91 results on '"erosion prediction"'
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2. Study of loess ecological slope protection optimization measures and prediction of the erosion control effect.
- Author
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Zhang, Xiaochao, Li, Mingli, Yao, Zhongshao, Qin, Liang, and Meng, Minghui
- Abstract
The large-scale management of ditches and implementation of land projects in loess areas have increased the arable land area but have caused considerable engineering issues, resulting in severe soil erosion. In this study, field tests were performed at different time scales, a control group was established, organic material–plant joint restoration technology was proposed as an optimized management measure, and the erosion control mechanism and restoration mode of organic material–plant joint restoration technology were analyzed. Based on the obtained experimental data, a Water Erosion Prediction Project (WEPP)-based hydraulic erosion model was constructed, sensitivity parameters were calibrated, and the soil erosion intensity and corresponding spatial distribution in the watershed of the study area were simulated via the geo-spatial interface for WEPP (GeoWEPP) after organic material–plant joint restoration technology was adopted to predict the effect of optimized management measures. The results showed that among the slopes with different restoration measures, organic material–plant joint restoration technology effectively controlled loess slope erosion, and the average erosion modulus of the organic material–grass and shrub transplantation slope reached only 23.37 t/km
2 , which is a decrease of 97.68% relative to the traditional grass–shrub protection slope. Moreover, the sand content of the joint restoration slope was reduced by 392.41 g/L relative to the bare slope, reaching only 0.29 g/L, and the runoff yield was reduced by 8.88 L/min. The GeoWEPP modeling results revealed that the total runoff yield and average annual erosion modulus of the watershed were lower after joint restoration than during the prerestoration period. Similarly, the total runoff yield of the watershed was 4.6%, the simulated 10-year average annual total sand production reached 2048.3 t, and the average annual erosion modulus was 582.75 t/km2 , which is 52.15% lower than that under untreated conditions. This study provides a new strategy for solving soil erosion problems and restoring the ecology of slopes after managing ditches and implementing land projects. [ABSTRACT FROM AUTHOR] more...- Published
- 2024
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3. An experimental study on the evolution of beach profiles under different beach nourishment methods.
- Author
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Ye Meng, Zhipeng Qu, Xueyan Li, Meixi Zhu, and Bingchen Liang
- Subjects
BEACH erosion ,BEACHES ,BEACH nourishment ,BARRIER islands - Abstract
This document is a compilation of various scientific articles and studies related to coastal engineering, beach nourishment, and shoreline dynamics. The references cover a wide range of topics, including the impacts of nourishment on shoreline response, the use of nature-based solutions for coastal erosion, and the effects of submerged breakwaters. They also discuss the role of waves, sediment transport, and beach profile change in beach nourishment, as well as the effects of nourishment on benthic fauna and the vulnerability of beaches to sea level rise. These references provide valuable information for researchers and decision-makers interested in these subjects. [Extracted from the article] more...
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- 2024
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4. Comprehensive analysis of the effect of structural parameters on erosion wear, structural stress, and deformation of high-pressure double-elbow in shale-gas fracturing
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Siqi Yang, Jianchun Fan, Nan Zhao, Jiakun Yang, Changfeng Xu, Junan Lu, Guanggui Zou, Jianjun Wang, Siwei Dai, and Binchao Zhou
- Subjects
Erosion prediction ,Double-elbow ,Fluid-structure interaction ,Structural parameters ,Numerical simulation ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
In field hydraulic fracturing operation of shale gas development, the high pressure and large displacement liquid-particle two-phase fracturing fluid can be forced to change direction many times through high-pressure double-elbow, and be transported from the outlet pipeline of the fracturing pump to the main pipeline. The high-pressure double-elbow is prone to be affected by erosion wear and Fluid-Structure Interaction (FSI), resulting in perforation and fracture, posing a potential safety threat to field operation. In this study, we conducted the erosion wear experiments on 35CrMo steel used for high-pressure double-elbow in shale-gas fracturing. The erosion rates under different impact angles and flow velocities were obtained, and proposed a novel model of erosion prediction for high-pressure double-elbow. Then the numerical investigation was employed to conduct a comprehensive analysis of erosion wear, structural stress and deformation by the coupling of Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA). The effects of structural parameters such as connection straight pipe length, pipe inner diameter and fluid turning direction were discussed. The results indicate that with the increase of connection straight pipe length, the flow erosion decreases first then varies little, and the deformation gradually increases. Slight erosion wear but large structural stress and deformation in major inner diameter pipe. And the minimum degree of erosion and flow-induced deformation present with the fluid turning direction of double-elbow as 0°. The study can provide references for the design, installation and detection of high-pressure double-elbow and ensure safety in the process of shale gas fracturing. more...
