Groundwater inrush is a hazard that always occurs during underground mining.Grouting is one of the most effective processes to seal underground water inflow for hazard prevention.In this study,grouting experiments are...Groundwater inrush is a hazard that always occurs during underground mining.Grouting is one of the most effective processes to seal underground water inflow for hazard prevention.In this study,grouting experiments are conducted by using a visualized transparent single-fracture replica with plane roughness.Image processing and analysis are performed to investigate the thermo–hydro–mechanical coupling effect on the grouting diffusion under coal mine flowing water conditions.The results show that higher ambient temperature leads to shorter initial gel time of chemical grout and leads to a better relative sealing efficiency in the case of a lower flow rate.However,with a higher water flow rate,the relative sealing efficiency is gradually reduced under higher temperature conditions.The grouting pressure,the seepage pressure,and the temperature are measured.The results reveal that the seepage pressure shows a positive correlation with the grouting pressure,while the temperature change shows a negative correlation with the seepage pressure and the grouting pressure.The“equivalent grouting point offset”effect of grouting shows an eccentric elliptical diffusion with larger grouting distance and width under lower temperature conditions.展开更多
By introducing virtual water(VW)flow correlation coefficients and risk indicators,this study examines the VW transmission relationship between urban agglomerations and cities in the Yellow River Basin(YRB)and its impa...By introducing virtual water(VW)flow correlation coefficients and risk indicators,this study examines the VW transmission relationship between urban agglomerations and cities in the Yellow River Basin(YRB)and its impact on regional water resources pressure.The results show that:except for the Shandong Peninsula Urban Agglomeration(SPUA)and Central Plains Urban Agglomeration(CPUA),the other urban agglomerations primarily act as VW exporting regions,while virtual water-importing cities are concentrated in the eastern regions.Notably,the Ningxia Urban Agglomeration(NUA)demonstrates significantly higher VW impact and sensitivity coefficients values than the remaining six urban agglomerations.First-tier cities generally display lower virtual water impact and sensitivity coefficients,whereas emerging cities exhibit the opposite trend.Additionally,we observe uneven risk variations between VW importing and exporting regions.Taking NUA as an example,the risk increase resulting from VW exports significantly exceeds the risk reduction associated with VW imports in the corresponding regions.It’s important to highlight that first-tier cities consistently decrease water resource risk through VW imports in the study years.However,among second and third-tier cities,only 38.9%experience reduced water resource risk through VW imports.Therefore,we recommend a focused examination of VW imports and exports in western region urban agglomerations,cities,and second and third-tier cities within the watershed.Leveraging virtual water’s asymmetric and high-value transfer can alleviate water resource pressure and scarcity risks in high-pressure regions by shifting them to lower-pressure regions,thus mitigating water resource stress across regions.展开更多
As intelligent sensors for marine applications rapidly advance,there is a growing emphasis on developing efficient,low-cost,and sustainable power sources to enhance their performance.With the continuous development of...As intelligent sensors for marine applications rapidly advance,there is a growing emphasis on developing efficient,low-cost,and sustainable power sources to enhance their performance.With the continuous development of triboelectric nanogenerators(TENGs),known for their simple structure and versatile operational modes,these devices exhibit promising technological potential and have garnered extensive attention from a broad spectrum of researchers.The single-electrode mode of TENGs presents an effective means to harness eco-friendly energy sourced from flowing water.In this study,the factors affecting the output performance were investigated using different structures of single-electrode solid-liquid TENGs placed in a circulating water tank.In addition,the solid‒liquid contact process was numerically simulated using the COMSOL Multiphysics software,and significant potential energy changes were obtained for the solid‒liquid contact and liquid flow processes.Finally,the energy generated is collected and converted to power several light-emitting diodes,demonstrating that solid‒liquid TENGs can generate effective electrical power in a flowing water environment.Through several experimental investigations,we finally determined that the flow rate of the liquid,the thickness of the friction electrode material,and the contact area have the most significant effect on the output efficiency of TENGs in the form of flowing water,which provides a guide for improving their performance in the future.展开更多
The icing of areo-engine inlet components during flight can affect engine operational safety.Conventional hot-air anti-icing systems require a large amount of bleed air,which compromises engine performance.Consequentl...The icing of areo-engine inlet components during flight can affect engine operational safety.Conventional hot-air anti-icing systems require a large amount of bleed air,which compromises engine performance.Consequently,low-energy anti/de-icing methods based on superhydrophobic surfaces have attracted widespread attention.Previous studies have demonstrated that for stationary components,superhydrophobic surfaces can significantly reduce anti-icing energy consumption by altering the flow behavior of runback water.However,for rotating inlet components of aero-engines,the effectiveness of superhydrophobic surfaces and the influence of surface wettability on the evolution of runback water flow remain unclear due to the effects of centrifugal and Coriolis forces.This study establishes a 3D liquid water flow simulation model using the volume of fluid(VOF)method to investigate the effects of rotational speed,airflow velocity,and surface wettability on the runback water flow behavior over the rotating spinner under dynamic rotation conditions.The results show that the rotational effects and surface wettability mutually reinforce one another.Specifically,increasing the rotational speed and contact angle can both enhance the flow velocity of liquid water and accelerate the breakup and rupture of liquid film,leading to the formation of rivulets,droplets,and subsequent detachment from the surface.A theoretical model based on force balance is proposed to describe the evolution of runback water flow,and the analysis reveals that as the rotational speed and contact angle increase,the water film is more likely to break up to form rivulets and beads,and the critical radius for droplet detachment from the surface decreases,making it easier removal from the surface.展开更多
