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Low friction ice sliding interfaces were critical for ski performance optimization. Traditional fluorinated ski waxes have attracted considerable attention for enhancing the hydrophobicity, anti-wearing, and oxidation resistance of ski-ice base. However, the toxicity and complexity of the waxing process limited batch manufacturing of low-cost and non-toxic ski-ice base, what is more, the wax covering on the base wore and failed during skiing due to the friction between ski and ice. Herein, we demonstrated a novel ultra-high molecular weight polyethylene (UHMWPE) composite that could maintain a low coefficient of friction (COF) with about 0.026 for at least 160 min when skiing on the ice. Microcapsule (MS) could release liquid (liquid paraffin (LP)). The released LP further enhanced the hydrophobicity of UHMWPE's surfaces when friction occurred, which would maintain the stability and durability of the water film, and achieved superior and long-lasting friction resistance. Compared with other microcapsules with lower hydrophobic core, microcapsules with LP performed the best in reducing the friction of ski base from 0.126 to 0.024. Meanwhile, the COF of the surface kept at about 0.02 even after 12 rapid temperature changes. The presented UHMWPE composite of encapsulated liquids showed great potential and broad application owing to its simplicity and efficiency in winter sports. [ABSTRACT FROM AUTHOR]

The study of nano-scratching under water lubrication is helpful to understand the role of lubrication mechanism in the machining of single crystal γ-TiAl alloy. In this paper, through the comparative analysis of nano-scratching under different thicknesses of water layers, it was found that under a water layer thickness of 1 nm, nano-scratching not only improves the surface quality but also achieves multiple reductions in scratch force, stress, temperature and subsurface structural damage. In order to deeply reveal the internal mechanism of workpiece temperature variation under different thicknesses of water layer lubrication, a fitting formula was innovatively adopted to conduct quantitative analysis. In addition, with the increase of the thickness of the water layer, it was observed that the water film effect was continuously enhanced, and this change caused the matrix stress to gradually increase, which hindered the forward motion of the nanoscratch, ultimately resulting in an increase in the friction coefficient. These findings provide valuable insights into the nanoscratching mechanism of monocrystalline γ-TiAl alloy in the presence of water film, and provide a new perspective for understanding the complex mechanism of nanoscratch behaviour under water lubrication, thus promoting the understanding of nanoscale lubrication effects. [ABSTRACT FROM AUTHOR]

The coal chemical industry, as the main source of carbon emissions in China, will face great challenges under the constraints of the dual carbon goals. Coal derived gas deep desulfurization is an important component for highly efficient and clean utilization of coal, which is of great significance for carbon reduction. Zinc oxide is a commonly used adsorbent for desulfurization, but due to kinetic limitations, its room temperature desulfurization reactivity is very low, and this cannot meet the requirements of industrial application. Pore diffusion is a prerequisite for the reaction between ZnO and H2S, and is crucial for desulfurization performance. However, the influence of pore size, especially macropores, on the desulfurization performance and its mechanism have been rarely reported. For this reason, two ZnO/SiO2 adsorbents with mesopores and macropores in this study were prepared using a sol-gel method and a colloidal crystal template method, respectively, and the influence of macropores on their room temperature desulfurization performance was explored. It is found that although the introduction of macropores increases the specific surface area of the adsorbent, strengthens its surface alkalinity, improves the dispersion of ZnO, and increases the concentration of oxygen vacancies in the adsorbent, its introduction leads to a remarkable decrease in the desulfurization performance of adsorbent. The breakthrough sulfur capacity of mesoporous adsorbent is 151.9 mg/g, 2.3 times than that of macroporous adsorbent. This is because the macroporous structure is unstable and prone to collapse during the desulfurization process, which hinders the accessibility of reaction sites of ZnO; Secondly, the water vapor in the atmosphere is not conducive to the formation of a water film on the surface of macropores, thereby inhibiting the occurrence of desulfurization reactions. More importantly, the combustion of the template releases a large amount of heat during the preparation of macropores, which leads to a deep crosslinking of the SiO2 network and a decrease in the mesoporous pore size of adsorbent. The smaller mesoporous pore size results in an excessive amount of water physically adsorbed on its surface, inhibiting the reaction between ZnO and H2S.

The simultaneous oblique impact of multiple droplets on a liquid film is an intricate phenomenon prevalent in diverse natural and industrial processes. However, previous studies have primarily focused on single droplet impact, while an in-depth understanding of the more complex multi-droplet scenario remains lacking. The current study aims to numerically investigate the simultaneous oblique impact of two droplets on a water film using a three-dimensional Volume of Fluid (VOF) model. The effects of the Weber number and the impact angle on the crown behavior are carefully analyzed. The results demonstrate that increasing the Weber number enhances the central uprising sheet height but has minor influences on the upstream crown radius and central sheet radius. In contrast, the increase in the impact angle leads to a decreased upstream crown radius and an increased central sheet radius, while the central sheet height remains relatively unaffected. In addition, the splashing threshold for the dual droplet impact cases is significantly lower than that of the single droplet impact cases due to the interactions between the adjacent crowns. The present results provide novel insights into the underlying physics and useful supports in developing predictive models for the intricate multi-droplet impact phenomenon. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ballistics / Dandao Xuebao is the property of Journal of Ballistics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to figure out the influence of water film on the performance of the turbomachinery, understand the mechanism of the interaction between the high-speed airflow and the water film in turbomachinery, and provide a reference for the design of the subsequent experiments and hollow stationary blade water removal by heating. The commercial software FLUENT with the Eulerian Wall Films model is used to establish a solution method for simulating the flow of water film on the blade. The accuracy of the solution method is verified by comparing it with the results of the water film thickness experiment on the surface of the plate. The distribution of the water film on the outer surface of the vane as well as the influence of the water film on the mainstream field are numerically studied in the condition of the wet steam mainstream. The results show that the gradient of water film thickness on the pressure surface is relatively gentle and is along the radial direction. The gradient of water film thickness on the suction side is along the axial direction, and the value is larger; There is a V-shaped water film agglomeration area on the suction surface near the trailing edge where the water film thickness is greater than 45.7 μm; The top areas on both the suction side and pressure side produce a local water film agglomeration area with the dual effect of the secondary flow and the centrifugal force of the mainstream; The water film flow on the blade surface has little influence of the steam velocity and the speed of the mainstream. The increase of local pressure on the surface leads to an increase in the pressure of the adjacent mainstream areas. [ABSTRACT FROM AUTHOR]