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- 2024
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5. Morphological Model for Erosion Prediction of India’s Largest Braided River Using MIKE 21C Model
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Kuldeep Pareta
- Subjects
river morphology ,hydrodynamics ,erosion prediction ,MIKE 21C ,Brahmaputra River ,Dynamic and structural geology ,QE500-639.5 - Abstract
The Brahmaputra River has a dynamic, highly braided channel pattern with frequent river bar formation, making it morphologically very dynamic, especially during the monsoon season with high discharge and sediment load. To understand how the river changes over time, this study focused on two stretches: Palasbari-Gumi and Dibrugarh. Using 2D morphological models (MIKE-21C), the study aimed to predict erosion patterns, plan protective measures, and assess morphological changes over short-term (1 year), medium-term (3 year), and long-term (5 year) periods. Model runs were conducted to predict design variables across these river reaches, encompassing different hydrological scenarios and development-planning scenarios. The coarse sand fraction yielded mean annual sediment load predictions of 257 Mt/year for the 2021 hydrological year and 314 Mt/year under bankfull discharge conditions in the Palasbari-Gumi reach. In the Dibrugarh reach, the corresponding values were 78 Mt/year and 100 Mt/year. Notably, historical records indicate an annual sediment load of 400 Mt/year in the Brahmaputra River. The model results were compared to measurements from Acoustic Doppler Current Profilers (ADCP), showing good accuracy for flow velocities, flood levels, and sediment loads. Discrepancies in peak model velocities compared to ADCP measurements remain consistently below 9% across the majority of recorded data points. The predicted flood levels for the bankfull discharge condition exhibited an outstanding accuracy, reaching nearly 91% at the Palasbari-Gumi site and a notable 95% at the Dibrugarh site. This study has presented a valuable methodology for enhancing the strategic planning and implementation of river training endeavours, particularly within the dynamic and highly braided channels of rivers such as the Brahmaputra River. The approach leverages predictive models to predict morphological changes over a 2–3 years timeframe, contributing to improved river management. more...
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- 2024
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6. Method for Predicting Service Life of Cage Throttle Valves.
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Yu, Zhang, Zhengwei, Tang, Hanguang, Liu, Jun, Qi, Maotang, Yao, Shi, Wang, Chen, Zhai, and Hao, Peng
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SERVICE life , *MATERIAL erosion , *NATURAL gas , *BRITTLE materials , *VALVES , *PIPELINE transportation , *GRANULAR flow - Abstract
The throttle valve is vital in the oil and gas production stage, designed to decrease natural gas pressure at the wellhead to match transportation pipeline standards. During this process, its flow rate sharply increases, leading to erosion by sand particles discharged from the well's bottom. To predict the cage throttle valve's service life, we established and validated an erosion model for its throttling trim through tests, calculating the erosion wear rate using CFD simulation software. Tests reveal that WC–Co cemented carbide displays typical brittle material traits; its highest erosion wear rate occurs at a 90° impact angle, with a velocity index of 2.4. Study findings indicate the most severe erosion at the smallest orifice of the cage, with the erosion wear rate increasing linearly as particle mass flow rate rises. Consequently, the throttle trim should be inspected and replaced within two years for low mass flow rates of sand particles, or within 3 to 6 months for high mass flow rates. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
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7. Development of erosion equations for removal of organic coating on carbon fiber reinforced polymer surface by plastic abrasive.
