Erosion Characteristics Research Articles

Blanket bogs exhibit significant alterations to physical properties as a result of temporary track removal or abandonment

AbstractTemporarily consented tracks made from high‐density polyethylene (HDPE) mesh have been used to mitigate both the physical and ecological impacts on peatlands from low‐frequency vehicle usage. However, the impacts of mesh track removal or abandonment at the end of the consented period remain poorly understood. Over a 2‐year period, we studied replicate sections of abandoned mesh track which, at the start of the experiment, had been unused for approximately 5 years, on a UK blanket bog. Some sections were removed (using two treatment methods – vegetation mown and unprepared), whereas others were left in situ. Metrics were compared both between treatments and to undisturbed reference areas. Significant differences in surface soil moisture were found between abandoned and removed tracks depending on season. Control areas had higher volumetric soil moisture than track locations. Compaction was significantly higher across all track locations in comparison to controls (p < 0.001), but rarefaction was not recorded post‐removal, suggesting long‐term deformation. Overland flow events were recorded in rut sections for a mean of 16% of the time, compared to <1% in control areas. Sediment traps on the tracks collected 0.406 kg compared to 0.0048 kg from the control traps, equating to a per trap value of 7.3 g from track samplers and 0.17 g from control samplers. Erosion and desiccation features occurred on both removed and abandoned track sections. Both abandonment and removal of mesh tracks have a wide range of impacts on the physical properties of peatlands, suggesting that only where access is a necessity should such a track be installed.

Measuring Erosional and Depositional Patterns Across Comet 67P's Imhotep Region

AbstractComet 67P/Churyumov‐Gerasimenko displays a pronounced hemispherical dichotomy in surface morphology, where the southern hemisphere exhibits more erosional features than the northern hemisphere due to receiving much greater solar radiation. Consequently, it is generally assumed that particles are ejected from the southern hemisphere through sublimation and a significant fraction eventually descends as airfall, covering the northern terrains. To investigate this south‐to‐north material transfer during the comet's perihelion passage, we used photoclinometry to measure material redistribution within its most extensive smooth terrain deposit around the Imhotep region. However, our findings do not align with this expected trend. Instead, we show that local‐scale processes substantially impact the erosion and accumulation of material, with one area experiencing net erosion while another nearby region, just a few dozen meters away, sees sediment buildup. Our analysis underscores the complex interplay of processes shaping Comet 67P's surface and likely comets more generally.

The influence mechanism of asymmetric distribution characteristics of erosion in the injector of Pelton turbines

The influence mechanism of asymmetric distribution characteristics of erosion in the injector of Pelton turbines

Design of a high-speed cavitation hydrodynamics test system

Due to the high sediment content in rivers in China and the relatively high concentration of “gas core” in water, cavitation of hydraulic machinery is likely to occur at high speeds, leading to a series of problems such as reduced efficiency of hydraulic machinery, intensified vibration and material erosion. To carry out the study of cavitation erosion, a test system (hereinafter referred to as the cavitation water tunnel) suitable for the basic study of cavitation dynamics at high velocity is designed in this paper. The whole system includes a circulating loop structure, which mainly consists of a suction chamber, contraction rectifier, and test section. The test section is convenient for observing different types of cavitation flow fields inside and the highest test velocity in the test section can exceed 35 m/s. A water-gas separation chamber is designed to collect bubbles over 100 microns to ensure that the inlet of the test section is not affected by cavitation. The functions of the test system include basic experiments such as flow field characteristics, cavitation dynamics, acoustic characteristics, and cavitation erosion characteristics around hydrofoils/blades, which can provide test conditions for the study of high-speed hydrodynamic characteristics such as pumps/turbines, propellers and underwater vehicles.

Effect of multiple factors on sediment erosion characteristics of hydro turbine materials

Hydraulic turbines on sediment-laden rivers suffer from cavitation-silt erosion. This study conducted cavitation-silt erosion tests on three materials (06Cr16Ni5Mo, Q355B, 06Cr20Ni11) with different sediment concentrations and impact velocities using a rotating disk facility, and used a scanning electron microscope (SEM) to observe the cavitation-silt erosion characteristics of the materials. The results show that the cumulative weight loss of all materials continuously increases with the sediment concentration and impact velocity rises. The weight loss of 06Cr16Ni5Mo is the lowest, and 06Cr20Ni11 is the highest. As the impact velocity rises, the cumulative weight loss increases exponentially. As the sediment concentration rises, there are obvious scour marks and fatigue spalling on the material surface. As the impact velocity rises, the size and depth of micro-cutting marks and cavitation pits increases. Due to the lower surface hardness of 06Cr20Ni11, the deep platelet pits appear on the material surface.

