Study on the evolution of wind-blown sand and gravel flow erosion resistance of aeolian sand concrete in cold regions and the coupling mechanism of freeze-thaw cycles: Laboratory tests and numerical simulation

With the rapid development of high-head hydraulic resources in the southwest of China, the problem of sediment erosion of large Pelton turbines has attracted increasing attention. Based on the design data of a 500 MW single-unit Pelton turbine of a hydropower station, a model of a 400 mm circular diameter Pelton turbine has been developed. The SST k-ω turbulence model, the volume of fluid method, and a Lagrangian equation for particle motion are used to analyze the distribution of sediment concentration and velocity on the surface of the injector. A mathematical model of sediment erosion of a Pelton turbine injector is established on the basis of the sediment erosion test and the results of internal flow simulation. It is found that the maximum erosion rate of the needle test block is 0.80 μm/h, and the erosion rate of the nozzle is 2.50 μm/h. The results of this study provide a theoretical basis and technical guidance for the prediction of sediment erosion in real large Pelton turbines.

The barrier lake formed by the high-speed landslide that blocks the river typically faces a high risk of failure due to its loose and fragmented structure, high permeability, and weak erosion resistance. Based on the characteristics of this type of landslide dam, this paper proposes a new method for emergency rescue of barrier lake outburst by grouting inside the dam. Through 16 groups of experiments, the effects of three key parameters—grouting depth, grouting point arrangement, and layout position—on outburst control were systematically studied, and the mechanism by which grouting technology reduces outbursts was clarified. The results show that the inhibitory effect of the grouting consolidation body on particle initiation and transport, as well as the water-blocking effect caused by guiding water flow around, can fundamentally explain the good flood detention performance of grouting technology by reducing the flow section, limiting breach widening, and narrowing water flow. The depth and position of grouting are key factors for the peak clipping effect. The grouting point should be accurately positioned in the key area subjected to water flow erosion (on the breach side), allowing for a more effective blocking effect with fewer grouting points. When the grouting points are concentrated on the breach side, there is an optimal threshold for the number of grouting points, and benefits diminish after this limit is exceeded. The results can be used for emergency rescue and engineering measures related to the landslide dam.

Abstract Small‐diameter vascular grafts are prone to thrombosis and stenosis mainly due to inadequate endothelialization. The current in vitro endothelial cells (ECs) seeding methods are time‐consuming and insufficient to resist blood flow erosion, which limited the application of pre‐endothelialized grafts. Herein, human induced pluripotent stem cell‐derived ECs (hiPSC‐ECs) are modified with azide group via metabolic glycoengineering. Then, these cells can achieve complete endothelial coverage on the lumen surface of Dibenzocyclooctyne (DBCO)‐functionalized polycaprolactone (PCL) grafts via click reaction at 2 h, which is currently the fastest method. Transcriptomic analysis reveals upregulated cytoskeletal/ junctional genes and suppressed inflammatory pathways, suggesting enhanced endothelial barrier function. In the mouse carotid artery replacement model, the click‐endothelialized exhibits ≈64% cell retention at 7 days and achieve a 100% patency at 30 days, which is both superior to the traditional seeding group (retention rate ≈ 2%; patency rate = 33.3%). The implanted hiPSC‐ECs accelerate host endothelial regeneration and attenuate inflammation response of grafts. At 90 days, the regenerated ECs and smooth muscle cells exhibited a tissue structure similar to that of a natural artery. The click reaction‐mediated seeding strategy provides a rapid and stable pre‐endothelialization approach, which may be promote the application of pre‐endothelialization grafts, especially for emergency vascular surgery.