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Zhao, Yangyang, Lu, Wenzhuang, Zhu, Yansong, and Zuo, Dunwen
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CARBON fiber-reinforced plastics ,ORGANIC coatings ,EROSION ,MATERIAL erosion ,ABRASIVES - Abstract
Erosion equations were developed to predict the material removal of polyurethane coatings on carbon fiber reinforced plastic (CFRP) surfaces and validated through experimental data. The effects of abrasive properties, process parameters, and organic coating properties (such as fracture toughness and hardness) were considered in the equations. As the erosion angle increased, elastoplastic deformation in the oblique direction and repeated "deformation" in the normal direction were the main reasons for material removal. The ductile erosion behavior was confirmed by experimental data because the maximum erosion rate occurred at an incident angle of 30°. The coefficient and index in the equations were determined by experimental data, and the equations were verified. The developed equations could accurately predict the quantity loss of organic coatings under different particle sizes and particle velocities, and the erosion equations were in good agreement with the experimental data. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
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8. Prediction of Compressor Blade Erosion Experiments in a Cascade Based on Flat Plate Specimen
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Max Lorenz, Markus Klein, Jan Hartmann, Christian Koch, and Stephan Staudacher
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erosion experiment ,dimension analysis ,erosion rate ,erosion prediction ,cascade compressor blade erosion ,Mechanical engineering and machinery ,TJ1-1570 - Abstract
Erosion is an essential deterioration mechanism in compressors of jet engines. Erosion damage predictions require the determination of erosion rates through flat plate experiments. The applicability of the erosion rates is limited to conditions that are comparable to the prevailing boundary conditions of the flat plate experiment. A performed dimensional analysis enables the correct transfer of the flat plate erosion rates to the presented physical calculation model through limits in spatial and time resolution. This efficient approach avoids computationally intensive single-impact computations. The approach features a re-meshing procedure that adheres to the limits derived by the dimensional analysis. The computation approach is capable of describing local geometry changes on cascade compressor blades which are exposed to erosive particles. A linear erosion cascade experiment performed on NASA Rotor 37 provides validation data for the calculated erosion-induced shape change. Arizona Road Dust particles are used to deteriorate Ti-Al6-4V compressor blades. The experiment is performed at an incidence of i = 7°and Ma = 0.76 representing ground idle conditions. The presented parametric study for element size and time step revealed preferable values for the presented computation. Calculations performed with the determined values showed that the erosion prediction is within the measurement tolerance of the experiment and, therefore, high accordance between the computation and the experiment is achieved. To extend the current state of the art, it is demonstrated that the derived discretization is decisive for the correct reproduction of the eroded geometries and fitting parameters are no longer needed. The good agreement between the experimental measurements and the calculated results confirms the correct application of the physical model to the phenomenology of erosion. Thus, the presented physical model offers a novel approach to adapting deterioration mechanisms caused by erosion to any compressor blade geometry. more...
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- 2022
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9. Assessment and Prediction of Soil Erosion and its Impact on the Storage Capacity of Reservoirs in the Bharathapuzha River Basin, India.
- Author
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John, Jisha, Rosamma, Chithra Nelson, and Thampi, Santosh G
- Subjects
SOIL erosion prediction ,WATERSHEDS ,LAND cover ,UNIVERSAL soil loss equation ,SOIL conservation ,SOIL erosion ,SOIL dynamics ,EROSION - Abstract
Soil, one of the non-renewable resources on this planet, is being depleted at an alarming rate due to various anthropogenic activities. The effect of soil erosion could range from on-site ecosystem fragmentation to off-site reservoir storage capacity loss. Though soil erosion is caused by various agents such as wind, water, etc., water erosion is the major type. Heavy rainfall during the monsoons and the relatively thin cover of soil over the bedrock aggravates the damage potential of this form of erosion in the state of Kerala, India. Water-induced soil erosion in the Bharathapuzha river basin in Kerala, which is blessed with cultivable land resources and intensive agricultural activities, has been undertaken for quite long and has started impacting agricultural activities, drinking water supply, and reservoir storage capacity in the basin. In this background, this study was taken up to assess the effects of climate and land use–land cover dynamics on soil erosion in the Bharathapuzha river basin over the last three decades. Soil erosion from the river basin was estimated by the Revised Universal Soil Loss Equation (RUSLE), and these estimates were verified with the observed sediment load in the Bharathapuzha river at the Kumbidi river gauging station. The storage capacity loss of some of the reservoirs located in the river basin, estimated by the Integrated Bathymetric Survey (IBS), was compared with the likely storage capacity loss of these reservoirs estimated based on soil erosion from the catchment areas upstream. Soil loss from the river basin for a future period was predicted using projections of future climate under two Representative Concentration Pathways (RCP 4.5 and RCP 8.5) from four regional climate data experiments and future land use–land cover. Annual soil loss estimation maps for 2020 and 2035 under RCP4.5 and RCP8.5 reveal the urgent necessity to plan and implement soil conservation measures in the erosion hotspots, especially in the Malampuzha, Anamala, and Attapady sub-basins. [ABSTRACT FROM AUTHOR] more...
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- 2022
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10. A model of erosion rate prediction for component with complex geometry based on numerical simulation.