Through the design of the ceramic plunger pump for hemodialysis, the mathematical model of the water film of the plunger pair of the ceramic plunger pump was built. The distribution characteristics of the speed and pressure of the water film of the plunger pair were analyzed, and the temperature distribution characteristics of the water film surface were obtained. The effects of inlet pressure, inlet temperature, rotational speed, and chamber temperature on the water film temperature of the plunger pair were studied. Experiments and analysis show that the closer the temperature of the plunger pair is to the inlet of purified water, the smaller the temperature change. The farther the ceramic plunger rod is from the inlet of purified water, the greater the temperature change, and the main influencing points are concentrated inside the plunger pair. Therefore, maintaining a certain amount of purified water temperature, pressure, and flow rate for lubrication is crucial for the service life of ceramic piston pumps. [ABSTRACT FROM AUTHOR]

For an aero turbo-shaft engine, rain water enters the intake protection device and the morphology of water droplets after hitting the wall will affect the internal flow of the compressor. In this paper, Sommerfeld number was used to determine the shape of water droplets after they hit the wall. The flow field and characteristics of the compressor with inlet particle separator under different water ingestion conditions were studied with considering the impact of water film and droplets splashing near the wall. The results show that the entry of water droplets deteriorates the internal flow field of the compression component, and the water film affects the flow state of the airflow near the wall. Compared to the effect of the splashing factor, the viscous resistance effect of water film near the wall on the airflow and boundary layer can cause a significant reduction in the characteristics and stability of the compressor. [ABSTRACT FROM AUTHOR]

The frenzied demand for the transit of humans and commodities in this modern world requires aircraft to operate in adverse weather conditions of rainfall, ice accretion, and gust. The paper also introduces innate characteristics of rainfall, ultimatum due to precipitation. The work gives a brief overview of adverse effect of rainfall on aerodynamic characteristics for various phases of flight in terms of evaluation of the aircraft performance flight characteristics such as CL, CD, L/D. It also portrays the significant phenomenon of boundary layer transition at lower AOA near leading edge and flow separation taking place nearby trailing edge at higher AOA. The study also showcases presence of uneven water film on wing surface due to droplet impingement, instabilities, interaction of water droplets with air flowing over the airfoil and splitting into rivulets which results in degradation of aerodynamic characteristics. The findings of this review paper could be of immense use to aviation industries in developing an aircraft that has better aerodynamic characteristics for all weather conditions. [ABSTRACT FROM AUTHOR]

Earthquake-triggered mudflows are typical in scale and hazard, and their formation mechanism is extremely complex. In this study, the liquefaction and mobility mechanisms of a catastrophic mudflow, namely, the Yongguangcun (YGC) mudflow, in Minxian, Gansu Province, China, under the coupled action of historical earthquakes, active faults, groundwater, long-term rainfall before an earthquake, and the 2013 Mw6.6 Minxian–Zhangxian earthquake were systematically analyzed. Through a detailed field investigation and laboratory testing, the stratigraphic structure of the YGC mudflow was revealed, a geomechanical model was established, and the complex chain process leading to the formation of the YGC mudflow was elucidated. This process includes sliding along the contact zone between the loess and strongly weathered mudstone, liquefaction of the saturated loess under the groundwater table, and liquefaction and collapse of the unsaturated loess above the groundwater table. The slightly low terrain provides the topographic conditions required for groundwater convergence, and sets the conditions for the deformation and further liquefaction of saturated loess during earthquakes. The undulating terrain in the meizoseismal area enhances the complexity of the earthquake waves. In summary, the YGC mudflow was caused by long-term geological evolution and the synergistic effects of other factors; and the site conditions, such as the local topography and groundwater, are the fundamental reasons for the failure and mobility differences between the YGC mudflow and the eastern landslide. The results of the investigation of this mudflow would enrich our understanding of mudflows, promote research on the formation mechanism of geological disasters under complex conditions on the Loess Plateau, and provide important information for improving the scientific prevention and control of landslides of the same type. [ABSTRACT FROM AUTHOR]

Many rubber friction theories or some method combined theories and field-experiments are employed to evaluate the pavement skid-resistance deterioration due to the evolution of surface textures. However, these methods are difficult to be implemented in the analysis of situations with multi-factor coupling and some extreme conditions. This study developed a framework to evaluate the skid-resistance deterioration of asphalt pavements. In this framework, the portable laser scanning was used to create the digital worn pavement model, and a hydroplaning finite element (FE) model for these digital worn pavements was constructed to evaluate coupling effects of the texture evolution and factors of slip ratio, slip angle, velocity and water film on braking-cornering characteristics of tire. In this study, the deterioration of skid-resistance of five typical asphalt pavements due the surface texture wear was systematically investigated by this framework. Compared with previous works, this study established the rubber friction models for each digital worn pavement considering the energy hysteresis of rubber and the power spectrum density of surface texture. And the rubber friction model was used to define the interaction behaviors between the tire and corresponding wore pavements in the FE hydroplaning model, rather than using an empirical friction model or a fixed friction coefficient. [ABSTRACT FROM AUTHOR]