Experimental and numerical study on the breaching mechanisms of landslide dams with non-uniform structures

Landslide dams often exhibit non-uniform structures due to the rapid and dynamic accumulation of various types of landslide materials. These variations in dam composition significantly impact breach progression, causing significant errors in current model tests and numerical simulations with uniform structure assumptions This adversely affects peak flow predictions and decisions related to risk prevention and control. This study conducted a series of flume tests to examine the influence of non-uniform structures on the failure mechanisms of landslide dams. A 3D dam breach model was used to replicate these flume experiments and obtain more detailed information. Large Eddy Simulation (LES) captures the hydraulic features of dam-break flow, while equilibrium equations model morphological changes in landslide dams amid complex terrains using suspended and bed load transport. The findings indicate that in a uniform dam, the presence of coarse particles shifts erosion characteristics from layered erosion to step-pool development. Furthermore, as the content of coarse particles increases, the number of steps also rises. In the vertically non-uniform structure, the upper layer affects the formation of the breach, the middle layer affects the dam break and the breach flow, and the bottom layer affects the remaining dam height. The presence of an armor layer results in a higher water level and accelerates breach formation with a larger breach flow. In the horizontally non-uniform structure, the upper part of the overflow side is the core area of the breach, the lower part of the overflow side and the upper part of the opposite side affect the downcutting and widening rates of the breach, respectively. Preferentially, the breach tends to develop towards the relatively weaker of the two sides.

Experimental Investigation of the Evolution Process of Suspended Pipelines through River Bottoms under Unsteady Flow Conditions

One of the major geological hazards that can cause harm to long-distance oil and gas pipelines are water-induced disasters. These disasters are quite common and widespread. Pipelines that cross river channels are at a higher risk of facing damage due to flood-induced erosion. To shed light on the evolution pattern of riverbeds adjacent to pipelines under the influence of unsteady flow conditions, a flume model test was conducted, and the underlying mechanisms of local scour were elucidated. The experimental results demonstrate that pipelines are more susceptible to suspension during flood conditions. The suspension process of pipelines under flood conditions could be broadly divided into five stages. In comparison to constant flow conditions, the evolution process of local scour and the suspension of pipelines under unsteady flow lacked the erosion pit expansion stage, and the scour duration was shorter. Each stage exhibited distinct erosion characteristics, and both the peak flow rate and the number of flood peaks significantly impacted the maximum range and depth of the erosion pit. During pipeline-laying projects, selecting a covering layer with a larger particle size can enhance the erosion resistance of the riverbed around the pipeline. The study of the local erosion process of underwater crossing pipelines under unstable flow conditions can provide a reference for pipeline engineering design and riverbed pipeline protection strategies.

Surface sediment erosion characteristics and influencing factors in the subaqueous delta of the abandoned Yellow River Estuary