- Author
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Zhang, Yu, Jia, Yun-Fei, Sun, Xin-Wei, Fang, Zhen-Hua, Yan, Jian-Jun, Zhang, Cheng-Cheng, and Zhang, Xian-Cheng
- Subjects
- *
EROSION , *COMPUTER simulation , *AIRFRAMES , *ALUMINUM alloys , *AIRPLANE motors - Abstract
The structural components prone to erosion damage often exhibit irregular and complex shapes. Predicting erosion rates for such irregular geometries is a field that needs more attention, since it can be used to evaluate the performance of the component. This study aims to develop an evaluation method for predicting erosion rates of components with complex geometry. Standard erosion tests were performed on small plates to investigate the effects of different impact angles and particle velocities on the erosion rate of the target material. Based on these test results, the Newton iteration method was employed to determine the parameters of the Tabakoff and Grant erosion model. Moreover, these parameters were used in computational fluid dynamics simulation of components with complex geometries. Besides, a model was developed to convert the erosion rate density into erosion rate in numerical simulation, allowing quantitative comparison of simulation results with experimental data. The calibration of the erosion model parameters was conducted by using 1060 aluminum alloy specimens. The predicted erosion rate changes with impact angle showed consistency good agreement with the testing data. Subsequently, the erosion rate of a simplified similar structure for aircraft engine blade made of 1060 aluminum alloy was predicted and verified. • Determined optimal Tabakoff and Grant erosion model parameters for 1060Al by standard erosion tests. • Quantitative evaluation of erosion rates for components with complex geometry. • A model for conversion of erosion rate density to erosion rate was proposed. • Effectively predicted erosion rates for a simplified structure of aircraft engine blade. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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11. Analysis on the influence of turbulence model on elbow erosion calculation
- Author
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Liu Qi, Mao Shaohua, Liu Sheng, Hu Yangyang, Jiang Wei, and Long Xinping
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elbow flow ,turbulence model ,erosion prediction ,Computational Fluid Dynamics(CFD) ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 - Abstract
[Objectives] The elbow is a common component of ship piping system. Efforts have been made in order to predict the elbow erosion accurately.[Methods] In this paper,the numerical simulation is conducted to calculate and analyze the flow field inside the pipe. From the two aspects,i.e. the influence of the turbulence model on the prediction of the flow field in the elbow and the influence of turbulence model on elbow erosion calculation,intensive research into the method to predict the erosion of elbow by solid and liquid flows.[Results] The results show that the SST k-ω turbulence model,together with the Oka erosion model,can accurately predict the flow field distribution in the elbow. Turbulence model brings a significant impact on the abrasion calculation,where it affects the calculated value of final erosion and also makes a great difference in the distribution of predicted relative erosion.[Conclusions] The obtained results can provide guidance for future pipe erosion prediction. more...
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- 2019
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12. Impact of land-use change on soil erosion in the Coonoor Watershed, Nilgiris Mountain Range, Tamil Nadu, India.
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Saravanan, Subbarayan, Jennifer, Jesudasan Jacinth, Singh, Leelambar, Thiyagarajan, Saranya, and Sankaralingam, Sivaranjani
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The conversion of native forest to the tea plantation and cropland has intensified throughout the Coonoor watershed of the Nilgiris region over the past few decades. The current study investigates the severity of land cover changes including deforestation activities in the Coonoor watershed region as a result of urbanization, along with the establishment of recreational parks, resorts and tea plantations. In order to analyse the changes, a widely used soil erosion model say Revised Universal Soil Loss Equation (RUSLE) is opted to estimate the average soil loss. Therefore, this work marks the impact of land-use changes on land degradation and the consequent vital natural phenomenon like soil erosion. The change detection was carried out for over 14 years period from 2005 to 2018. Landsat images of corresponding years were classified using the supervised classification technique. The C-factor (cover and management factor) for the corresponding periods were also identified. Conversion of forest land into tea plantations, wastelands and settlements significantly decrease the soil organic matter (SOM) and hydraulic conductivity (HC) of the soil, which leads to a difference in the K-factor (soil erodibility factor) throughout the study period, whereas the R-factor (rainfall and runoff factor) and LS-factor (length-slope factor) were considered to be constant throughout the period. Results indicate the annual soil loss during the period from 2000 to 2018 on each land use/cover classes. viz., tea plantations, 223.26 km
2 ; settlement, 163.35 km2 ; open forest, 799.02 km2 ; dense forest, 1158.48 km2 ; and barren land, 27.18 km2 . The total sediment yield in the study area was found to have oddly increased due to the land use/cover changes. The significant rise of soil erosion was found evitable in the deforested region which was converted to infrastructure and wasteland. [ABSTRACT FROM AUTHOR] more...- Published
- 2021
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13. 三峡大坝—葛洲坝河段水沙变化及冲淤特性.