Since the solar irradiation is accessible in many parts of our planet, it is a viable replacement for fossil fuels, so commissioning photovoltaic (PV) power plants are increased, rapidly. One of the main problems that this technology faces is the increase in the temperature of solar cells. In this paper, streaming water layer over the upper side of PV modules is considered as a cooling method. This technique not only lowers the surface temperature, but also keeps the surface clean. Four different water flow rates of 0.5, 1, 2, and 4 lit/min were used so that two different flow patterns, water streaks and water film, were formed. In addition, the negative effect of the residual water layer over the surface of the PV panel on the absorbed radiation was evaluated experimentally. As results, temperature drops of 20.6 °C and 29.7 °C were measured for flow rates of 0.5 and 2 lit/min, respectively. Also, for the case of 4 lit/min, the efficiency is increased by 6.7% compared to the conventional case. Moreover, it was observed that after the formation of a water layer, the water flow rate no longer has a significant effect on cooling. Finally, a comparison between the electrical efficiency enhancements of this study with those of similar researches was performed. [ABSTRACT FROM AUTHOR]

In the macroscopic soil mechanic experiment, the occurrence of cracks and failures of clay soil is intimately related to the nanoscale shear behavior of clay mineral sheets, which urgently needs to be studied. The two basal surfaces of kaolinite have different wettabilities with water molecules, thereby playing a significant role in microshear processes. In this article, the molecular dynamics (MD) simulation method was used to study the shear properties of hydrated kaolinite as a function of the water content and wettability Three shear models with different wettability (i.e., the hydrophilicity and hydrophobicity) and water content were established. According to the stick–slip effect of the curves of friction, 1W (one layer of saturated water molecules between clay mineral sheets) is the microplastic limit water content of kaolinite that transitions from brittle failure to ductile failure. By analyzing the basal spacing and the shear viscosity in the hydrophilic/hydrophobic model, the mosaic layer and vacuum layer at the clay–water interface and the condensation behavior of water molecules were observed. The friction of hydrated kaolinite was weakened significantly by the interparticle water film, which decreases by 64.30%–98.38% compared to the dry case. In hydrated kaolinite, the hydrophilic model has the strongest interfacial friction force due to the strong interaction between clay–water. While in dry cases the interfacial friction of the hydrophobic model is not the weakest among the three models, as the interaction between clay–clay has a larger component in the friction direction. Additionally, the hydrophilic/hydrophobic basal surface of hydrated kaolinite exhibits unique shear properties by affecting the interfacial friction, the hydrogen bond effect, and the flow of interparticle water. The simulation study on the shear behavior of hydrated kaolinite explains the microscale failure mechanism of clay soil, which has significance for disaster prevention and reduction projects such as landslide treatment. [ABSTRACT FROM AUTHOR]

Wet electrostatic agglomeration (WEA) is a very promising method in fine particle removal, however, it is still a challenging problem to avoid short-circuiting of the equipment caused by spraying water during traditional WEA. In this work, a novel WEA process based on a water film was established for the first time, and the fine particle removal and process mechanism were investigated. The influence of discharge and ground electrodes on the particle agglomeration performance was studied, indicating that a much better agglomeration performance was obtained by the spike plate (discharge electrode) thanks to the stronger electric field covering the entire agglomeration area. The corrosion-resistant and low-priced polyvinyl chloride (PVC) plate could significantly improve the water distribution effect after surface grooving modification, and its agglomeration as a grounding electrode under wet conditions was comparable to that of the wet metal plate. The mechanism of the water film enhanced WEA process lay in the fact that the high-voltage electric field greatly promotes the evaporation of the water film, which increased the humidity in the agglomeration space, resulting in liquid bridge force between the water-absorbing particles. In summary, this work provides an alternative novel idea for enhancing the agglomeration performance of the traditional WEA process. [ABSTRACT FROM AUTHOR]

Rapid urbanization and industrialization have heightened concerns about air quality worldwide. Conventional air purification methods, reliant on chemicals or energy-intensive processes, fall short in open spaces and in combating emerging pollutants. Addressing these limitations, this study presents a novel water-film air purification prototype leveraging the adhesion between low-curvature liquid surfaces and air convection friction. Uniquely designed, this prototype effectively targets toxic gases (e.g., formaldehyde, SO2, NO2) and particulate matter (such as PM2.5) while allowing continuous airflow. This research explores the adhesion and sedimentation capabilities of a low-curvature water solution surface under convection friction, reducing the surface energy to remove airborne pollutants efficiently. The prototype was able to reduce the initial concentration in a 30 m³ chamber within 180 min by 91% for formaldehyde, 78% for nitrogen dioxide (NO2), 99% for sulfur dioxide (SO2), and 96% for PM2.5. Experimentally validated indicators—decay constants, CADR, and purification efficiency—enable a comprehensive evaluation of the purification device, demonstrating its efficacy in mitigating air pollution. This innovative design, which is cost-effective due to its use of easily accessible components and water as the primary medium, indicates strong potential for large-scale deployment. This study points to an environmentally friendly and economical approach to air purification, shedding light on a promising direction for enhancing indoor air quality. Further optimization and exploration of diverse pollutants and environmental conditions will propel the practical applications of this pioneering technology. [ABSTRACT FROM AUTHOR]

Abstract Many rubber friction theories or some method combined theories and field-experiments are employed to evaluate the pavement skid-resistance deterioration due to the evolution of surface textures. However, these methods are difficult to be implemented in the analysis of situations with multi-factor coupling and some extreme conditions. This study developed a framework to evaluate the skid-resistance deterioration of asphalt pavements. In this framework, the portable laser scanning was used to create the digital worn pavement model, and a hydroplaning finite element (FE) model for these digital worn pavements was constructed to evaluate coupling effects of the texture evolution and factors of slip ratio, slip angle, velocity and water film on braking-cornering characteristics of tire. In this study, the deterioration of skid-resistance of five typical asphalt pavements due the surface texture wear was systematically investigated by this framework. Compared with previous works, this study established the rubber friction models for each digital worn pavement considering the energy hysteresis of rubber and the power spectrum density of surface texture. And the rubber friction model was used to define the interaction behaviors between the tire and corresponding wore pavements in the FE hydroplaning model, rather than using an empirical friction model or a fixed friction coefficient.