Erosion caused by sediment-laden flow significantly affects the efficiency and durability of Francis turbines. In this study, the Euler–Lagrange multi-phase flow model was employed to simulate solid-liquid two-phase flow with different sediment particle sizes to analyze erosion characteristics in turbine components. The results show that the maximum erosion rate of the runner blades is positively correlated with particle impact velocity, confirming that impact velocity is the dominant factor influencing local material removal. The total erosion rate of the runner blades, guide vanes, and draft tube corresponds closely with vorticity, indicating that vortex-induced flow separation accelerates particle–wall collisions and intensifies erosion. Both vorticity and erosion exhibit a nonlinear variation with particle size, reaching a minimum at 0.05 mm. These findings establish clear qualitative and quantitative relationships between erosion and key flow parameters, providing theoretical guidance for understanding and mitigating sediment-induced wear in Francis turbines.

Simulation study on gas-liquid-solid multiphase flow characteristics and erosion mechanism in a natural gas bend

Abstract P‐wave velocity profiles from seismic refraction reveal deep critical zone (CZ) architecture along profiles hundreds of meters long. However, extrapolating local velocity measurements to infer CZ architecture at regional scales (1–20 km 2 ) remains challenging. Here, we present a strategy that transforms seismic observations from individual profiles into maps of CZ architecture spanning tens of square kilometers. Data from 15 seismic refraction profiles (approximately 6.6 km total length) collected in weathered crystalline rocks of the South Carolina Piedmont, USA, revealed approximately 400,000 m 2 of deep CZ architecture. Using casing depths from four boreholes, we show that the boundary dividing saprolite and fractured rock corresponds to a velocity of 1,870 m/s. Using velocity measurements from an outcrop within the survey area, we identify the bedrock velocity as 4,550 m/s. These velocities define a three‐layer CZ structure comprising soil and saprolite, fractured bedrock, and unweathered bedrock. We developed an empirical relationship between CZ structure and minimum and maximum principal curvatures, enabling prediction of CZ architecture over approximately 17 km 2 . The correlation between seismically inferred CZ structure and principal curvatures at our study site suggests that curvature metrics can be used to predict CZ structure at larger scales in crystalline terrains under subtropical climates. However, the empirical relationship struggled to predict CZ structure where landscape curvatures were near zero, suggesting that other variables likely contribute to local heterogeneity. Given that curvature is an important variable for erosion and groundwater flow, our results suggest it could be a promising metric for predicting CZ structure.

Numerical study on the evolution of cavitating flow and collapse-induced erosion characteristics in high-speed hydraulic tunnel☆

Abstract Channel erosion not only amplifies debris‐flow magnitude and impact but also reshapes local geomorphology. However, the destructive and infrequent nature of debris flows makes in situ monitoring of channel‐bed erosion processes and flow characteristics challenging. Here, we investigate seismic signals for monitoring erosion‐driven geomorphic changes, using data from 18 well‐documented debris flows at Illgraben, Switzerland, between 2019 and 2023. We find that integrated seismically derived impact forces over each event correlate with channel‐bed elevation changes, revealing erosion thresholds. Seismic peak frequencies correlate with absolute channel‐bed elevations at seismic source regions, reflecting changes in wave propagation paths due to erosion. The correlation is evident, with peak frequency shifts exceeding 15 Hz while channel‐bed elevation changes were under 4 m during the 5‐year period. These findings demonstrate the capacity of seismic signals to characterize debris‐flow erosion and track absolute channel‐bed elevations, offering new insights into geomorphic processes.

In a series of exogenous and endogenous processes that cause enormous damage almost all over the world, land erosion and torrential flows occupy a special place. Torrential flows are formed practically unnoticed and represent a mixture of a large amount of eroded material from mountainous and hilly areas, which, together with water, flows down the ravines formed at a high speed into the lower parts. These streams, which in dry weather have very little flow or their beds are completely dry, in a short period of time destroy everything in front of them, from bridges, roads, to other buildings. They fill canals and agricultural land with silt, and often endanger populated areas, often with human casualties. A true example of the above was witnessed in the destruction of settlements in the municipality of Konjic and municipality of Jablanica in October 2024, where torrential rains caused huge human losses and material damage in a few hours.