Estuarine deltas play a critical role in the interaction between the ocean and land and serve as the primary location for the deposition of terrestrial organic carbon and pollutants. However, many deltas are increasingly at risk of erosion due to natural processes and human activities. In particular, abandoned estuarine deltas are extremely prone to erosion in the absence of sediment replenishment. The erosion of sediment in these deltas is crucial in comprehending the evolution of delta erosion as it directly impacts coastal geomorphology, ecological environments, geochemical cycling, and carbon sequestration dynamics. Therefore, determining accurately the erosion characteristics of estuarine deltaic sediments is essential for assessing and managing these evolving coastal systems. Therefore, this study conducted erosion experiments on undisturbed sediment samples collected from the subaqueous delta of the abandoned Yellow River Estuary (Old Qingshuigou Estuary) utilizing the UMCES-Gust Erosion Microcosm System. The aim was to reveal the spatial distribution characteristics of sediment erodibility and explore the erosion process, characteristics, and influencing factors of the surface sediments in the area. Erosion characteristics exhibited a spatial distribution pattern of increased erodibility in nearshore sediment and reduced erodibility in offshore sediments. The critical erosion shear stress of surface sediments ranged from 0.2 to 0.68 N/m2, while the erosion rate increased linearly with an increase in erosion shear stress and reached a maximum value of 2.119 g/m2 s, suggesting that nearshore sediments exhibited strong erodibility. Furthermore, the erosion characteristics exhibited a strong correlation with the type of sediment. Silt exhibited surface erosion and Type I erosion (depth-limited erosion), whereas silty sand primarily underwent volume erosion and Type II erosion (steady-state erosion). Particle size characteristics played a crucial role in influencing erosion. Additionally, our results revealed that the effective particle size of sediment aggregates and the scale effect of turbulence were also important factors that affected sediment erosion characteristics. These findings not only enhance our understanding of the erosion characteristics of silty sediments but also provide valuable parameters for sediment transport models in large river deltas such as the Yellow River Delta, thus facilitating the release of buried organic carbon and heavy metals from estuaries.

Numerical simulation on sand sedimentation and erosion characteristics around HDPE sheet sand barrier under different wind angles

Numerical simulation on sand sedimentation and erosion characteristics around HDPE sheet sand barrier under different wind angles

Effects of axial misalignment welding defects on the erosive wear of natural gas piping

When considering solid particles in the pipe and axial misalignment weld defects in natural gas transmission systems, changes in the flow field due to structural differences can lead to various erosion characteristics in the bends. To investigate the erosion process within the bend, the computational fluid dynamics (CFD) - discrete phase model (DPM) method to develop a bend model with axial misalignment weld seam defects was employed. The erosion distributions of a bend with an axial misalignment weld were investigated under various transport parameters, bend orientation, axial misalignment height, and particle incidence angle. The results indicated that the erosion rate of the outermost elbow increases with the increase of the height of the axial misalignment weld on the outside of the bend pipe. When the axial misalignment height ranges from 1 mm to more than 5 mm, the difference in the maximum erosion rate escalates from 7 % to approximately 30 %. When the length of the inlet straight pipe is shorter, an increased incident angle intensifies the erosion effect and vice versa. This research can provide a reference for field construction work involving defective natural gas pipe bends.

Erosion Characteristics and Flashing Flow of High-differential-pressure Control Valves: A Numerical Study using an Erosion-Coupled Dynamic Mesh

To address the issue of erosion in the control valves of blackwater flash systems in the coal chemical industry, this study investigates the dynamic erosion characteristics of one such control valve. Computational fluid dynamics is employed to compare the results obtained with a static mesh and an erosion-coupled dynamic mesh, and the valve erosion is investigated by analyzing the erosion rate, the particle impact velocity, trajectories and angle. Moreover, the relationship between the deformation caused by erosion and the dispersion of the flash vapor phase in the valve is studied, focusing on the flow resistance coefficient. The results indicate that over a period of 9 × 106 s, the impact velocity and subsequent collisions of particles reduce, and the impact angle decreases with the accumulated deformation of the valve core. Notably, the valve core is influenced primarily by the cutting that results from low impact angles, leading to a substantial decrease in the overall erosion rate of the valve, amounting to a reduction of 56.4%. The region facing the flow is at significant risk of erosion, and as the opening decreases, the erosion zone extends gradually to the annular region of the valve core and valve head, leading to increased erosion deformation. Furthermore, as the flow resistance coefficient decreases, so does the vapor volume fraction inside the valve. This study provides a theoretical basis for predicting faults and developing online monitoring solutions for high-differential-pressure control valves in blackwater flashing systems.

Flow field, sedimentation, and erosion characteristics around folded linear HDPE sheet sand fence: Numerical simulation study

Flow field, sedimentation, and erosion characteristics around folded linear HDPE sheet sand fence: Numerical simulation study

Research on Leading Edge Erosion and Aerodynamic Characteristics of Wind Turbine Blade Airfoil

Research on Leading Edge Erosion and Aerodynamic Characteristics of Wind Turbine Blade Airfoil

Are glenoid retroversion, humeral subluxation, and Walch classification associated with a muscle imbalance?