Bubble, pore throat and water film will significantly affect the seepage characteristics of pore water. Based on the theory of porous media and mass and momentum conservation of pore water, this research investigates the blocking effects of bubble, pore throat and water film on the seepage water. According to the bubble force balance relationship, there exists a threshold ΔP at the pore throat. It is discovered through theoretical analysis that the small bubble cannot obstruct the pore throat, while the large bubble could pass through the pore throat after deforming and rupturing as the water pressure is greater than ΔP. In contrast, the bubble cannot pass through the pore throat and will block the water seepage. Meanwhile, the energy will be consumed in the aforementioned process, which will cause a drop in the pressure and seepage velocity of pore water along the seepage path, resulting in the non-uniform seepage characteristics of pore water. Combined with theoretical analysis, considering the factors of water injection pressure and pore size, the seepage and distribution characteristics of pore water are evaluated from macro- and micro-levels through sandstone water injection tests and numerical simulation analysis. Two experimental findings are very consistent, both reflect the non-uniform seepage characteristics of pore water and validate the rationality and precision of the theoretical analysis about the throat threshold ΔP. The findings of this study have certain theoretical reference significance for the theoretical research and practical engineering application about pore water seepage. [ABSTRACT FROM AUTHOR]

To manage energy-efficient indoor air quality, mechanical ventilation with a heat recovery system provides an effective measure to remove extra moisture and air contaminants, especially in bathrooms. Previous studies reveal that heat recovery technology can reduce energy consumption, and its calculation needs detailed information on the thermal performance of exhaust air. However, there are few studies on the thermal performance of bathroom exhaust air during and after showers. This study proposed a detailed thermal performance prediction model for bathroom exhaust air based on the coupled heat and mass transfer theory. The proposed model was implemented into the AccuRate Home engine to estimate the thermal performance of residential buildings with heat recovery systems. The time variation of the water film temperature and thickness on the bathroom floor can be estimated by the proposed model, which is helpful in determining whether the water has completely evaporated. Simulation results show that changing the airflow rate in the bathroom has little effect on drying the wet floor without additional heating. The additional air heater installed in the bathroom can improve floor water evaporation efficiency by 24.7% under an airflow rate of 507.6 m3/h. It also demonstrates that heat recovery can significantly decrease the building energy demand with the fresh air load increasing and contribute about 0.6 stars improvement for the houses in Hobart (heating-dominated region). It may be reduced by around 3.3 MJ/(m2·year) for the houses in other regions. With this study, guidelines for optimizing the control strategy of the dehumidification process are put forward. [ABSTRACT FROM AUTHOR]

To elucidate the effect of water film on the behavior of single-crystal cubic silicon carbide (SiC) under nano-indentation, molecular dynamics (MD) simulations were employed in this work. Results showed that a pop-in event occurs during nano-indentation, which is jointly controlled by the atomic amorphization and dislocation nucleation. Compared to substrate without any water film, the depth of the incipient pop-in event of the substrate decreases with the thickness of water film, where the larger the water film thickness, the lower the depth. Therefore, it is concluded that the plasticity of the material is improved with the addition of water film. Besides, the number and length of dislocations of the substrate increase with the water film, and the migration of perfect dislocations in the [110] crystal direction of packed {111} plane also become homogenized. As the water film thickness increases, dislocation activities become more prevalent; however, the recovery of deformed crystal structure gets restrained. Owing to the increase of hydrostatic stress, the sub-surface damage of the substrate is exacerbated with the water film. In addition, the surface bulge of the substrate ascends with the water film. Finally, it is observed that the inhomogeneity of the surface bulge distribution is boosted with increasing water film thickness, while the adhesion of amorphous atoms to the diamond indenter is weakened. [ABSTRACT FROM AUTHOR]

Accurate knowledge of gas flow within the reservoir and related controlling factors will be important for enhancing the production of coal bed methane. At present, most studies focused on the permeability evolution of dry coal under gas adsorption equilibrium, gas flow and gas diffusion within wet coal under the generally non-equilibrium state are often ignored in the process of gas recovery. In this study, an improved apparent permeability model is proposed which accommodates the water and gas adsorption, stress dependence, water film thickness and gas flow regimes. In the process of modeling, the water adsorption is only affected by water content while the gas adsorption is time and water content dependent; based on poroelastic mechanics, the effective fracture aperture and effective pore radius are derived; and then the variation in water film thickness for different pore types under the effect of water content, stress and adsorption swelling are modeled; the flow regimes are considered based on Beskok’s model. Further, after validation with experimental data, the proposed model was applied to numerical simulations to investigate the evolution of permeability-related factors under the effect of different water contents. The gas flow in wet coal under the non-equilibrium state is explicitly revealed.

The simultaneous oblique impact of multiple droplets on a liquid film is an intricate phenomenon prevalent in diverse natural and industrial processes. However, previous studies have primarily focused on single droplet impact, while an in-depth understanding of the more complex multi-droplet scenario remains lacking. The current study aims to numerically investigate the simultaneous oblique impact of two droplets on a water film using a three-dimensional Volume of Fluid (VOF) model. The effects of the Weber number and the impact angle on the crown behavior are carefully analyzed. The results demonstrate that increasing the Weber number enhances the central uprising sheet height but has minor influences on the upstream crown radius and central sheet radius. In contrast, the increase in the impact angle leads to a decreased upstream crown radius and an increased central sheet radius, while the central sheet height remains relatively unaffected. In addition, the splashing threshold for the dual droplet impact cases is significantly lower than that of the single droplet impact cases due to the interactions between the adjacent crowns. The present results provide novel insights into the underlying physics and useful supports in developing predictive models for the intricate multi-droplet impact phenomenon.