Abstract Large‐scale photovoltaic (PV) panel installations may significantly affect local hydrological processes, especially in hilly and mountainous regions. However, there is large uncertainty in assessing the hydrological impacts of PV power stations, as the effects of PV panel arrays on overland flow and rill erosion processes in hillslopes have been overlooked. This study quantitatively investigated the interactions between overland flow, soil loss, and rill development influenced by a PV panel array through artificial rainfall experiments on a loess slope with bare surface. The dynamics of overland flow and soil erosion processes in the slope with a four‐panel PV array were compared to a control slope. In the experiments, it was observed that the rill development in the PV slope was largely inhibited. The experiment results demonstrated that, under varying rainfall intensities, the soil erosion mass and the peak erosion rates of the PV slope was 39.7%–64.1% and 38.0%–52.5% less than the control slope, respectively. The reason for this soil erosion mitigation might be that the PV panel array attenuated the impact of rainfall by blocking raindrops, and diminished the overland flow velocity as well as its concentrating movement into rills. These reduced the erosivity of overland flow and decreased soil particle detachment and movement in the slope, which ultimately inhibited rill development and erosion. These findings provide a quantitative basis for accurately assessing the early stage environmental impact of PV power stations, suggesting that large PV installations in arid and semi‐arid regions may reduce initial soil erosion.

Pumped storage power stations on sediment-laden rivers are highly susceptible to erosion damage on the surfaces of major flow-passing components due to sediment particles. In this study, an Euler–Lagrange model is employed to numerically investigate the sand–water flow characteristics and erosion prediction of a pump–turbine under hump-region conditions, focusing on crest, trough, and high-flow operating points. The results show that the internal flow of the pump–turbine undergoes significant changes in the hump region. Under low-flow conditions, flow separation, backflow, and local vortex phenomena occur inside the runner. Vortices in the runner passages tend to entrain sediment particles, resulting in a reduction in particle velocity. With increasing sand–water flow rate, a pronounced velocity difference develops on both sides of the blades, with the maximum difference reaching 20 m/s. The average erosion rates on the runner blades and the end faces of the guide vanes are 4.2 × 10−8 and 3.5 × 10−8 kg/(s·m2), respectively. The cutting erosion patterns on the blade surfaces coincide with the trajectories of the water flow vortices, and the erosion rate distribution on the guide vane end faces shows a high degree of consistency with the distribution of sand–water vortices.

Asthenospheric flow and lithospheric erosion driving the outward growth of the northeastern Tibetan Plateau.

Abstract Gullies are actively changing landforms on planet Mars. The prevailing hypothesis, supported by a suite of different studies, states that present‐day activity in these gullies is caused by fluidized granular flows driven by the sublimation of seasonal ice. However, the long‐term formation process of gully landscapes is a contentious issue as water‐driven debris‐flow processes could easily explain erosion. In contrast, we do not know if ‐driven granular flows can cause a significant amount of erosion. In this study, we conducted flume experiments investigating the flow dynamics and erosion capacity of ‐driven granular flows under different substrate and flow settings. Our experiments show that ‐driven granular flows under Martian conditions are efficient erosive agents, which can erode and entrain large volumes of unconsolidated material in various environmental (i.e., substrate and flow) settings. In general, erosion and entrainment enhance the mobility of ‐driven flows. However, the frost and thermal conditions of the slopes and the flow composition determine the erosion efficiency of these flows. Finally, based on terrestrial debris‐flow erosion theory we estimate that collisional forces at the base of ‐driven flows can also cause erosion of more consolidated material such bedrock, permafrost or Latitude Dependent Mantle.