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史常乐, 牛兰花, 赵国龙, and 杜林霞
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HYDRAULICS , *PEAK load , *EROSION , *SEDIMENTS , *RIVER channels , *DAMS , *MEASUREMENT of runoff ,SAN Xia Dam (China) - Abstract
A correct understanding of the variation pattern of water and sediment conditions as well as erosion and deposition characteristics in the reach between Three Gorges Dam and Gezhou Dam is essential for studying the many engineering problems in the reach. In this study, abundant water-sediment topographic data were analyzed, and the application of the theory of sediment incipient motion in erosion prediction was discussed. Owing to reservoir construction in the upper reaches of the Yangtze River and the successive operation of the two major hubs, the annual runoff in the reach was slightly reduced, the monthly average runoff was redistributed by “peak load shifting?” the annual sediment discharge declined considerably, and the water-sediment relationship in the reach was significantly changed. The cumulative erosion and deposition quantity in the reach was under short- and long-term control by the extreme hydrological conditions and scheduling of the hubs. In terms of time, there were apparent phased characteristics, in terms of space, some sub-reaches were in an active state. The bed sediment was refined and coarsened successively with the operation of the hub. The incipient critical condition curve was drawn based on Sha's incipient velocity equation, and the estimation of the maximum particle size of movable bed sediment or critical water flow of the cross-section provided a reference for predicting the possibility of riverbed erosion. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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14. An integrated model of predicting sand erosion in elbows for multiphase flows.
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Kang, Rong and Liu, Haixiao
- Subjects
- *
MULTIPHASE flow , *EROSION , *FLOW coefficient , *GAS flow , *SAND , *ELBOW - Abstract
Sand erosion is a serious problem to be solved in the oil and gas industry. During the transportation of oil and gas, different multiphase flow patterns may occur due to variations of factors, such as the conveying speed, fluid property and pipe geometry. The present work aims at developing a novel framework to predict sand erosion in elbows for multiphase flows. Firstly, the effects of flow patterns on sand erosion are analyzed. Based on these analyses, the erosion model for each specific flow pattern is established. Combining with the basic penetration ratio in gas flow and erosion coefficients, the erosion models of different flow patterns can be unified as an integrated model. Then, the accuracy of the integrated model is examined by 108 experimental cases. After the experimental validation, an optimal coefficient is proposed to further optimize the integrated model. A comparison between the optimized integrated model and the non-optimized integrated model is performed. The results demonstrate that the optimized integrated model performs well in improving the accuracy. Finally, the integrated model is compared with other existing erosion models. According to the comparative study, the non-optimized integrated model already owns the similar accuracy compared with existing erosion models, while the optimized integrated model performs best in accuracy and efficiency. Unlabelled Image • An integrated model is developed to predict sand erosion in elbows for multiphase flows. • Erosion coefficients are proposed to simplify models of different flow patterns. • The optimal coefficient shows advantages in improving the accuracy of prediction. • Maximum penetration ratio can be easily predicted with high accuracy. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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15. Soil detachment by overland flow on steep cropland in the subtropical region of China.
- Author
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Ma, Qianhong, Zhang, Keli, Cao, Zihao, Wei, Mengyao, and Yang, Zhicheng
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SOILS ,SOLIFLUCTION ,SOIL erosion ,STREAM function ,SHEARING force - Abstract
Accurate prediction of soil detachment capacity is fundamental to establish process‐based erosion models and improve soil loss assessment. Few studies were conducted to reveal the mechanism of detachment process for yellow soil on steep cropland in the subtropical region of China using field experiments. This study was performed to determine soil detachment characteristics and explore the relationships between soil detachment capacity (Dc) and flow rate, slope gradient, mean velocity, shear stress, stream power and unit stream power. Field experiments were conducted on intact soil with flow rates ranging from 0.2 × 10−3 to 0.5 × 10−3 m−3 s−1 and slope gradients varying from 8.8 to 42.4%. The results showed the following. (a) Dc of yellow soil was smaller than other soils because of its high clay content. (b) Dc was more susceptible to flow than to slope gradient. Power functions were derived to depict the relationship between Dc and the flow rate and slope gradient (R2 = 0.91). (c) Dc was better simulated by power functions of the stream power (R2 = 0.83) than functions of the shear stress or the unit stream power. (d) Considering its accuracy, simplicity and accessibility, the power function based on flow rate and slope gradient is recommended to predict Dc of yellow soil in the field. The results of this study provide useful support for revealing soil detachment mechanism and developing process‐based soil erosion models for the subtropical region of China. [ABSTRACT FROM AUTHOR] more...