Copyright of Chinese Journal of Refrigeration Technology is the property of Shanghai Society of Refrigeration and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The CFD numerical study of the flash boiling phenomenon of a water film was conducted using an Euler–Euler method, and compared to the experiments on the flashing of a water film. The water film is initially heated at temperatures ranging from 34 to 74 ∘ C (frim 1 to 41 ∘ C superheat), and the pressure is decreased from 1 bar to 50 mbar during the experiments. This paper shows that the experiments could not be correctly modelled by a simple liquid/bubble model because of the overestimation of the drag force above the water film (in the gas/droplet region). The generalised large interface model (GLIM), however, a multi-regime approach implemented in the version 7.0 of the neptune_cfd software, is able to differentiate the water film, where liquid/bubble interactions are predominant from the gas region where gas/droplet interactions are predominant, and gives nice qualitative results. Finally, this paper shows that the interfacial heat transfer model of Berne for superheated liquids could accurately predict the evolution of the water temperature over time. [ABSTRACT FROM AUTHOR]

Gas flow properties in nanopores are significantly determined by the flow patterns. Slug flow pattern is a potential wateregas two phase flow pattern, in which gas molecules flow in form of gas slugs and water molecules separate gas slugs. Considering water slippage, a portion of water molecules accumulates at the wall with lower mobility, while the remaining water molecules take the shape of a water bridge. Adopting foam apparent viscosity model to represent slug rheological behavior, how water bridge disturbs on gas flow capacity is estimated. The results are compared with the wateregas two phase flow model that assumes annular flow pattern as well as the single gas flow model without the consideration of water. The comparison illustrates that gas molecular movement is significantly hindered by flow space reduction and loss of gas slippage. The impact from water phase of slug flow pattern is more significant than that of annular flow pattern on gas flow capacity. It is discovered that larger nanopores improve gas flow capacity while maintaining bulk water layer thickness and increasing water bridge thickness tend to reduce gas transport ability. A better understanding of the structure and transport of water and gas molecules is conducive to figure out the specific gasewater flow behavior and predict shale gas production. [ABSTRACT FROM AUTHOR]

Rapid urbanization and industrialization have heightened concerns about air quality worldwide. Conventional air purification methods, reliant on chemicals or energy-intensive processes, fall short in open spaces and in combating emerging pollutants. Addressing these limitations, this study presents a novel water-film air purification prototype leveraging the adhesion between low-curvature liquid surfaces and air convection friction. Uniquely designed, this prototype effectively targets toxic gases (e.g., formaldehyde, SO2, NO2) and particulate matter (such as PM2.5) while allowing continuous airflow. This research explores the adhesion and sedimentation capabilities of a low-curvature water solution surface under convection friction, reducing the surface energy to remove airborne pollutants efficiently. The prototype was able to reduce the initial concentration in a 30 m³ chamber within 180 min by 91% for formaldehyde, 78% for nitrogen dioxide (NO2), 99% for sulfur dioxide (SO2), and 96% for PM2.5. Experimentally validated indicators—decay constants, CADR, and purification efficiency—enable a comprehensive evaluation of the purification device, demonstrating its efficacy in mitigating air pollution. This innovative design, which is cost-effective due to its use of easily accessible components and water as the primary medium, indicates strong potential for large-scale deployment. This study points to an environmentally friendly and economical approach to air purification, shedding light on a promising direction for enhancing indoor air quality. Further optimization and exploration of diverse pollutants and environmental conditions will propel the practical applications of this pioneering technology.

Nuclear magnetic resonance (NMR) has been widely used in monitoring the imbibition behavior of oil/gas reservoirs, especially the T2 spectrum. Most T2 spectra are obtained from one dimensional (1D) NMR, but less research is related to T2 spectra from two dimensional (2D) NMR. Understanding the difference between these two methods helps take advantage of NMR in monitoring imbibition behavior. The main experiment is the imbibition behavior monitored by 1D and 2D NMR. Samples are tight sand from the Upper Paleozoic Taiyuan and Shihezi formations in the eastern Ordos Basin, which is full of natural gas, and the testing liquid is distilled water. The T2 spectra from 1D and 2D NMR increase with imbibition time, which shows that liquid increases among pore spaces. More peaks are in 2D T2 spectra than in 1D T2 spectra, which shows that 2D T2 spectra can differentiate more types of H1 proton signal. In dry state, a higher signal is 0.01–0.1 ms in 2D T2 spectra than in 1D T2 spectra, whereas the signal 0.1–1 ms is the opposite. This indicates that more signals are interpreted as short T2 values in 2D T2 spectra, and these signals mainly correspond to crystal water. In spontaneous imbibition with 30 min and 1 h, the signal of 0.01–0.1 ms in 2D T2 spectra is much higher than in 1D T2 spectra, because of the crystal water and water film effect. The signals in 1–10 ms are close between 1D and 2D T2 spectra, which indicates that imbibed liquid in this interval is interpreted the same. Overall, compared with 1D T2 spectra, 2D T2 spectra can differentiate more types of H1 proton and are suggested to monitor the imbibition behavior of tight reservoirs. [ABSTRACT FROM AUTHOR]

To solve the problem of high flow resistance of wet sludge pipeline, a rotary viscometer and a small self-made water film viscosity reduction device were used to explore the effects of the rheological properties of wet sludge, water-sludge ratio (WSR), wet sludge moisture content, wet sludge flow rate and water film temperature on water film viscosity reduction of wet sludge pipeline. The results show that the stress-time curve of wet sludge mainly goes through four stages, i.e. linear sharp increase stage, nonlinear increase stage, peak stage and gradual decrease stage. With the decrease of water content, the dynamic yield stress of wet sludge increases significantly. The greater the WSR, the more obvious the wet sludge pipeline viscosity reduction effect. When the WSR is 0.05, the viscosity reduction efficiency reaches 71.6% when the moisture content of wet sludge is 82.4% and the flow rate is 42.4 mL/min. When the WSR is 0.03, the turning point of viscosity reduction efficiency appears under these conditions. With the increase of wet sludge flow rate, the pipe shear stress and water film viscosity reduction amplitude increase, but the pipe shear stress increases more significantly, so the viscosity reduction rate decreases with the increase of wet sludge flow rate. Increasing water film temperature can improve the wet sludge viscosity reduction effect, and the lower the wet sludge moisture content, the more significant the improvement effect. Compared with water film at 18.5 °, the viscosity reduction of 70% wet sludge moisture content at 60.0 ° and WSR of 0.03 increases by 31.3%. [ABSTRACT FROM AUTHOR]