The existing deep-sea sediment plume tests are mostly under small-scale static water and rarely under large-scale flowing water conditions.In this study,large-scale tank experiments of flowing water were designed and ...The existing deep-sea sediment plume tests are mostly under small-scale static water and rarely under large-scale flowing water conditions.In this study,large-scale tank experiments of flowing water were designed and conducted to investigate the morphological characteristics and concentration evolution of the sediment plumes under different discharge rates(Q)and initial sediment concentrations(c).Viscosity tests,resuspension tests and free settling tests of the sediment solution with different c values were performed to reveal the settling mechanism of the plume diffusion process.The results show that the plume diffusion morphology variation in flowing water has four stages and the plume concentration evolution has three stages.The larger the Q,the smaller the initial incidence angle at the discharge outlet,the larger the diffusion range,the poorer the stability and the more complicated the diffusion morphology.The larger the c,the larger the settling velocity,the faster the formation of high-concentration accumulation zone,the better the stability and the clearer the diffusion boundary.The research results could provide experimental data for assessing the impact of deep-sea mining on the ocean environment.展开更多
The equilibrium between the supply and demand of water purification services is essential for safeguarding watershed ecosystems and supporting sustainable socio-economic growth.While current research mainly emphasizes...The equilibrium between the supply and demand of water purification services is essential for safeguarding watershed ecosystems and supporting sustainable socio-economic growth.While current research mainly emphasizes the static analysis of this balance,dynamic investigations into service flow characteristics remain scarce.This study focuses on the Xiangjiang River Basin in southern China,utilizing the InVEST model,differential equations governing supply and demand,and social network analysis to investigate the spatio-temporal patterns of water purification service supply and demand.The results reveal that between 2000 and 2020,the supply of water purification services showed a slight upward trend,while demand exhibited a fluctuating downward tendency,and the supply-demand surplus fluctuated.On an annual basis,the supply generally met the demand,but significant spatial variation in supply-demand balance was observed,with high-risk zones concentrated in the central Hengshao arid corridor and the northern Changzhutan metropolitan area.In the water purification service network,surplus nodes increased,while deficit nodes decreased over time.Network density improved from 98.96%in 2000 to 100%in 2020.The flow of surplus services from upstream regions alleviated supply-demand imbalances downstream,notably in the Hengyang-Shaoyang(Hengshao)arid corridor and the Changsha-Zhuzhou-Xiangtan(Changzhutan)metropolitan area.However,during drought years,diminished water volume intensified supply-demand pressures in these regions.This research framework,which incorporates the dynamic effects of service flow,broadens the scope of water purification service studies and provides a solid foundation for integrated water resource and environmental management.展开更多
Three tracing tests from the same injection point executed at low, medium, and high water levels in the karst aquifer near Tianshengan village, Lunan Stone Forest, Yunnan Province, China, have revealed the basic prope...Three tracing tests from the same injection point executed at low, medium, and high water levels in the karst aquifer near Tianshengan village, Lunan Stone Forest, Yunnan Province, China, have revealed the basic properties of underground water flow. They showed the general directions of water flows; tracer concentrations were observed at six successive points allowing for the calculation of apparent dominant flow velocities at these sections towards the Dalongtan karst spring. For the high water level, the discharge between single sections was between two and 10 times greater than that at low water level. For the medium water level, the flow velocity at different sections was between 1.4 and 3.7 times faster than that at low water level; and for high water level, it was between 1.3 and 2.7 times faster than that at medium water level. The fastest water flow appeared at the first section （23 cm/s at medium water level）; and the slowest （0.6 cm/s at low water level） appeared where water flow must cross the Tianshengan fault （north-south direction）, and later, a layer of 20-30 m thickness of quartz sandstone and shale clay-stones. It was also possible to calculate the recovery of the tracer for point 4, Dakenyan, where discharge was measured. At the medium water level, 50% of the injected tracer was detected a half-day after its first appearance and at low water level after more than 3 days. The previously published research illustrates the transport velocities of possible contaminants and their solubilities in water at different hydrological conditions.展开更多
Global climate change and increased human consumption have aggravated the uneven spatiotemporal distribution of watershed water resources, affecting the water provision supply and demand state. However, this problem h...Global climate change and increased human consumption have aggravated the uneven spatiotemporal distribution of watershed water resources, affecting the water provision supply and demand state. However, this problem has often been ignored. The present study used the Xiangjiang River basin(XRB) as the study area, and the Integrated Valuation of Ecosystem Services and Trade-offs(InVEST) model, demand quantification model,supply–demand ratio, and water flow formula were applied to explore the spatial heterogeneity, flow, and equilibrium between water supply and demand. The results demonstrated significant spatial heterogeneity in the upstream, midstream, and downstream regions.The areas of water shortage were mainly located the downstream of the Changsha–Zhuzhou–Xiangtan urban agglomeration, and the Hengyang basin was the most scarcity area. Affected by terrain gradients and human needs, water flow varied from-16.33 × 10^(8) m^(3) to 13.69 × 10^(8) m^(3)from the upstream to the downstream area, which provided a possibility to reduce spatial heterogeneity. In the future, measures such as strengthening water resource system control,sponge city construction, and dynamic monitoring technology should be taken to balance the supply and demand of water in different river sections of the basin. This study can provide references for regulating water resources allocation in different reaches of the basin.展开更多
To deal with the moving boundary hydrodynamic problems of the tidal flats in shallow water flow models, a new wetting and drying （WD） method is proposed. In the new method, a ＂predicted water depth＂ is evaluated e...To deal with the moving boundary hydrodynamic problems of the tidal flats in shallow water flow models, a new wetting and drying （WD） method is proposed. In the new method, a ＂predicted water depth＂ is evaluated explicitly based on the simplified shallow water equations and used to determine the status （wet or dry） together with the direction of flow. Compared with previous WD method, besides the water elevation, more factors, such as the flow velocity and the surface shear stress, are taken into account in the new method to determine the moving boundary. In addition, a formula is deduced to determine the threshold, as critical water depth, which needs to be preset before simulations. The new WD method is tested with five cases including three 1D ones and two 2D ones. The results show that the new WD method can simulate the wetting and drying process, in beth typical and practical cases, with smooth manner and achieves effective estimation of the retention volume at shallow water body.展开更多