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- 2020
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16. Assessment of soil erosion risk and its response to climate change in the mid-Yarlung Tsangpo River region.
- Author
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Wang, Li, Zhang, Fan, Fu, Suhua, Shi, Xiaonan, Chen, Yao, Jagirani, Muhammad Dodo, and Zeng, Chen
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SOIL erosion ,UNIVERSAL soil loss equation ,CLIMATE change ,SNOWMELT ,VEGETATION dynamics - Abstract
Soil erosion is sensitive to climate change, especially in high mountain areas. The Tibetan Plateau has experienced dramatic land surface environment changes under the impact of climate change during the last decades. In this study, we focused on the mid-Yarlung Tsangpo River (MYZ River) located in the southern part of the Tibetan Plateau. The revised universal soil loss equation (RUSLE) was applied to assess soil erosion risk. To increase its applicability to high mountain areas with longer periods of snowfall, snowmelt runoff erosivity was considered in addition to rainfall erosivity. Results revealed that soil erosion of the MYZ River region was of a moderate grade with an average soil erosion rate of 29.1 t ha
−1 year−1 and most serious erosion in wet and cold years. Soil erosion rate in the MYZ River region showed a decreasing trend of − 1.14% year−1 due to the precipitation, temperature, and vegetation changes from 2001 to 2015, with decreasing precipitation being the most important factor. Increasing precipitation and temperature would lead to increasing soil erosion risk in ~ 2050 based on the Coupled Model Intercomparison Project (CMIP5) and RUSLE models. It is clear that soil erosion in high mountain areas greatly depends on climate state and attentions should be paid to address soil erosion problem in the future. [ABSTRACT FROM AUTHOR] more...- Published
- 2020
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17. The uncertain future of mountaintop-removal-mined landscapes 2: Modeling the influence of topography and vegetation.
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Bower, Samuel J., Shobe, Charles M., Maxwell, Aaron E., and Campforts, Benjamin
- Subjects
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RENEWABLE energy transition (Government policy) , *TOPOGRAPHY , *VALLEYS , *LANDSCAPES , *STRIP mining - Abstract
Erosion following human disturbance threatens ecosystem health and inhibits effective land use. Mountaintop removal/valley fill (MTR/VF) mined landscapes of the Appalachian Coalfields region, USA, provide a unique opportunity to quantify the geomorphic trajectory of disturbed lands. Here we assess how MTR/VF-induced changes to topography and vegetation influence spatiotemporal erosion patterns in five mined watersheds. We use landscape evolution models starting from pre- and post-MTR/VF topographic data to isolate the influence of mining-induced topographic change. We then constrain ranges of erodibility from incision depths of gully features on mine margins, and use those estimates to model the influence of vegetation recovery trends on erosion. Topographic alterations alone reduce total sediment export from mined catchments. Model runs that incorporate the disturbance and recovery of vegetation in mined watersheds show that complete vegetation recovery keeps millennial sediment export from mined catchments within the range of unmined catchments. If vegetation recovery is anything less than complete, vegetation disturbance drives greater total sediment export from mined catchments than unmined catchments. Full vegetation recovery causes sediment fluxes to decline over millennia beyond the recovery period, while watersheds without full recovery experience fluxes that increase over the same time period. Spatiotemporal erosion trends depend on 1) the extent of vegetation recovery and 2) the extent to which MTR/VF creates slope–area disequilibrium. Valley fills and mine scarps experience erosion rates several times higher than those found in the unmined landscapes. Rapid erosion of mined areas drives deposition in colluvial hollows, headwater stream valleys, and below scarps. Our experiments suggest that reclamation focused on maximizing vegetation recovery and reducing hotspots of slope–area disequilibrium would reduce MTR's influence on Appalachian watersheds both during and long after the vegetation recovery period. Insights from MTR/VF-influenced landscapes can inform mined land management as the renewable energy transition drives increased surface mining. [Display omitted] • We model 10,000 years of erosion beginning from both pre- and post-mining topography. • Mining-driven topographic changes alone reduce total erosion due to ridge flattening. • Incomplete vegetation recovery increases erosion in mined over unmined basins. • Erosion is focused in valley fills, deposition in low-order valleys and below scarps. • Vegetation recovery sets decadal sediment pulses and millennial landscape trajectory. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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18. The uncertain future of mountaintop-removal-mined landscapes 1: How mining changes erosion processes and variables.