IntroductionThe etiology of humeral posterior subluxation remains unknown, and it has been hypothesized that horizontal muscle imbalance could cause this condition. The objective of this study was to compare the ratio of anterior to posterior rotator cuff muscle and deltoid volumes as a function of humeral subluxation and glenoid morphology when analyzed as continuous variable in arthritic shoulders. MethodsThree hundred and thirty-three (273 arthritic and 60 healthy controls) CT-scans of shoulders were included in this study and were segmented automatically. For each muscle, the volume of muscle fibers without intra-muscular fat was then measured. The ratio between the volume of the subscapularis and the volume of the infraspinatus + teres minor (AP ratio) and the ratio between the anterior and posterior deltoid (APdeltoid) were calculated. Statistical analyses were performed to determine whether a correlation could be found between these ratios and glenoid version/ humeral subluxation/glenoid type in the Walch classification. ResultsWithin the arthritic cohort, no statistically significant difference was found between the AP ratio between A and type B glenoids (1.09 ± 0.22 versus 1.03 ± 0.16 p=0.09), between A and D type glenoids (1.09 ± 0.22 versus 1.12 ± 0.27, p=0.77) nor between the A and C type glenoids (1.09 ± 0.22 versus 1.10 ± 0.19, p=1). No correlation was found between AP ratio and glenoid version/humeral subluxation (rho =-0.0360, p=0.55; rho = 0.076; p=0.21). The APdeltoid ratio of type A glenoids was significantly greater than that of type B glenoids (0.48 ± 0.15 versus 0.35 ± 0.16, p< 0.01), and type C glenoids (0.48 ± 0.15 versus 0.21±0.10, p < 0.01) but not significantly different from the APdeltoid ratio of type D glenoids (0.48 ± 0.15 versus 0.64 ± 0.34, p=1). When evaluating both healthy control and arthritic shoulders, moderate correlations were found between APdeltoid ratio and glenoid version/humeral subluxation (rho=0.55, p<0.01; rho=-0.61, p<0.01). ConclusionThis in vitro study supports the use of a software for fully automated 3D reconstruction of the four rotator cuff muscles and the deltoid. Compared to previous two-dimensional CT-scan studies, we did not find any correlation between AP muscle volume ratio and glenoid parameters in arthritic shoulders. However, once deformity occurred, the observed APdeltoid ratio was lower with Type B and C glenoids. These findings suggest that rotator cuff muscle imbalance may not be the precipitating etiology for the posterior humeral subluxation and secondary posterior glenoid erosion characteristic of Walch B glenoids.

Implications of agro-industrial wastes on the durability and erosion characteristics of unfired soil-blocks reinforced with paddy straw fibers: Sustainable earth construction

On Earth, there is an abundance of soil that has been utilized to build homes for millions of people. Manufacturing compacted stabilized adobe blocks requires adequate water added to the appropriate soil type that has been admixed with binders and fibers to attain maximum density. The mixture is then compressed using the appropriate adobe-forming machine. Currently, the major environmental and human health risks worldwide come from industrial and agricultural wastes because of disposal concerns. The production and use of cement and cement blocks bring numerous economic and environmental issues. Utilizing locally available resources and enhancing standard production and testing methods are two feasible options for sustainable growth. Researchers have seen the promise of earthen construction as an alternative building material, and it is becoming more popular in the context of sustainable development. Marble dust (MD) (Industrial waste), sugarcane bagasse ash (SBA), and paddy straw fiber (PSF) (Agricultural wastes) were utilized in this research to manufacture the unfired admixed soil blocks. This study utilizes marble dust composed up to 25%–35%, paddy straw fiber constituted 0.8%–1.2%, and bagasse ash made up 7.5%–12.5% of the soil. The marble-dust-bagasse-ash-soil mix was strongly adherent to PSF, according to SEM investigation. In addition, as is apparent from the image, the number of pores is insignificant. These images support the preceding conclusions regarding this sample’s increased flexural and tensile strength. The primary constituents discovered on the surface of an unfired ad-mixed soil block strengthened with PSF of length 75 mm were silica (Si) and oxygen (O), according to the EDS examination. Aluminum (Al) and magnesium (Mg) were found in trace amounts. The endurance characteristics of the block were determined by conducting different tests on the eighty-one (81) design mixes of the produced unfired ad-mixed adobe blocks, followed by modeling, optimization and microstructural analysis. The results show that the recommended technique improves the durability characteristics of admixed soil blocks without burning better than burnt bricks.