Based on a typical multi-arch tunnel in a freeway, the fast Lagrangian analysis of continua in 3 dimensions(FLAC3D) was used to calculate the surrounding rock deformation of the tunnel under which the effect of underg...Based on a typical multi-arch tunnel in a freeway, the fast Lagrangian analysis of continua in 3 dimensions(FLAC3D) was used to calculate the surrounding rock deformation of the tunnel under which the effect of underground water seepage flow was taken into account or not. The distribution of displacement field around the multi-arch tunnel, which is influenced by the seepage field, was gained. The result indicates that the settlement values of the vault derived from coupling analysis are bigger when considering the seepage flow effect than that not considering. Through the contrast of arch subsidence quantities calculated by two kinds of computation situations, and the comparison between the calculated and measured value of tunnel vault settlement, it is found that the calculated value(5.7-6.0 mm) derived from considering the seepage effect is more close to the measured value(5.8-6.8 mm). Therefore, it is quite necessary to consider the seepage flow effect of the underground water in aquiferous stratum for multi-arch tunnel design.展开更多
A physical model test has been conducted to study the oil diffusion from the submarine pipeline under water flow.The crude oil in the flume is spilled from a leakage point of the pipeline and diffused from the seabed ...A physical model test has been conducted to study the oil diffusion from the submarine pipeline under water flow.The crude oil in the flume is spilled from a leakage point of the pipeline and diffused from the seabed to the surface. By the non-contact optical measuring technology, an image acquisition and data analysis system is designed to explore the spilled mechanism and characteristic. The oil trajectory, velocity and the rising time to the surface are obtained through this system. The influence of the water flow and the spilled discharge on the behavior of the spilled oil are analyzed from both qualitative and quantitative perspectives. The sensitivity study of the characteristic physical quantities to various factors are presented afterward. The spilled oil under water is mainly distributed in the form of the scattered particles with different sizes. The rising process of the oil can be divided into three stages: full, dispersion and aggregation period. The spilled discharge is the primary factor affecting the rising time of the oil particles. In the rising process of the oil particles, the vertical velocity of the oil is mainly affected by the spilled discharge, and the transverse velocity is more dependent on the water velocity. The deviation of the transverse oil velocity is much larger than that of the rising time and the vertical oil velocity. The study can provide a theoretical reference for the prediction system of oil spill emergency.展开更多
Temperature and water flow through a culvert beneath the Alaska Highway near Beaver Creek,Yukon,were measured at hourly intervals between June and October 2013.These data were used to simulate the effect of the culver...Temperature and water flow through a culvert beneath the Alaska Highway near Beaver Creek,Yukon,were measured at hourly intervals between June and October 2013.These data were used to simulate the effect of the culvert on the thermal regime of the road embankment and subjacent permafrost.A 2-D thermal model of the embankment and permafrost was developed with TEMP/W and calibrated using field observations.Empirical relations were obtained between water temperatures at the entrance to the culvert,flow into the culvert,and water temperatures inside the structure.Water temperatures at the entrance and inside the culvert had a linear relation,while water temperatures inside the culvert and water flow were associated by a logarithmic relation.A multiple linear regression was used to summarize these relations.From this relationship,changes in the flow rate and water temperatures at the entrance of the culvert were simulated to obtain predicted water temperatures in the culvert.The temperatures in the culvert were used in the thermal model to determine their effects on the ground thermal regime near the culvert.Variation of ±10% in water flow rate had no impact on the thermal regime underneath the culvert.Variation of water temperature at the entrance of the culvert had a noticeable influence on the thermal regime.A final simulation was conducted without insulation beneath the culvert.The thaw depth was 30 cm with insulation,and 120 cm without insulation,illustrating the importance of insulation to the ground thermal regime.展开更多
This paper presents the characteristics of a double helix capacitance sensor for measurement of the liquid holdup in horizontal oil–water two-phase flow. The finite element method is used to calculate the sensitivity...This paper presents the characteristics of a double helix capacitance sensor for measurement of the liquid holdup in horizontal oil–water two-phase flow. The finite element method is used to calculate the sensitivity field of the sensor in a pipe with 20 mm inner diameter and the effect of sensor geometry on the distribution of sensitivity field is presented. Then, a horizontal oil–water two-phase flow experiment is carried out to measure the response of the double helix capacitance sensor, in which a novel method is proposed to calibrate the liquid holdup based on three pairs of parallel-wire capacitance probes. The performance of the sensor is analyzed in terms of the flow structures detected by mini-conductance array probes.展开更多
A particular porosity method named ＂slot method＂ is implemented in a depth-integrated shallow water flow model （DIVAST） to simulate wetting and drying processes. Discussed is the relationship between the shape fac...A particular porosity method named ＂slot method＂ is implemented in a depth-integrated shallow water flow model （DIVAST） to simulate wetting and drying processes. Discussed is the relationship between the shape factors of the ＂slot＂ and the preset depth used in ＂wetting-drying＂ algorithm. Two typical tests are conducted to examine the performance of the method with the effect of the shape factors of the ＂slot＂ being checked in detail in the first test. Numerical results demonstrate that： 1 ） no additional effort to improve the finite difference scheme is needed to implement ＂slot method＂ in DIVAST, and 2） ＂slot method＂ will simulate wetting and diying processes correctly if the shape factors of the ＂slot＂ being selected properly.展开更多
We present a series of experimental tests on chemical grouting into a fracture with flowing and static water,using a transparent fracture grouting experimental device.Variations of seepage pressure and grout propagati...We present a series of experimental tests on chemical grouting into a fracture with flowing and static water,using a transparent fracture grouting experimental device.Variations of seepage pressure and grout propagation were compared in our investigation.The results show that flowing water results in drops of seepage pressure,development of penetration radii in the upstream side and drops of propagation area during the same period,compared with grouting in static water.The propagation area in static water is always round before grouts reach the joint boundaries.However,the propagation shape changes from round to an elliptic shape for grouting into a fracture with flowing water.A theoretical model for the grout penetration radius in a fracture considering flowing velocity was developed and validated by our experimental results.These results are helpful in improving understanding of fracture grouting mechanism and in guiding engineering practices.展开更多