- Author
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Shobe, Charles M., Bower, Samuel J., Maxwell, Aaron E., Glade, Rachel C., and Samassi, Nacere M.
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EROSION , *SURFACE of the earth , *COAL mining , *ENVIRONMENTAL degradation , *LANDSCAPES , *UNSTEADY flow , *CULTURAL landscapes , *STRIP mining - Abstract
Surface mining may be humanity's most tangible impact on Earth's surface and will become more prevalent as the energy transition progresses. Prediction of post-mining landscape change can help mitigate environmental damage, but requires understanding how mining changes geomorphic processes and variables. Here we investigate surface mining's complex influence on surface processes in a case study of mountaintop removal/valley fill (MTR/VF) coal mining in the Appalachian Coalfields, USA. The future of MTR/VF landscapes is unclear because mining's effects on geomorphic processes are poorly understood. We use geospatial analysis—leveraging the existence of pre- and post-MTR/VF elevation models—and synthesis of literature to ask how MTR/VF alters topography, hydrology, and land-surface erodibility and how these changes could be incorporated into numerical models of post-MTR/VF landscape evolution. MTR/VF reduces slope and area–slope product, and rearranges drainage divides. Creation of closed depressions alters flow routing and casts doubt on the utility of models that assume steady flow. MTR/VF creates two contrasting hydrologic domains, one in which overland flow is generated efficiently due to a lack of infiltration capacity, and one in which waste rock deposits act as extensive subsurface reservoirs. This dichotomy creates localized hotspots of overland flow and erosion. Loss of forest cover probably reduces cohesion in near-surface soils for at least the timescale of vegetation recovery, while waste rock fills and minesoils also likely experience reduced erosion resistance. Our analysis suggests three necessary ingredients for numerical modeling of post-MTR/VF landscape change: 1) accurate routing and accumulation of unsteady overland flow and accompanying sediment across low-gradient, depression-rich, engineered landscapes, 2) separation of the landscape into cut, filled, and unmined regions, and 3) incorporation of vegetation recovery trajectories. Improved modeling of post-mining landscape evolution will mitigate environmental degradation from past mining and reduce the impacts of future mining that supports the energy transition. [Display omitted] • Mountaintop removal mining flattens topography and moves drainage divides. • Cut and filled domains generate different quantities of erosive runoff. • Creation of many closed depressions reduces applicability of common models. • Vegetation loss and material property changes increase erodibility. • Our work reveals the necessary elements for models of post-mining landscape change. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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19. Prediction of Erosion-Prone Areas in the Catchments of Big Lowland Rivers: Implementation of Maximum Entropy Modelling—Using the Example of the Lower Vistula River (Poland)
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Marta Brzezińska, Dawid Szatten, and Zygmunt Babiński
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erosion prediction ,maximum entropy model ,USLE model ,Vistula River ,Science - Abstract
It is common knowledge that erosion depends on environmental factors modified by human activity. Erosion within a catchment area can be defined by local lithological, morphometric, hydrological features, etc., and land cover, with spatial distribution described by means of remote sensing tools. The study relied on spatial data for the catchment of the Lower Vistula—the biggest river in Poland. GIS (SAGA, QGIS) tools were used to designate the spatial distribution of independent environmental variables that determined the process of erosion according to land cover types within the Lower Vistula catchment (Corine Land Cover). In addition, soil loss in the catchment area was calculated using the USLE model (Universal Soil Loss Equation). The spatial data was used to determine the predictive power of variables for the process of erosion by applying the maximum entropy model (MaxEnt) commonly used in fields of science unrelated to fluvial hydrology. The results of the study pointed directly to environmental features strongly connected with the process of erosion, identifying areas susceptible to intensified erosion, and in addition positively verified by USLE. This testifies to the correct selection of the proposed method, which is a strong point of the presented study. The proposed interdisciplinary approach to predict erosion within the catchment area (MaxEnt), widely supported by GIS tools, will allow the identification of environmental pressures to support the decision-making process in erosion-prone areas. more...
- Published
- 2021
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20. A unified explicit correlation of predicting the sand erosion in elbows for gas and annular flows based on probability analysis.