Holistic Approach Uses Electromagnetic Tools, LWD Data To Improve Reservoir Understanding

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 215519, “A Holistic Approach to Data Interpretation Combines the Strengths of Ultradeep Electromagnetic Tools With Shallow Logging-While-Drilling Data To Improve Reservoir Understanding,” by Karol Riofrio, SPE, and Nigel Clegg, Halliburton, and Luke Rawsthorne, Aker BP, et al. The paper has not been peer reviewed. _ During drilling operations, logging-while-drilling (LWD) tools, which have greater resolution than seismic, are deployed to aid in decision-making and optimize well placement. Focusing on the data sources in isolation can lead to successful wells, but placing this data in a geological context allows for more-sophisticated decision-making and leads to greater reservoir understanding. Key to linking the near-wellbore measurements with the geological models derived from seismic interpretation are ultradeep electromagnetic tools. The authors describe an approach in which all available technologies are combined to improve reservoir understanding of different depositional environments. Geological Background Deep marine turbidite deposits are recognized as an important hydrocarbon reservoir type; many recent major hydrocarbon discoveries and field developments worldwide occur in sediments deposited by turbidite currents. Turbidite deposits are characterized by a variety of elements such as large-scale erosive features, channels and channel deposits, overbank deposits, lobes, and channel/ lobe transition zones. Each of these elements contains distinctive characteristics. In this complex setting, better definition of the elements present in the reservoir significantly decreases uncertainty while drilling and can improve the completion design, lengthening well life. Applying different well-acquisition technologies such as ultradeep resistivity (UDAR) inversion and anisotropic inversion and interpretation methodologies such as petrophysical analysis, correlation with spectral decomposition volumes, and 4D seismic can help initially for well placement and subsequently for well-completion design and future development of analogous fields. Methodology The complete paper provides the background, characteristics, and advantages of the following methodologies that the authors used in the study: - 1D UDAR inversion - 3D electromagnetic UDAR inversion - 3D electromagnetic UDAR inversion for anisotropy - Spectral decomposition - 4D Seismic Case Study The strength of combining these tools can be demonstrated in the approach to understanding the results of a single well. In the target well, the main goal was to drain the remaining oil identified by 4D seismic in the target structure. Among the complexities acknowledged predrilling was an undulating oil/water contact (OWC) identified as a result of production from previously drilled wells in the area, the lithological complexity of the reservoir resulting from the turbiditic depositional environment, and the filling history of the field. Identification of these complexities highlighted that the chance of exiting the hydrocarbon-bearing zone was high because of the potential for structural uncertainty and a complex, undulating OWC.

Permafrost degradation and soil erosion as drivers of greenhouse gas emissions from tundra ponds

Climate change poses a serious threat to permafrost integrity, with expected warmer winters and increased precipitation, both raising permafrost temperatures and active layer thickness. Under ice-rich conditions, this can lead to increased thermokarst activity and a consequential transfer of soil organic matter to tundra ponds. Although these ponds are known as hotspots for CO2 and CH4 emissions, the dominant carbon sources for the production of greenhouse gases (GHGs) are still poorly studied, leading to uncertainty about their positive feedback to climate warming. This study investigates the potential for lateral thermo-erosion to cause increased GHG emissions from small and shallow tundra ponds found in Arctic ice-wedge polygonal landscapes. Detailed mapping of fine-scale erosive features revealed their strong impact on pond limnological characteristics. In addition to increasing organic matter inputs, providing carbon to heterotrophic microorganisms responsible for GHG production, thermokarst soil erosion also increases shore instability and water turbidity, limiting the establishment of aquatic vegetation—conditions that greatly increase GHG emissions from these aquatic systems. Ponds with more than 40% of the shoreline affected by lateral erosion experienced significantly higher rates of GHG emissions (∼1200 mmol CO2 m−2 yr−1 and ∼250 mmol CH4 m−2 yr−1) compared to ponds with no active shore erosion (∼30 mmol m−2 yr−1 for both GHG). Although most GHGs emitted as CO2 and CH4 had a modern radiocarbon signature, source apportionment models implied an increased importance of terrestrial carbon being emitted from ponds with erosive shorelines. If primary producers are unable to overcome the limitations associated with permafrost disturbances, this contribution of older carbon stocks may become more significant with rising permafrost temperatures.