In the absorption chamber of a high-energy laser energy meter, water is directly used as an absorbing medium and the interaction of the high-power laser and the water flow can produce a variety of physical phenomena s...In the absorption chamber of a high-energy laser energy meter, water is directly used as an absorbing medium and the interaction of the high-power laser and the water flow can produce a variety of physical phenomena such as phase transitions. The unit difference method is adopted to deduce the phase transition model for water flow irradiated by a high-energy laser. In addition, the model is simulated and verified through experiments. Among them, the experimental verification uses the photographic method, shooting the distribution and the form of the air mass of water flow in different operating conditions, which are compared with the simulation results. The research shows that it is achievable to reduce the intensity of the phase transition by increasing the water flow, reducing the power intensity of the beam, shortening the distance the beam covers, reducing the initial water temperature or adopting a shorter wavelength laser. The study＇s results will provide the reference for the design of a water-direct-absorption-type high-energy laser energy meter as well as an analysis of the interaction processes of other similar high-power lasers and water flow.展开更多
Subsurface water flow above the weakly permeable soil layer commonly occurs on purple soil slopes.However,it remains difficult to quantify the effect of subsurface water flow on the surface flow velocity.Laboratory ex...Subsurface water flow above the weakly permeable soil layer commonly occurs on purple soil slopes.However,it remains difficult to quantify the effect of subsurface water flow on the surface flow velocity.Laboratory experiments were performed to measure the rill flow velocity on purple soil slopes containing a subsurface water flow layer with the electrolyte tracer method considering 3 subsurface water flow depths(SWFDs:5,10,and 15 cm),3 flow rates(FRs:2,4,and 8 L min^(-1)),and 4 slope gradients(SGs:5°,10°,15°,and 20°).As a result,the pulse boundary model fit the electrolyte transport processes very well under the different SWFDs.The measured rill flow velocities were 0.202 to 0.610 m s^(-1) under the various SWFDs.Stepwise regression results indicated a positive dependence of the flow velocity on the FR and SG but a negative dependence on the SWFD.The SWFD had notable effects on the rill flow velocity.Decreasing the SWFD from 15 to 5 cm increased the flow velocity.Moreover,the flow velocities under the 10-and 15-cm SWFDs were 89%and 86%,respectively,of that under the 5-cm SWFD.The flow velocity under the 5-,10-and 15-cm SWFDs was decreased to 89%,80%,and 77%,respectively,of that on saturated soil slopes.The results will enhance the understanding of rill flow hydrological processes under SWFD impact.展开更多
In order to improve and enhance the numerical modeling methods and its application on debris flow problems,a preliminary study has been proposed in accordance with the corrected water-sediment numerical model on the p...In order to improve and enhance the numerical modeling methods and its application on debris flow problems,a preliminary study has been proposed in accordance with the corrected water-sediment numerical model on the premise of revised resistance and sediment capacity equations.Firstly,an overview the recent re- search achievements on numerical simulation of debris flow has been conducted,the results shown that a gener- al numerical model for debris flow can not be existed at all because the complex rheol...展开更多
To improve the utilization rate of plasma active species,in this study,a closed non-uniform air gap is formed by a flowing water film electrode and a sawtooth insulating dielectric layer to realize the diffuse glow di...To improve the utilization rate of plasma active species,in this study,a closed non-uniform air gap is formed by a flowing water film electrode and a sawtooth insulating dielectric layer to realize the diffuse glow discharge in the atmosphere.Firstly,the electric field distribution characteristics of non-uniform air gap in the sawtooth dielectric layer are studied,and the influence of aspect ratio on the characteristics of diffuse discharge plasma is discussed.Subsequently,the effects of wire mesh,the inclination angle of the dielectric plate,and liquid inlet velocity on the flow characteristics of the water film electrode are analyzed.The results show that the non-uniform electric field distribution formed in the sawtooth groove can effectively inhibit the filamentous discharge,and the 1 mm flowing water film is directly used as the electrode,and high-active plasma is formed directly on the lower surface of the water film.In addition,a plasma flowing water treatment device is built to treat the methyl orange solution and observe its decolorization effect.The experimental results show that after 50 min of treatment,the decolorization rate of the methyl orange solution reaches 96%,which provides a new idea for industrial applications of wastewater treatment.展开更多
A two-dimensional mathematical model is used to simulate the influence of water flow on the piers of a bridge for different incidence angles.In particular,a finite volume method is used to discretize the Navier-Stokes...A two-dimensional mathematical model is used to simulate the influence of water flow on the piers of a bridge for different incidence angles.In particular,a finite volume method is used to discretize the Navier-Stokes control equations and calculate the circumferential pressure coefficient distribution on the bridge piers’surface.The results show that the deflection of the flow is non-monotonic.It first increases and then decreases with an increase in the skew angle.展开更多
基金National Natural Science Foundation of China,Grant/Award Number:41902292。
文摘Groundwater inrush is a hazard that always occurs during underground mining.Grouting is one of the most effective processes to seal underground water inflow for hazard prevention.In this study,grouting experiments are conducted by using a visualized transparent single-fracture replica with plane roughness.Image processing and analysis are performed to investigate the thermo–hydro–mechanical coupling effect on the grouting diffusion under coal mine flowing water conditions.The results show that higher ambient temperature leads to shorter initial gel time of chemical grout and leads to a better relative sealing efficiency in the case of a lower flow rate.However,with a higher water flow rate,the relative sealing efficiency is gradually reduced under higher temperature conditions.The grouting pressure,the seepage pressure,and the temperature are measured.The results reveal that the seepage pressure shows a positive correlation with the grouting pressure,while the temperature change shows a negative correlation with the seepage pressure and the grouting pressure.The“equivalent grouting point offset”effect of grouting shows an eccentric elliptical diffusion with larger grouting distance and width under lower temperature conditions.