• Molecular modelling of complex nanoconfined water-CO 2 interactions in porous media. • In-depth analyses of water film and water bridge's generation and evolution. • Implications for complex nanoconfined water-CO 2 dynamics and geological carbon storage and utilization. Understanding the nanoconfined water-CO 2 interactions at the molecular scale is of great importance for the fluid transport in confined porous media. Here, a series typical water film and water bridge scenarios are determined, and the associated impacts on nanoconfined water-CO 2 interactions as well as the geological hydrocarbon recovery and CO 2 storage are investigated in nanopores. Our results confirm either in water film or water bridge scenarios, the competitive adsorptions of nanoconfined water and CO 2 reduce the adsorbed water amount and derive the new water bridge with CO 2 additions. Such a phenomenon indicates the substrate surface shifts from water-wet to partially CO 2 -wet, with lower fluid molecule diffusions and illite-water-CO 2 sandwich-structured adsorption layer. Overall, our work investigates the mechanism of CO 2 effects on distributions and aggregations of nanoconfined water molecules in nanopores, which also provides molecular-scale insights into the nanoconfined water-CO 2 interactions in the processes of geological CO 2 storage and utilization. [ABSTRACT FROM AUTHOR]

Layered structure in sand deposits is prevalent not only in reclaimed soils but also in natural alluvial soils. Liquefaction tests by a self-developed impact load system were carried out to investigate the excess pore water pressure (EPWP) generation and related liquefaction mechanism in layered sands, considering cases of uniform, two layered and interlayered sand columns respectively. Results show that the EPWP of saturated sands under impact loading presents two phases: transient response and steady-state response. For sands without interlayer, lower-permeability soil layer determines the rate of EPWP dissipation and lower permeability can result in smaller value of steady pore pressure but longer duration of that. For interlayered sands, presence of less permeable interlayer will prolong the total duration of pore pressure dissipation, and there is a significant "high pore pressure" sustained period during the dissipation stage of pore pressure, which is unfavorable for the liquefaction. Also, the presence of a less permeable interlayer within the sand deposit can lead to formation of water film underneath the interlayer. Besides, theoretical analysis of EPWP and water film under the same conditions are made, and it shows a good consistency between theoretical and test results, which verifies the rationality and reference value of the test analysis in this paper. • Dissipation mode of excess pore water pressure under different soil distribution conditions and sand types were analyzed. • Less permeable interlayer in sand deposit will result in long duration of"high EPWP "and water film, which were studied. • Theoretical analysis of excess pore pressure and water film was conducted and compared with test results for verification. [ABSTRACT FROM AUTHOR]

To manage energy-efficient indoor air quality, mechanical ventilation with a heat recovery system provides an effective measure to remove extra moisture and air contaminants, especially in bathrooms. Previous studies reveal that heat recovery technology can reduce energy consumption, and its calculation needs detailed information on the thermal performance of exhaust air. However, there are few studies on the thermal performance of bathroom exhaust air during and after showers. This study proposed a detailed thermal performance prediction model for bathroom exhaust air based on the coupled heat and mass transfer theory. The proposed model was implemented into the AccuRate Home engine to estimate the thermal performance of residential buildings with heat recovery systems. The time variation of the water film temperature and thickness on the bathroom floor can be estimated by the proposed model, which is helpful in determining whether the water has completely evaporated. Simulation results show that changing the airflow rate in the bathroom has little effect on drying the wet floor without additional heating. The additional air heater installed in the bathroom can improve floor water evaporation efficiency by 24.7% under an airflow rate of 507.6 m3/h. It also demonstrates that heat recovery can significantly decrease the building energy demand with the fresh air load increasing and contribute about 0.6 stars improvement for the houses in Hobart (heating-dominated region). It may be reduced by around 3.3 MJ/(m2·year) for the houses in other regions. With this study, guidelines for optimizing the control strategy of the dehumidification process are put forward.

Abstract The Sulawesi earthquake with a moment magnitude of M w 7.5 struck the Central Sulawesi region of the Sulawesi Island, Indonesia, on September 28, 2018. The epicenter of the earthquake was located in the mountainous region of Donggala Regency, in the neck of the Minahasa Peninsula in the Central Sulawesi Province of Indonesia. Although the epicenter was located in Donggala Regency, the greatest devastating effects were observed about 70 km south of the epicenter in the Palu Valley. The event was the first of its kind to cause large-scale flowslides simultaneously at four key locations such as Balaroa, Petobo, Jono Oge, and Sibalaya with extensive ground displacements ranging from several hundred meters to more than 1 km. This article reviews the field observations of geotechnical failures and infrastructure damage caused by liquefaction resulting from the shallow strike-slip earthquake at Palu City, Donggala Regency, and Sigi Regency. A geo-spatial analysis was performed on data collected from aerial drone imagery, along with portable dynamic cone penetration testing (PDCPT) in the field. The investigation revealed a highly stratified ground with alternating soil layers of varying permeability and very low bearing resistance at shallow depths. The investigation also helped in assessing the extent of damage caused by geotechnical failure to the residential infrastructures, irrigation structures, and roads. Graphical Abstract

