The hydraulic conductivity levels of all sand column sections are obtained to analyse the clogging of the injection of different concentrations in media of different particle sizes. In this experiment, two kinds of media are used–round gravel from sand and gravel pit in Xihuang village and the sand from sand and gravel pit by the Yongding River. The concentrations of recharge fluid are respectively 0.5 g/L and 1 g/L. The results show that clogging usually lasts for 20 hrs., and the hydraulic conductivity drops to the original 10%. Clogging usually occurs at 0–12 cm section of the sand column. The scope of influence is 0–60 cm. In column 3 and 4, whose average particle sizes are larger, section 20–50 cm also suffers from clogging, apart from section 0–12 cm. The effective recharge times are respectively 33 hrs. in column 1, 14 hrs. in column 2, 12 hrs. in column 3 and 12 hrs. in column 4. The larger the average particle size is, the quicker the clogging occurs. In media of larger particles, the change in suspension concentration does not have significant influence on the development of clogging. In conclusion, it is suggested that during artificial recharge, the conditions of reinjection medium should be fully considered and effective method of recharge be employed in order to improve effective recharge time.
基金Supported by National Natural Science Foundation of China(41071214)~~
文摘[Objective] The aim was to al eviate the constructed wetland clogging problems and to explore to the effects of hydraulic loading on wetland clogging. [Method] The experiment, through artificial soil columns, simulated vertical flow arti-ficial wetland, set four hydraulic load level at 50, 100, 150 and 200 cm/d, to identify the impact of hydraulic loading on wetland clogging and to explore the factors run-ning threshold. [Result] The results show that the different levels of hydraulic loading have greater impact; in the constructed wetland clogging process under high hy-draulic loading of 200 cm/d, the effective life was only six months, and the single factor can be speculated that the threshold of the hydraulic load should be at 100-150 cm/d; system can last for six months at low hydraulic loading and last for three months at medium hydraulic load. [Conclusion] The research provides references for wetland clogging experiments in future.
文摘Microfiltration membrane technology has been widely used in various industries for solid-liquid separation. However, pore clogging remains a persistent challenge. This study employs (CFD) and discrete element method (DEM) models to enhance our understanding of microfiltration membrane clogging. The models were validated by comparing them to experimental data, demonstrating reasonable consistency. Subsequently, a parametric study was conducted on a cross-flow model, exploring the influence of key parameters on clogging. Findings show that clogging is a complex phenomenon affected by various factors. The mean inlet velocity and transmembrane flux were found to directly impact clogging, while the confinement ratio and cosine of the membrane pore entrance angle had an inverse relationship with it. Two clog types were identified: internal (inside the pore) and external (arching at the pore entrance), with the confinement ratio determining the type. This study introduced a dimensionless number as a quantitative clogging indicator based on transmembrane flux, Reynolds number, filtration time, entrance angle cosine, and confinement ratio. While this hypothesis held true in simulations, future studies should explore variations in clogging indicators, and improved modeling of clogging characteristics. Calibration between numerical and physical times and consideration of particle volume fraction will enhance understanding.
基金Supported by Project of the National Natural Science Foundation of China(No.41072197)
文摘Taking Zhuoyu reservoir in Shannan of Tibet as the test site,the authors collected soil samples for laboratory analysis,and devised infiltration-clogging equipment for laboratory test to research the effect of clogging process on permeability of loose dam foundation of plateau reservoir.Through laboratory test,the soil can cause clogging effect by itself,and the effect of clogging is relative to the water pressure.The clogging effect can be caused obviously by adding fine particles,and the clogging effect of the particles with 0.063-0.25 mm diameter is best,which verifies the rationality of the optimal diameter interval.It provides the realistic significance for the anti-seepage of the plateau reservoir dam foundation.
基金supported by the Natural Science Foundation of Jiangsu Province (No.BK2006710)
文摘The accumulation of organic matter in substratum pores is regarded as an important factor causing clogging separately in the subsurface flow constructed wetlands.In this study,the developing process of clogging caused by biofilm growth or organic particle accumulation instead of total organic matter accumulation was investigated in two groups of lab-scale vertical flow constructed wetlands（VFCWs）,which were fed with glucose（dissolved organic matter） and starch（particulate organic matter） influent.Results showed that the growth of biofilms within the substratum pores certainly caused remarkable reduction of effective porosity,especially for the strong organic wastewater,whereas its influence on infiltration rate was negligible.It was implied that the most important contribution of biofilm growth to clogging was accelerating the occurrence of clogging.In comparison with biofilm growth,particles accumulation within pores could rapidly reduce infiltration rate besides effective porosity and the clogging occurred in the upper 0-15 cm layer.With approximately equal amount of accumulated organic matter,the effective porosity of the clogged layer in starch-fed systems was far less than that of glucose-fed systems,which indicated that composition and accumulation mode in addition to the amount of the accumulated organic matter played an important role in causing clogging.