基金supported by the National Natural Science Foundation of China(Grant No.42201302)the“Double First-Class”University Construction Project of Lanzhou University(Grant No.561120213)the Graduate Research Funding Project of Northwest Normal University(Grant No.2022KYZZ-S195).
文摘By introducing virtual water(VW)flow correlation coefficients and risk indicators,this study examines the VW transmission relationship between urban agglomerations and cities in the Yellow River Basin(YRB)and its impact on regional water resources pressure.The results show that:except for the Shandong Peninsula Urban Agglomeration(SPUA)and Central Plains Urban Agglomeration(CPUA),the other urban agglomerations primarily act as VW exporting regions,while virtual water-importing cities are concentrated in the eastern regions.Notably,the Ningxia Urban Agglomeration(NUA)demonstrates significantly higher VW impact and sensitivity coefficients values than the remaining six urban agglomerations.First-tier cities generally display lower virtual water impact and sensitivity coefficients,whereas emerging cities exhibit the opposite trend.Additionally,we observe uneven risk variations between VW importing and exporting regions.Taking NUA as an example,the risk increase resulting from VW exports significantly exceeds the risk reduction associated with VW imports in the corresponding regions.It’s important to highlight that first-tier cities consistently decrease water resource risk through VW imports in the study years.However,among second and third-tier cities,only 38.9%experience reduced water resource risk through VW imports.Therefore,we recommend a focused examination of VW imports and exports in western region urban agglomerations,cities,and second and third-tier cities within the watershed.Leveraging virtual water’s asymmetric and high-value transfer can alleviate water resource pressure and scarcity risks in high-pressure regions by shifting them to lower-pressure regions,thus mitigating water resource stress across regions.
基金the support from Natural Science Foundation of Heilongjiang Province(No.YQ2022A004)National Natural Science Foundation of China(No.12372268,No.12332014).
文摘As intelligent sensors for marine applications rapidly advance,there is a growing emphasis on developing efficient,low-cost,and sustainable power sources to enhance their performance.With the continuous development of triboelectric nanogenerators(TENGs),known for their simple structure and versatile operational modes,these devices exhibit promising technological potential and have garnered extensive attention from a broad spectrum of researchers.The single-electrode mode of TENGs presents an effective means to harness eco-friendly energy sourced from flowing water.In this study,the factors affecting the output performance were investigated using different structures of single-electrode solid-liquid TENGs placed in a circulating water tank.In addition,the solid‒liquid contact process was numerically simulated using the COMSOL Multiphysics software,and significant potential energy changes were obtained for the solid‒liquid contact and liquid flow processes.Finally,the energy generated is collected and converted to power several light-emitting diodes,demonstrating that solid‒liquid TENGs can generate effective electrical power in a flowing water environment.Through several experimental investigations,we finally determined that the flow rate of the liquid,the thickness of the friction electrode material,and the contact area have the most significant effect on the output efficiency of TENGs in the form of flowing water,which provides a guide for improving their performance in the future.
基金supported by the National Natural Science Foundation of China(No.12172029)the open Resarch Project of Key Laboratory of Icing and Anti/De-icing of CARDC(No.IADL 20230101)。
文摘The icing of areo-engine inlet components during flight can affect engine operational safety.Conventional hot-air anti-icing systems require a large amount of bleed air,which compromises engine performance.Consequently,low-energy anti/de-icing methods based on superhydrophobic surfaces have attracted widespread attention.Previous studies have demonstrated that for stationary components,superhydrophobic surfaces can significantly reduce anti-icing energy consumption by altering the flow behavior of runback water.However,for rotating inlet components of aero-engines,the effectiveness of superhydrophobic surfaces and the influence of surface wettability on the evolution of runback water flow remain unclear due to the effects of centrifugal and Coriolis forces.This study establishes a 3D liquid water flow simulation model using the volume of fluid(VOF)method to investigate the effects of rotational speed,airflow velocity,and surface wettability on the runback water flow behavior over the rotating spinner under dynamic rotation conditions.The results show that the rotational effects and surface wettability mutually reinforce one another.Specifically,increasing the rotational speed and contact angle can both enhance the flow velocity of liquid water and accelerate the breakup and rupture of liquid film,leading to the formation of rivulets,droplets,and subsequent detachment from the surface.A theoretical model based on force balance is proposed to describe the evolution of runback water flow,and the analysis reveals that as the rotational speed and contact angle increase,the water film is more likely to break up to form rivulets and beads,and the critical radius for droplet detachment from the surface decreases,making it easier removal from the surface.