Scree soil surface flow erosion: characteristics and gravel mulch technology

The soil aggregate stability index is one of the critical indicators of soil physical quality, primarily related to the soil's ability to absorb water into the soil and the soil's resistance to rainwater splashing and surface flow erosion in the soil erosion process. The study aimed to determine the soil aggregate stability index class criteria using the dry and wet sieving methods on the OSK 10701 sieve type and to identify the stability of soil aggregates on agricultural land, plantations, and forests around the IPB Dramaga campus. The transformation of the soil aggregate stability class criteria from the conventional sieve to the OSK 10701 sieve types gave excellent results with a coefficient of determination (R2) of 0.89. The soil aggregate stability index differs significantly between soil types and land uses. Podsolic Jasinga has a higher aggregate stability index than Podsolik Dramaga, Regosol Dramaga, and Latosol Dramaga in the upper layer (0-20 cm) and the lower layer (20-40 cm). Forests have a better aggregate stability index than conservation agricultural land, conventional agricultural land, rubber plantations, and oil palm plantations. The difference in stability index between land uses is closely related to soil organic matter contents. Although the soil is denser/more compact, the soil in oil palm and rubber plantations has a lower stability index and is classified as unstable.

Horizontal transport characteristics of microplastics under simulated hydrodynamic conditions.

The leakage flow induced by the end clearance of guide vanes in Francis turbines significantly impacts unit efficiency and sediment erosion characteristics. Existing numerical studies often neglect the influence of guide vane clearance, leaving the mechanistic role of clearance flow in sediment erosion characteristics poorly understood. This study systematically investigates the influence of four clearance schemes (ranging from 0 to 2.6 mm) on the flow dynamics and erosion patterns in a high-head turbine using a numerical simulation approach for solid–liquid two-phase flow. The results reveal that increasing the clearance not only markedly reduces hydraulic efficiency (with efficiency declines of 0.4%, 2.0%, and 4.0% for clearances of 0.52 , 1.82 , and 2.6 mm, respectively) but also transforms the leakage vortex structure in the guide vane domain from a single elliptical form into an intensified Y-shaped configuration. Sediment particles undergo two 90° deflections within the clearance, leading to pronounced erosion zones near the guide vane pivot, trailing edge, and upper/lower cover plates, with erosion severity escalating alongside clearance enlargement. The evolution of leakage vortices distinctly alters erosion distribution, causing the erosion regions on the cover plates to coincide with the vortex projection areas. Notably, the impact velocity and erosion rate at the lower ring side of the blade suction surface leading edge increase substantially with larger clearances, indicating that excessive clearance dimensions critically exacerbate erosion damage in this region. The study establishes quantitative relationships between guide vane clearance size, efficiency loss, vortex evolution, and erosion characteristics, offering valuable insights for elucidating sediment-induced erosion mechanisms and optimizing anti-erosion designs in Francis turbines. Abbreviations: PAT: pump-as-turbine; CFD: computational fluid dynamics; FFT: Fast Fourier Transform; Lff: leakage flow factor; SST: shear stress transport; t: time; mp : particle mass; up : particle velocity; Fd : drag force; Fb : Buoyancy Force; Fg : Gravitational Force; Fv : virtual mass force; Fp : pressure gradient force; Fx : sum of other external forces; R-R: Rosin-Rammler; Yd : mass fraction of particles exceeding size d; dm : mean particle diameter; n: distribution exponent; d: particle diameter; Vf : volume fraction; η: hydraulic efficiency; Nn : number of nodes; fr: random error; fs: systematic error; fη: relative uncertainty of the hydraulic efficiency measurement; H: water head; Ra: roughness of the specimen surface; NER: normalized erosion rate; E90: reference erosion rate at 90° impact angle; V: particle impact velocity; Vref: reference velocity; dref : reference diameter; k 2 : velocity exponents; k 3 : diameter exponents; f(γ): impact angle function; Hv: Vickers hardness of wall material; n 1, n 2: empirical constants for the angle function; C: clearance; QL : leakage flow rate; S-S: Swirling strength; SV: sand velocity; ER: erosion rate; SVf: sand volume fraction; Vi: impact velocity.