In this study, the thickness of water film, which is frequently formed on compressor blade surface, was investigated. Simultaneously, its movement and extra torque demand were provided by a simulation model of the code. Having taken into account the transformation in blade's profile and the thickness feature of the films, the working medium characteristic transformation in compressor stage was analyzed. In addition, formation, development and movement of the water film on a compressor stage were simulated by using unsteady numerical methods in various water injected conditions. Movement characteristics of water droplets in cascade were investigated to understand the flow mechanisms responsible for water film formation process. The forming and the tearing process of water films, which formed on the blade surface, were analyzed at different injection conditions. In consideration of the "Scoop effect" in actual situation, the maximum quantity of injected water can reach 12 %. Results indicated that continuity and region of the film would be developed with the increment of droplet size and injection rate. It was also found that water film's tearing process brought about flow losses near blade surface due to the increment of surface roughness. [ABSTRACT FROM AUTHOR]

A series of experimental studies were conducted to explore the fluctuation characteristics of the water film under the air flow condition with the research background of the anti-icing system. The dynamic measurement of the water film on the surface of the aluminum-based plate was achieved using the digital image projection measurement technology. The influence of diverse wind speeds and Reynolds numbers on the average water film thickness, fluctuation intensity, and velocity of the liquid film was analyzed. The piecewise characteristics of the wind speed and Reynolds number for the fluctuation characteristics of the water film were analyzed innovatively. The fluctuation characteristics and formation principle of each stage were also examined. The results had a significant impact on establishing and modifying the mesoscopic models of aircraft icing to improve the design methodology of the anti-icing process. [ABSTRACT FROM AUTHOR]

This study presented a finite element model of radial tire–asphalt pavement interaction using ABAQUS 6.14 software to investigate the skid resistance properties of asphalt pavement under partial tire aquaplane conditions. Firstly, the pavement profile datum acquired by laser scanning were imported to Finite Element Analysis (FEA) software to conduct the pavement modeling. Secondly, a steady state rolling analysis of a tire on three types of asphalt pavements under drying conditions was carried out. Variation laws of the friction coefficient of the radial tire on different pavements with different pavement textures, tire pressures, and loads on the tire were examined. Subsequently, calculation results of the steady state rolling analysis were transmitted to dynamic explicit analysis, and an aquaplane model of a radial tire on asphalt pavements was built by inputting the flow Euler grids. The tire–pavement adhesive characteristics under partial aquaplane conditions are discussed regarding the aquaplane model. Influences of the thickness of water film, the texture of asphalt pavement, and the rolling speed of the tire on the vertical pavement-tire contact force are analyzed. It is found that the vertical contact force between open graded friction course (OGFC) pavement and tire is the highest, followed by stone mastic asphalt (SMA) pavement and dense graded asphalt concrete (AC) pavement surface. The vertical contact force between tire and pavement will be greatly reduced, even with increasing speed or water film thickness. As tire speed increases from 70 km/h to 130 km/h, the tire–pavement contact force is reduced by about 25%. Moreover, when the thickness of water film increases from 0 (dry condition) to 4 mm and then to 12 mm, the vertical contact force reduced 50% and 15%, respectively, compared with under the dry contact condition. This study provided a key theoretical reference for safe driving on wet pavements. [ABSTRACT FROM AUTHOR]

Water purification by non-equilibrium atmospheric pressure plasma has attracted much attention and is expected to be a next-generation method. However, general approaches to improve the energy efficiency of the water purification have not been revealed. Therefore, to investigate important factors for increasing its energy efficiency, we developed coaxial cylindrical plasma reactors where pulsed streamers were generated between a high-voltage electrode and running water film. To evaluate the performance of the plasma reactors, we measured hydroxyl (OH) radicals in solution based on a chemical probe method using disodium terephthalic acid (NaTA) and decolorized indigo carmine solution. Our experimental results showed that the production rate of the OH radicals was approximately 20 nmol/s and that the energy efficiency of the decolorization was on the order of 10 g/kWh. In addition, we found that controlling liquid flow based on the Coandă effect and introducing the intermittent operation of the streamer discharges to use post-discharge reactions increased the energy efficiency by a factor of approximately 3.5, which indicated that these approaches are effective to improve the performance of the water purification by plasma. [ABSTRACT FROM AUTHOR]

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Increasing the emission intensity of laser-induced breakdown spectroscopy (LIBS) is an effective way to improve the sensitivity of LIBS technology to elements analysis in liquid samples. In this work, the influence of the distance from lens to sample surface (DFLS) on the spectral emission of femtosecond laser-induced plasma of NaCl water film was studied by measuring Na atomic line. The results showed that the emission intensity of the spectral line presented the phenomenon of double peaks with an increase in the DFLS. The position for the highest spectral intensity was not geometric focal point of focusing lens, but was located in front of the geometric focal point. In addition, we carried out quantitative analysis on Na element with different concentrations, showing a calibration curve of Na element, and calculating limit of detection (LOD) and relative standard deviation (RSD) for different DFLSs. Subsequently, the changes in the LOD and RSD with the DFLS are discussed. With the increase of the DFLS, the LOD and RSD were greatly reduced. At the DFLS of 99.0 mm, the line intensity was highest, and the LOD and RSD were better. Therefore, it can be confirmed that femtosecond LIBS of water film can be optimized by changing the DFLS, the experiment shows great potential in real-time water quality monitoring.