基金supported by the Major Project of Hunan Natural Science Foundation,China(No.2021JC0010)the National Natural Science Foundation of China(No.51274251)。
文摘The existing deep-sea sediment plume tests are mostly under small-scale static water and rarely under large-scale flowing water conditions.In this study,large-scale tank experiments of flowing water were designed and conducted to investigate the morphological characteristics and concentration evolution of the sediment plumes under different discharge rates(Q)and initial sediment concentrations(c).Viscosity tests,resuspension tests and free settling tests of the sediment solution with different c values were performed to reveal the settling mechanism of the plume diffusion process.The results show that the plume diffusion morphology variation in flowing water has four stages and the plume concentration evolution has three stages.The larger the Q,the smaller the initial incidence angle at the discharge outlet,the larger the diffusion range,the poorer the stability and the more complicated the diffusion morphology.The larger the c,the larger the settling velocity,the faster the formation of high-concentration accumulation zone,the better the stability and the clearer the diffusion boundary.The research results could provide experimental data for assessing the impact of deep-sea mining on the ocean environment.
基金National Natural Science Foundation of China,No.42171258,No.U22A20611Joint Fund of Hunan Provincial Natural Science Foundation of China,No.2024JJ8350。
文摘The equilibrium between the supply and demand of water purification services is essential for safeguarding watershed ecosystems and supporting sustainable socio-economic growth.While current research mainly emphasizes the static analysis of this balance,dynamic investigations into service flow characteristics remain scarce.This study focuses on the Xiangjiang River Basin in southern China,utilizing the InVEST model,differential equations governing supply and demand,and social network analysis to investigate the spatio-temporal patterns of water purification service supply and demand.The results reveal that between 2000 and 2020,the supply of water purification services showed a slight upward trend,while demand exhibited a fluctuating downward tendency,and the supply-demand surplus fluctuated.On an annual basis,the supply generally met the demand,but significant spatial variation in supply-demand balance was observed,with high-risk zones concentrated in the central Hengshao arid corridor and the northern Changzhutan metropolitan area.In the water purification service network,surplus nodes increased,while deficit nodes decreased over time.Network density improved from 98.96%in 2000 to 100%in 2020.The flow of surplus services from upstream regions alleviated supply-demand imbalances downstream,notably in the Hengyang-Shaoyang(Hengshao)arid corridor and the Changsha-Zhuzhou-Xiangtan(Changzhutan)metropolitan area.However,during drought years,diminished water volume intensified supply-demand pressures in these regions.This research framework,which incorporates the dynamic effects of service flow,broadens the scope of water purification service studies and provides a solid foundation for integrated water resource and environmental management.
文摘Three tracing tests from the same injection point executed at low, medium, and high water levels in the karst aquifer near Tianshengan village, Lunan Stone Forest, Yunnan Province, China, have revealed the basic properties of underground water flow. They showed the general directions of water flows; tracer concentrations were observed at six successive points allowing for the calculation of apparent dominant flow velocities at these sections towards the Dalongtan karst spring. For the high water level, the discharge between single sections was between two and 10 times greater than that at low water level. For the medium water level, the flow velocity at different sections was between 1.4 and 3.7 times faster than that at low water level; and for high water level, it was between 1.3 and 2.7 times faster than that at medium water level. The fastest water flow appeared at the first section （23 cm/s at medium water level）; and the slowest （0.6 cm/s at low water level） appeared where water flow must cross the Tianshengan fault （north-south direction）, and later, a layer of 20-30 m thickness of quartz sandstone and shale clay-stones. It was also possible to calculate the recovery of the tracer for point 4, Dakenyan, where discharge was measured. At the medium water level, 50% of the injected tracer was detected a half-day after its first appearance and at low water level after more than 3 days. The previously published research illustrates the transport velocities of possible contaminants and their solubilities in water at different hydrological conditions.
基金supported by National Natural Science Foundation of China(grant number 42171258,41877084)Natural Science Foundation of Hunan Province(grant number 2021JJ30448)。
文摘Global climate change and increased human consumption have aggravated the uneven spatiotemporal distribution of watershed water resources, affecting the water provision supply and demand state. However, this problem has often been ignored. The present study used the Xiangjiang River basin(XRB) as the study area, and the Integrated Valuation of Ecosystem Services and Trade-offs(InVEST) model, demand quantification model,supply–demand ratio, and water flow formula were applied to explore the spatial heterogeneity, flow, and equilibrium between water supply and demand. The results demonstrated significant spatial heterogeneity in the upstream, midstream, and downstream regions.The areas of water shortage were mainly located the downstream of the Changsha–Zhuzhou–Xiangtan urban agglomeration, and the Hengyang basin was the most scarcity area. Affected by terrain gradients and human needs, water flow varied from-16.33 × 10^(8) m^(3) to 13.69 × 10^(8) m^(3)from the upstream to the downstream area, which provided a possibility to reduce spatial heterogeneity. In the future, measures such as strengthening water resource system control,sponge city construction, and dynamic monitoring technology should be taken to balance the supply and demand of water in different river sections of the basin. This study can provide references for regulating water resources allocation in different reaches of the basin.