Study on the Influence of Urban Water Supply Pipeline Leakage on the Scouring Failure Law of Cohesive Soil Subgrade

Urban water supply pipelines serve as vital lifelines for urban operations. However, the occurrence of underground pipeline leakage, caused by various factors, results in significant water loss and gives rise to safety hazards such as pavement collapse due to the erosive action of leaking water on the overlying soil. To conduct a more comprehensive investigation into the erosion characteristics of the leaking jet on the soil, this study employed a custom-built soil-test system to investigate the erosive effects of leakage from the water supply pipe network on the clay roadbed above. The study considered water flow rate, leakage port size, and leakage angle as influential factors. The experimental results demonstrated that reducing the water flow rate significantly enhances the soil’s erosion resistance. There is a positive correlation between the caliber of pipe leakage, pipe diameter, and the erosion rate of the soil cavity. Under identical conditions, the erosion rate of the specimen increased consistently with an increase in the leakage port angle. The study also investigated and summarized the curve depicting the formation of soil cavities. The aforementioned findings offer valuable insights for the implementation of reinforcement measures using fine-grained cohesive soil backfill in urban water supply pipelines.

An improved method combined modified drag model and modified erosion model based on LES for solid-liquid multiphase flow and erosion with application in a 90° elbow

In various industrial processes, solid-liquid multiphase flows involving continuous carrier and discrete particle phases have erosion challenges. In this work, a modified drag model that considers the influence of turbulence intensity and a modified erosion model that considers the effect of low-angle impact are developed. An improved method combined modified drag model and modified erosion model based on LES is proposed for numerical simulation of solid-liquid multiphase flow and erosion. The commercial software ICEM for grid generation and ANSYS FLUENT for LES are used in the present work. In validation test of velocity distribution of solid-liquid multiphase flow in a vertical pipe, the mean relative error of the liquid phase pulsation velocity is 10.01 % for modified drag model, whereas the mean relative error is 16.11 % for original drag model. In validation test of the maximum erosion depth from a submerged impact test at a tilt angle of 45°, the relative error is 0.23 % for modified erosion model, while the relative error is 13.39 % for original erosion model. Then, the improved method is employed to compute the characteristics of solid-liquid flow and erosion in a 90° elbow. Particles have a significant influence on liquid flow in the shear layer area where the inner arch separation zone interacts with the main flow, and this influence is most pronounced at the position of r* = 0.3 at yd = 0.4D. At this position, particles result in 15.27 % reduction in liquid velocity and 8.75 % increase in turbulence intensity. The mean relative error of the elbow erosion rate by using the improved method is 16.95 %, whereas it is 31.34 % of the reference work. The erosion is affected by impact velocity, angle, and particle number, and the most significant parameter is the particle number in the severe erosion area.

Modification of the swelling behavior of a hydrophilic polymer as an approach to maintaining a constant gel layer thickness

The objective of the present study was to screen some ionic polymers that can modify the swelling and erosion characteristics of a hydrophilic polymer (HPMC) and thereby help provide constant drug release. It was hypothesized that the hydrophilic polymer's swelling rate and erosion of matrices could be modified by adding an ionic polymer, as the two will form a hydrogen bond. Methocel™ K4M (HPMC) was selected as the hydrophilic polymer. NaCMC, Eudragit® S100, and Eudragit® L100 were selected as anionic polymers. Eudragit® RSPO, Eudragit® RLPO and Eudragit® EPO were selected as cationic polymers. Various techniques were used to characterize the rate of swelling, gel layer thickness, and erosion of matrices of HPMC-ionic polymer combinations (3:1 ratio). Fourier-transform infrared spectroscopy was used to study HPMC-ionic polymer interaction. A texture analyzer was used to investigate the change in gel layer thickness and firmness of matrices during dissolution study over time. The stereo microscopic examination provided a structural change in matrices during swelling. Of all the matrices, the HPMC-Eudragit® RSPO combination showed simultaneous swelling and matrix erosion, resulting in constant gel layer thickness (diffusional path length) for 12 h.