基金supported by the National Key Technologies R&D Program of China(No.2006BAE03A06)
文摘The nozzle clogging behavior of Ti-bearing IF steel was studied by metallographic analysis,scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS）,and X-ray diffraction（XRD）.According to the experimental results,nozzle clogging primarily appears three layers.There are a lot of large-sized iron particles in the inner layer and mainly slag phase in the middle and outer layers.The principal clog constituents of the inner layer are loose alumina cluster inclusions and granular shaped alumina inclusions,containing iron particles. The clog constituents of the middle layer are mainly dendrite alumina inclusions.The primary phases existing in nozzle clogging are FeO·TiO2 and FeO·Al2O3 besidesα-Al2O3 and a-Fe.The FeO·TiO2 phases among the deposits adhere the deposits together firmly enough to lead to the inferior castability of Ti-bearing ultra low carbon steel compared with that of Ti-free low carbon Al-killed steel.
基金financially supported by the National Natural Science Foundation of China (50779078)
文摘Chlorination has been recognized as an efficient and economically favorable method for treating clogging in drip emitters caused by biological growth during sewage application. Further important criteria for determining an optimal chlorination scheme are the different responses of crops to the chloride added into the soil through chlorination. During two seasons in 2008 and 2009, field experiments were conducted in a solar-heated greenhouse with drip irrigation systems applying secondary sewage effluent to tomato plants to investigate the influences of chlorine injection intervals and levels on plant growth, yield, fruit quality, and emitter clogging. Injection intervals ranging from 2 to 8 wk and injection concentrations ranging 2-50 mg L-1 of free chlorine residual at the end of the laterals were used. For the 2008 experiments, the yield from the treatments of sewage application with chlorination was 7.5% lower than the yield from the treatment of sewage application without chlorination, while the yields for the treatments with and without chlorination were similar for the 2009 experiments. The statistical tests indicated that neither the chlorine injection intervals and concentrations nor the interactions between the two significantly influenced plant height, leaf area, or tomato yield for both years. The qualities of the fruit in response to chlorination were parameter-dependent. Chlorination did not significantly influence the quality of ascorbic acid, soluble sugar, or soluble acids, but the interaction between the chlorine injection interval and the chlorine concentration significantly influenced the levels of soluble solids. It was also confirmed that chlorination was an effective method for reducing biological clogging. These results suggested that chlorination is safe for a crop that has a moderate sensitivity to chlorine, like tomato, and can maintain a high level of performance in drip irrigation systems applying sewage effluent.
基金The financial support from the National Natural Science Foun-dation of China(Grant Nos.52022112 and 51778637)the Sci-ence and Technology Innovation Program of Hunan Province(Grant No.2021RC3015)are acknowledged and appreciated.
文摘Shield tunneling is easily obstructed by clogging in clayey strata with small soil particles.However,soil clogging rarely occurs in strata with coarse-grained soils.Theoretically,a critical particle size of soils should exist,below which there is a high risk of soil clogging in shield tunneling.To determine the critical particle size,a series of laboratory tests was carried out with a large-scale rotary shear apparatus to measure the tangential adhesion strength of soils with different particle sizes and water contents.It was found that the tangential adhesion strength at the soilesteel interface gradually increased linearly with applied normal pressure.When the particle size of the soil specimen was less than 0.15 mm,the interfacial adhesion force first increased and then decreased as the water content gradually increased;otherwise,the soil specimens did not manifest any interfacial adhesion force.The amount of soil mass adhering to the steel disc was positively correlated with the interfacial adhesion force,thus the interfacial adhesion force was adopted to characterize the soil clogging risk in shield tunneling.The critical particle size of soils causing clogging was determined to be 0.15 mm.Finally,the generation mechanism of interfacial adhesion force was explored for soils with different particle sizes to explain the critical particle size of soil with clogging risk in shield tunneling.