基金supported by the National Natural Science Foundation of China (Grant No.10872144)the Support Plan of Science and Technology of Tianjin (Grant No.07ZCGYSH01700)
文摘To deal with the moving boundary hydrodynamic problems of the tidal flats in shallow water flow models, a new wetting and drying （WD） method is proposed. In the new method, a ＂predicted water depth＂ is evaluated explicitly based on the simplified shallow water equations and used to determine the status （wet or dry） together with the direction of flow. Compared with previous WD method, besides the water elevation, more factors, such as the flow velocity and the surface shear stress, are taken into account in the new method to determine the moving boundary. In addition, a formula is deduced to determine the threshold, as critical water depth, which needs to be preset before simulations. The new WD method is tested with five cases including three 1D ones and two 2D ones. The results show that the new WD method can simulate the wetting and drying process, in beth typical and practical cases, with smooth manner and achieves effective estimation of the retention volume at shallow water body.
基金Project(50490274) supported by the National Natural Science Foundation of ChinaProject(200516) supported by Hunan Transportation Science and Technology
文摘Based on a typical multi-arch tunnel in a freeway, the fast Lagrangian analysis of continua in 3 dimensions(FLAC3D) was used to calculate the surrounding rock deformation of the tunnel under which the effect of underground water seepage flow was taken into account or not. The distribution of displacement field around the multi-arch tunnel, which is influenced by the seepage field, was gained. The result indicates that the settlement values of the vault derived from coupling analysis are bigger when considering the seepage flow effect than that not considering. Through the contrast of arch subsidence quantities calculated by two kinds of computation situations, and the comparison between the calculated and measured value of tunnel vault settlement, it is found that the calculated value(5.7-6.0 mm) derived from considering the seepage effect is more close to the measured value(5.8-6.8 mm). Therefore, it is quite necessary to consider the seepage flow effect of the underground water in aquiferous stratum for multi-arch tunnel design.
基金The National Natural Science Foundation of China under contract No.51609168the Science and Technology Program of CNOOC Limited under contract No.YXKY-2016-2Y-07+2 种基金the Open Fund of State Key Laboratory of Coastal and Offshore Engineering under contract No.LP1608the National Basic Research Program(973 Program)of China under contract No.2014CB046804the National Science and Technology Major Project under contract No.2016ZX05057020
文摘A physical model test has been conducted to study the oil diffusion from the submarine pipeline under water flow.The crude oil in the flume is spilled from a leakage point of the pipeline and diffused from the seabed to the surface. By the non-contact optical measuring technology, an image acquisition and data analysis system is designed to explore the spilled mechanism and characteristic. The oil trajectory, velocity and the rising time to the surface are obtained through this system. The influence of the water flow and the spilled discharge on the behavior of the spilled oil are analyzed from both qualitative and quantitative perspectives. The sensitivity study of the characteristic physical quantities to various factors are presented afterward. The spilled oil under water is mainly distributed in the form of the scattered particles with different sizes. The rising process of the oil can be divided into three stages: full, dispersion and aggregation period. The spilled discharge is the primary factor affecting the rising time of the oil particles. In the rising process of the oil particles, the vertical velocity of the oil is mainly affected by the spilled discharge, and the transverse velocity is more dependent on the water velocity. The deviation of the transverse oil velocity is much larger than that of the rising time and the vertical oil velocity. The study can provide a theoretical reference for the prediction system of oil spill emergency.
基金Transport Canada for financial support and Yukon Highways and Public Works for their support,logistics and assistance during instrumentation at the new Beaver Creek Culvert and information regarding the rules for construction of culverts in Yukon
文摘Temperature and water flow through a culvert beneath the Alaska Highway near Beaver Creek,Yukon,were measured at hourly intervals between June and October 2013.These data were used to simulate the effect of the culvert on the thermal regime of the road embankment and subjacent permafrost.A 2-D thermal model of the embankment and permafrost was developed with TEMP/W and calibrated using field observations.Empirical relations were obtained between water temperatures at the entrance to the culvert,flow into the culvert,and water temperatures inside the structure.Water temperatures at the entrance and inside the culvert had a linear relation,while water temperatures inside the culvert and water flow were associated by a logarithmic relation.A multiple linear regression was used to summarize these relations.From this relationship,changes in the flow rate and water temperatures at the entrance of the culvert were simulated to obtain predicted water temperatures in the culvert.The temperatures in the culvert were used in the thermal model to determine their effects on the ground thermal regime near the culvert.Variation of ±10% in water flow rate had no impact on the thermal regime underneath the culvert.Variation of water temperature at the entrance of the culvert had a noticeable influence on the thermal regime.A final simulation was conducted without insulation beneath the culvert.The thaw depth was 30 cm with insulation,and 120 cm without insulation,illustrating the importance of insulation to the ground thermal regime.
基金Supported by the National Natural Science Foundation of China(50974095,41174109,61104148)the National Science and Technology Major Projects(2011ZX05020-006)
文摘This paper presents the characteristics of a double helix capacitance sensor for measurement of the liquid holdup in horizontal oil–water two-phase flow. The finite element method is used to calculate the sensitivity field of the sensor in a pipe with 20 mm inner diameter and the effect of sensor geometry on the distribution of sensitivity field is presented. Then, a horizontal oil–water two-phase flow experiment is carried out to measure the response of the double helix capacitance sensor, in which a novel method is proposed to calibrate the liquid holdup based on three pairs of parallel-wire capacitance probes. The performance of the sensor is analyzed in terms of the flow structures detected by mini-conductance array probes.
基金the National Natural Science Foundation of China (Grant No.10702050)the Natural Science Foundation of Tianjin (Grant No.07JCYBJC07500)the Support Plan of Science and Technology of Tianjin (Grant No.07ZCGYSH01700)
文摘A particular porosity method named ＂slot method＂ is implemented in a depth-integrated shallow water flow model （DIVAST） to simulate wetting and drying processes. Discussed is the relationship between the shape factors of the ＂slot＂ and the preset depth used in ＂wetting-drying＂ algorithm. Two typical tests are conducted to examine the performance of the method with the effect of the shape factors of the ＂slot＂ being checked in detail in the first test. Numerical results demonstrate that： 1 ） no additional effort to improve the finite difference scheme is needed to implement ＂slot method＂ in DIVAST, and 2） ＂slot method＂ will simulate wetting and diying processes correctly if the shape factors of the ＂slot＂ being selected properly.