The study investigates the complex dynamics of mudflows on the northeastern slope of the Greater Caucasus in Azerbaijan, emphasizing their role as a destructive geomorphological factor influencing river basin evolution. Mudflows are shown to be closely linked with surface erosion processes intensified by continuous tectonic uplift and climatic changes. The research integrates long-term observational data, hydrological monitoring, and field expeditions up to 2024, employing a multidisciplinary methodology combining cluster analysis, geographical determinism, and GIS-based spatial modeling. It reveals that intense frost weathering, coupled with increased rainfall intensity (up to 3 mm/min), significantly accelerates surface denudation, producing vast quantities of loose sediment available for mobilization during extreme rainfall events. The lithological composition of the region, dominated by weakly consolidated sedimentary rocks, further enhances susceptibility to erosion and debris flow formation. Analysis of suspended sediment discharge across 24 monitoring stations highlights a strong correlation between gully network density and erosion intensity, with surface erosion rates ranging from 0.003 to 0.13 mm/year during five-hour mudflow events. The impact of global climate change is also evident, with rising temperatures accelerating glacial retreat and shifting rainfall patterns, thereby increasing the frequency and magnitude of mudflow occurrences. Vegetation cover emerges as a critical mitigating factor, reducing erosion through root reinforcement and interception of rainfall. The findings underscore the need for integrated risk assessment frameworks and sustainable land-use planning strategies to address the growing threat posed by mudflows to infrastructure, agriculture, and human settlements. This work provides a scientific foundation for predicting future mudflow activity and developing targeted mitigation measures tailored to the unique physical-geographic conditions of the region.

The intelligent operationand maintenance of gas injection andproduction in salt-cavern compressed air energy storage means adjustingor optimizing the gas injection and production plan in real-time accordingto the volume of injected and produced gas under the premise of safetyand economy. The key is how to optimize the wellbore allocation planfor gas injection and production. Therefore, based on the improvedrandom forest algorithm and the gas injection and production conditions,this paper establishes an improved random forest algorithm to obtaina set of wellbore allocation plans with a priority order. In combinationwith the cutting particle motion model and the pressure-flow predictionmodel for gas injection and production, constraints are set on thecutting-carrying size, erosion flow rate, and minimum injection andproduction flow rate. An intelligent allocation solution algorithmfor injection and production wellbores of salt-cavern compressed airenergy storage under the dual constraints of safety and economy isestablished, and a case analysis is conducted to prove the necessityof the model. Furthermore, the impacts of economic constraints, totalgas injection and production volume, wellbore diameter, and injectionand production media on the wellbore allocation for injection andproduction are explored. The research results show that ① Thewellbore allocation results obtained from the model established inthis paper can avoid safety hazards and economic losses during thegas injection and production process, enabling the gas storage reservoirto operate more stably and efficiently. ② The ground cuttingtreatment capacity has a significant impact on the injection and productionwellbores, and it is necessary to select appropriate equipment forground cutting treatment. ③ As the total planned volume ofgas injection and production increases, more injection and productionwells are required. The maximum flow rate of a single wellbore inthe overall gas injection condition decreases, and the maximum flowrate of a single wellbore in the overall gas production conditionalso decreases. Moreover, the larger the size of the injection andproduction wellbores, the higher the priority of their allocation.The wellhead pressure is not affected by the above factors. ④Gases with a relatively low gas density as the injection and productionmedium will require more injection and production wells during theinjection and production process. The flow rate of a single injectionand production well is larger; the cutting-carrying size is larger,and a higher wellhead pressure is needed. The research results canprovide theoretical guidance for the accurate prediction of the intelligentallocation method of injection and production wellbores in salt-caverncompressed air energy storage and contribute to ensuring the safe,economic, and efficient operation of salt-cavern gas storage reservoirsin China.