Soil is typically unsaturated, with water films covering the soil particles playing a crucial role in soil mechanics, structure, and element transport. However, the unusual behavior of these water films and the underlying mechanisms are not yet fully understood. This study, which used molecular dynamics methods, sheds light on the distinct interactions between water films and clay surfaces under unsaturation. At the water-mineral interface, water molecules formed a layered structure, while they rearranged as a meniscus as the unsaturation extent increased. On the other hand, unsaturation had a significant impact on the location of water molecules at the water-vapor interface, but only a limited effect at the water-mineral interface. The water's orientational ordering and hydrogen bonding interactions were significantly affected by changes in relative humidity (RH). Based on the distance-dependent diffusion coefficient, the water molecules within the water film were classified into three types: WT1 (< 5 Å) had faster diffusivity at higher RH , WT2 (5–6 Å) had comparable diffusivity at any RH , and WT3 (> 6 Å) had faster diffusivity at intermediate RH. This classification was supported by the retention dynamics analysis. The specific behaviors mentioned above, which are associated with unsaturation, are closely linked to Na+ hydration. This is because the interaction between water and Na+ is more pronounced than the interaction between water and minerals or Cl−. The results indicate that unsaturation triggers specific adsorption behaviors of water films that cover the clay surfaces. These behaviors should be considered in interfacial processes and environmental engineering. [Display omitted] • Wettability and adsorption are significantly different in clay particles under non-saturation. • Three types of water molecules are classified according to the diffusion and retention behaviors. • "Transmission effect" passes from the water-vapor to the water-clay interface. • Cation hydration controls the specific performance of water films in unsaturated condition. [ABSTRACT FROM AUTHOR]

The CFD numerical study of the flash boiling phenomenon of a water film was conducted using an Euler–Euler method, and compared to the experiments on the flashing of a water film. The water film is initially heated at temperatures ranging from 34 to 74 ∘C (frim 1 to 41 ∘C superheat), and the pressure is decreased from 1 bar to 50 mbar during the experiments. This paper shows that the experiments could not be correctly modelled by a simple liquid/bubble model because of the overestimation of the drag force above the water film (in the gas/droplet region). The generalised large interface model (GLIM), however, a multi-regime approach implemented in the version 7.0 of the neptune_cfd software, is able to differentiate the water film, where liquid/bubble interactions are predominant from the gas region where gas/droplet interactions are predominant, and gives nice qualitative results. Finally, this paper shows that the interfacial heat transfer model of Berne for superheated liquids could accurately predict the evolution of the water temperature over time.

Corrosion and salt deposition problems severely restrict the industrialization of supercritical water oxidation. Transpiring wall reactor can effectively weaken these two problems by a protective water film. In this work, methanol was selected as organic matter, and the influences of vital structural parameters on water film properties and organic matter removal were studied via numerical simulation. The results indicate that higher than 99% of methanol conversion could be obtained and hardly affected by transpiration water layer, transpiring wall porosity and inner diameter. Increasing layer and porosity reduced reactor center temperature, but inner diameter's influence was lower relatively. Water film temperature reduced but coverage rate raised as layer, porosity, and inner diameter increased. Notably, the whole reactor was in supercritical state and coverage rate was only approximately 85% in the case of one layer. Increasing reactor length affected slightly the volume of the upper supercritical zone but enlarged the subcritical zone. [ABSTRACT FROM AUTHOR]

A two-stage electrostatic precipitator (ESP) with a reduced footprint, external ion-injection discharge, and water film on the collection plate was developed for long-term operation. For optimal particulate matter (PM) removal efficiency, the ionizer of the external ion injection system was fixed at a distance of 5 mm from the bias plate. Under these operating conditions, the 0.3-μm PM (PM0.3) removal efficiency was reduced to approximately 70% due to low migration velocity. The application of an additional collection plate extended the residence time of the charged particles in the electric field, which resulted in a removal efficiency exceeding 95%. However, long-term operation (675 min) of the two-stage ESP with external ion-injected discharge resulted in spark generation due to contamination of the ionizer, and the PM2.5 and PM10 removal efficiencies decreased linearly from 80.4% to 62.2% and 87.7% to 68.2%, respectively. Changing the ionizer to a pin shape with electrical specifications similar to those of carbon fibers resulted in water film formation on the collection plate. The PM2.5 and PM10 removal efficiencies remained at their initial levels for 120 min. The two-stage ESP with external ion-injected discharge operating with a water film is likely suitable for long-term operation in an industrial setting. [ABSTRACT FROM AUTHOR]

The steady, internal, and ultrasonic-generated water mist cooling in a uniformly heated vertical cylinder with evaporating subcooled water film has been investigated experimentally. The goal is to elucidate the effects of different operating parameters, viz. water mist concentration, carrier gas velocity, loaded heat flux, and flow orientation on the heat transfer rate and pressure drop characteristics. The experiments were performed in a turbulent flow regime over a range of Reynolds number (from 6000 to 18000) using air as the carrier fluid. Compared with the cylinder without water mist, the results showed that using water mist as a coolant increases the Nusselt numbers along the cylinder, high Nusselt numbers are obtained by suspending the high-water mist and it was about 224% for heat flux q=1.56 kW/m². The results also showed that the local Nusselt number rapidly decreases as the heat flux increases, this decreasing in the Nusselt number was the most at high heat flux q=4.81 kW/m², in which the water film early breakdown and the breakdown point gets closer to the entrance region. In addition, a new empirical correlation of the heat transfer rate was proposed to estimate the real benefits in using water mist of the enhanced cylinder. [ABSTRACT FROM AUTHOR]

The results have been presented of the theoretical and experimental research of the ignition processes of single drops of coal–water fuel (CWF). Their surface is covered by a water film. The temperature of the environment Tehas also been recorded and the main characteristics of the process — the times of complete evaporation of the water film (tewf)) and the ignition delays (tign). The errors in determining Tehave not exceeded 5%.According to the results of the detailed analysis of the video recordings of the investigated process of ignition, the mathematical models have been developed. They describe the interrelated complex of the thermophysical and thermochemical processes. The approximate analytical solutions of the multistage nonlinear problem of ignition of a coal–water particle have been obtained using the asymptotic procedures.According to the results of the experimental and theoretical studies, it has been established that the thickness of an aqueous film is one of the parameters determining the conditions and characteristics of the CWF ignition. Moreover, under the conditions of the experiments it has been established that the characteristic evaporation time of the near-surface layer can be from 45 to 60% of the total induction period. They depend on the thickness of the film.