基金Financial support for this work,provided by the National Natural Science Foundation of China(Nos.40772192 and 41072237)the State Key Laboratort of Geomechanics and Deep Underground Engineering(No.SKLGDUEK0903)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20100095110015)
文摘We present a series of experimental tests on chemical grouting into a fracture with flowing and static water,using a transparent fracture grouting experimental device.Variations of seepage pressure and grout propagation were compared in our investigation.The results show that flowing water results in drops of seepage pressure,development of penetration radii in the upstream side and drops of propagation area during the same period,compared with grouting in static water.The propagation area in static water is always round before grouts reach the joint boundaries.However,the propagation shape changes from round to an elliptic shape for grouting into a fracture with flowing water.A theoretical model for the grout penetration radius in a fracture considering flowing velocity was developed and validated by our experimental results.These results are helpful in improving understanding of fracture grouting mechanism and in guiding engineering practices.
文摘In the absorption chamber of a high-energy laser energy meter, water is directly used as an absorbing medium and the interaction of the high-power laser and the water flow can produce a variety of physical phenomena such as phase transitions. The unit difference method is adopted to deduce the phase transition model for water flow irradiated by a high-energy laser. In addition, the model is simulated and verified through experiments. Among them, the experimental verification uses the photographic method, shooting the distribution and the form of the air mass of water flow in different operating conditions, which are compared with the simulation results. The research shows that it is achievable to reduce the intensity of the phase transition by increasing the water flow, reducing the power intensity of the beam, shortening the distance the beam covers, reducing the initial water temperature or adopting a shorter wavelength laser. The study＇s results will provide the reference for the design of a water-direct-absorption-type high-energy laser energy meter as well as an analysis of the interaction processes of other similar high-power lasers and water flow.
基金financially supported by the National Natural Science Foundation of China(Nos.41571265 and 42177314)the Key Research and Development Project of Social Livelihood in Chongqing(cstc2018jscx-mszd X0061)the Foundation of Graduate Research and Innovation in Chongqing(CYS21114)。
文摘Subsurface water flow above the weakly permeable soil layer commonly occurs on purple soil slopes.However,it remains difficult to quantify the effect of subsurface water flow on the surface flow velocity.Laboratory experiments were performed to measure the rill flow velocity on purple soil slopes containing a subsurface water flow layer with the electrolyte tracer method considering 3 subsurface water flow depths(SWFDs:5,10,and 15 cm),3 flow rates(FRs:2,4,and 8 L min^(-1)),and 4 slope gradients(SGs:5°,10°,15°,and 20°).As a result,the pulse boundary model fit the electrolyte transport processes very well under the different SWFDs.The measured rill flow velocities were 0.202 to 0.610 m s^(-1) under the various SWFDs.Stepwise regression results indicated a positive dependence of the flow velocity on the FR and SG but a negative dependence on the SWFD.The SWFD had notable effects on the rill flow velocity.Decreasing the SWFD from 15 to 5 cm increased the flow velocity.Moreover,the flow velocities under the 10-and 15-cm SWFDs were 89%and 86%,respectively,of that under the 5-cm SWFD.The flow velocity under the 5-,10-and 15-cm SWFDs was decreased to 89%,80%,and 77%,respectively,of that on saturated soil slopes.The results will enhance the understanding of rill flow hydrological processes under SWFD impact.
基金Supported by National Scientific Foundation of China(Study on of Basis Theory and Prediction of Debris Flow,40025103)
文摘In order to improve and enhance the numerical modeling methods and its application on debris flow problems,a preliminary study has been proposed in accordance with the corrected water-sediment numerical model on the premise of revised resistance and sediment capacity equations.Firstly,an overview the recent re- search achievements on numerical simulation of debris flow has been conducted,the results shown that a gener- al numerical model for debris flow can not be existed at all because the complex rheol...
基金financially supported by National Natural Science Foundation of China(No.51577011)。
文摘To improve the utilization rate of plasma active species,in this study,a closed non-uniform air gap is formed by a flowing water film electrode and a sawtooth insulating dielectric layer to realize the diffuse glow discharge in the atmosphere.Firstly,the electric field distribution characteristics of non-uniform air gap in the sawtooth dielectric layer are studied,and the influence of aspect ratio on the characteristics of diffuse discharge plasma is discussed.Subsequently,the effects of wire mesh,the inclination angle of the dielectric plate,and liquid inlet velocity on the flow characteristics of the water film electrode are analyzed.The results show that the non-uniform electric field distribution formed in the sawtooth groove can effectively inhibit the filamentous discharge,and the 1 mm flowing water film is directly used as the electrode,and high-active plasma is formed directly on the lower surface of the water film.In addition,a plasma flowing water treatment device is built to treat the methyl orange solution and observe its decolorization effect.The experimental results show that after 50 min of treatment,the decolorization rate of the methyl orange solution reaches 96%,which provides a new idea for industrial applications of wastewater treatment.
文摘A two-dimensional mathematical model is used to simulate the influence of water flow on the piers of a bridge for different incidence angles.In particular,a finite volume method is used to discretize the Navier-Stokes control equations and calculate the circumferential pressure coefficient distribution on the bridge piers’surface.The results show that the deflection of the flow is non-monotonic.It first increases and then decreases with an increase in the skew angle.