基金supported by the National Natural Science Foundation of China (No.50379053,50609029,50779068)
文摘Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters.However,biofouling has been identified as a major contributor to emitter clogging in drip irrigation systems distributing reclaimed wastewater.Little is known about the biofilm structure and its influence on clogging in the drip emitter flow path.This study was first to investigate the microbial characteristics of mature biofilms present in the emitters and the effect of flow path structures on the biofilm microbial communities.The analysis of biofilm matrix structure using a scanning electron microscopy（SEM） revealed that particles in the matrix of the biofilm coupled extracellular polysaccharides（EPS） and formed sediment in the emitter flow path.Analysis of biofilm mass including protein,polysaccharide,and phospholipid fatty acids（PLFAs） showed that emitter flow path style influenced biofilm community structure and diversity.The correlations of biofilm biomass and discharge reduction after 360 h irrigation were computed and suggest that PFLAs provide the best correlation coeffcient.Comparatively,the emitter with the unsymmetrical dentate structure and shorter flow path（Emitter C） had the best anti-clogging capability.By optimizing the dentate structure,the internal flow pattern within the flow path could be enhanced as an important method to control the biofilm within emitter flow path.This study established electron microscope techniques and biochemical microbial analysis methods that may provide a framework for future emitter biofilm studies.
基金the financial support of the Natural Science Foundation of Inner Mongolia Autonomous Region of China(No.2020MS0517)Science and Technology Project of Inner Mongolia Autonomous Region of China(No.2020GG0109).
文摘The type of inclusions in tundish steel and the formation mechanism of the submerged entry nozzle(SEN)clogging in the continuous casting of the rare earth(RE)high strength steel without calcium treatment were studied based on the plant trials and thermodynamic calculation.It was found that Ce_(2)O_(3) and CeAlO_(3) in tundish molten steel were transformed into Ce_(2)O_(2)S+CaO-Al_(2)O_(3) with the size of 2-3 lm during cooling.When the flow velocity of molten steel on surface of the SEN was slow due to the boundary layer effect,Ce_(2)O_(3) inclusion in molten steel reacted with Al_(2)O_(3) in the SEN refractory to form CeAlO3.With the continuous erosion of molten steel and reaction,the compositions of CeAlO_(3),Al_(2)O_(3) and CaO were aggregated,and the clogging layers with different zones were formed on surface of the SEN.Meanwhile,a small amount of molten steel remaining in the arc zone and corner zone of the SEN formed solidified steel.When calcium treatment is canceled,the reaction probability between inclusions in molten steel and refractory should be reduced by improving the material and shape of the SEN.
文摘The influence of submerged entry nozzle clogging on the behavior of molten steel in continuously cast slab molds was studied using commercial code CFX4.3. The results indicate that clogging at the top part of the nozzle port not only increases the velocity of molten steel, but also enhances the wall shear stress, F number and heat flux. This clogging has the greatest effect on the behavior of molten steel. However, clogging at the top 1/3 of the nozzle only increases the velocity of molten steel and has little influence. Clogging at the bottom of the nozzle almost has no influence.
基金financially supported by the State EconomicTrade Commission of China (No.OIBK-098-02-07)
文摘A nozzle clogging online forecasting model based on hydrodynamics engineering was developed, in which the actual flow rate was calculated from the mold width, thickness, and casting speed. There is a linear relationship between the theoretical flow rate and the slide gate opening ratio as the molten steel level, argon flow rate, and the top slag weight are kept constant, and the relationship can be obtained by regression of the data collected at the beginning of the first heat in each casting sequence when the nozzle clogging does not occur. Then, during the casting, the theoretical flow rate can be calculated at intervals of one second. Comparing the theoretical flow rate with the actual flow rate, the online nozzle clogging ratio can be obtained at intervals of one second. The computer model based on the conception of the nozzle clogging ratio can display the degree of the nozzle clogging intuitively.
基金supported by the National Natural Science Foundation of China (No. 40902068,41002077)the Science Frontiers and Innovation of Interdisciplinary of Jilin University,China (No. 201103112)
文摘Aquifer recharge, which uses urban stormwater, is an effective technique to control the negative effects of groundwater overexploitation, while clogging problems in infiltration systems remain the key restricting factor in broadening its practice. Quantitative understanding of the clogging process is still very poor. A laboratory study was conducted to understand surface physical clogging processes, with the primary aim of developing a model for predicting suspended solid clogging processes before aquifer recharge projects start. The experiments investigated the clogging characteristics of different suspended solid sizes in recharge water by using a series of one-dimensional fine quartz sand columns. The results showed that the smaller the suspended particles in recharge water, the farther the distance of movement and the larger the scope of clogging in porous media. Clogging extents in fine sand were 1 cm, for suspended particle size ranging from 0.075 to 0.0385 mm, and 2 cm, for particles less than 0.0385 mm. In addition, clogging development occurred more rapidly for smaller suspended solid particles. It took 48, 42, and 36 hr respectively, for large-, medium-, and small-sized particles to reach pre-determined clogging standards. An empirical formula and iteration model for the surface clogging evolution process were derived. The verification results obtained from stormwater recharge into fine sand demonstrated that the model could reflect the real laws of the surface clogging process.