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Kang, Rong and Liu, Haixiao
- Subjects
- *
ANNULAR flow , *MATERIAL erosion , *GAS flow , *ELBOW , *GROUNDWATER flow , *FLOW coefficient , *EROSION - Abstract
The elbows are susceptible to the sand erosion during the transportation of oil and gas, especially for gas and annular flows. The objective of present work is to provide a simple and efficient method for predicting the sand erosion in elbows for both gas and annular flows. First, mechanistic analyses of the sand erosion in annular flow are conducted, and an erosion reduction coefficient is deduced to unify the erosion calculation in gas and annular flows. The erosion reduction coefficient is verified by a series of simulations with varying parameters, such as the superficial gas velocity, superficial liquid velocity, radius of curvature, pipe diameter, particle diameter and hardness of pipe wall. Then, the simulation results are employed to investigate the effects of second collision on the total erosion. Based on the investigation, two enhancement coefficients are proposed to estimate the contribution of second collision to the maximum penetration ratio and the most serious erosion position. Finally, by combining the above coefficients and the probability erosion models, a unified explicit correlation is derived for predicting the sand erosion in elbows and examined by the experimental data in gas and annular flows. The comparative study indicates that the new correlation performs well not only in simplifying the probability erosion models but also in predicting the maximum penetration ratio and the most serious erosion position. • A unified explicit correlation is proposed to predict sand erosion in elbows for gas and annular flows. • An erosion reduction coefficient in annular flow is deduced through mechanistic analyses. • Penetration enhancement coefficients are proposed to reflect the contribution of second collision to total erosion. • The correlation unifies and simplifies the probability models for gas and annular flows. • Maximum penetration ratio and most serious erosion position can be easily calculated without reducing accuracy. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
- Full Text
- View/download PDF
21. Predicting erosion in a non-Newtonian shear-thinning jet flow with validated CFD models from PIV and PTV measurements.
- Author
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Wang, Zhiguo, Zhang, Jun, Shirazi, Siamack A., and Dou, Yihua
- Subjects
- *
NON-Newtonian flow (Fluid dynamics) , *JETS (Fluid dynamics) , *COMPUTATIONAL fluid dynamics , *JET impingement , *MATERIAL erosion , *NON-Newtonian fluids - Abstract
In oil and gas industry, an increase in production is often achieved by injecting fracturing fluids with particles/proppants into rocks and reservoirs. There are various fracking fluids that oil and gas companies use, and some of these fracturing fluids demonstrate non-Newtonian flow behavior. In this paper, sand erosion behavior in shear-thinning carboxymethyl cellulose (CMC) solution is investigated with a jet impingement facility. Particularly, near wall flow speeds and particle impinging speeds are investigated in shear-thinning CMC fluids by Particle Image Velocimetery (PIV) and Particle Tracing Velocimetery (PTV) techniques. Computational Fluid Dynamics (CFD) are also used to predict the near wall particle impact information. The results indicate that different turbulence models resolve different near wall flow and particle impact characteristics. User Defined Functions (UDF) are developed and used to implement erosion ratio equations and simulate solid particle erosion behavior in the non-Newtonian fluid. The predictions are compared with experimental results. The results of this study can help improving erosion prediction in the hydraulic fracturing process utilizing CFD. • Erosion with shear-thinning CMC solution and sand particles are investigated with a jet impingement facility. • Cross constitutive model is implemented with CFD and is validated by PIV measurement. • Different turbulence models were conducted by predicting particle impact speeds and validated by PTV measurement. • Turbulence models are optimized to simulate erosion in non-Newtonian fluid and are comparison with erosion data. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
- Full Text
- View/download PDF
22. A probability model of predicting the sand erosion in elbows for annular flow.
- Author
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Kang, Rong and Liu, Haixiao
- Subjects
- *
ANNULAR flow , *EROSION , *PROBABILITY theory , *LIQUID films , *COMPUTATIONAL fluid dynamics - Abstract
Abstract Annular flow is a common flow pattern in oil and gas pipelines for its stability and efficiency. During the oil and gas production, sand particles are inevitably carried by annular flow to continuously impact on elbows, and thus make the sand erosion in elbows a notable problem. In the present work, both the first and second collisions are taken into account in the collision probability analysis. The decay effects of liquid film on particles are considered in calculating the impact velocities of particles, and the particle impact information is introduced into erosion correlations to estimate the erosion ratio. By combining the collision probability models and the erosion correlations, a novel probability model for annular flow is developed to predict the sand erosion in elbows. Numerous experiments are employed to examine the accuracy of the present model, and the applicability and efficiency of the probability model are demonstrated by comparing with other erosion models. Finally, the effects of first and second collisions on the formation of erosion profiles, as well as the relations between the erosion profile and the superficial gas velocity, superficial liquid velocity and curvature of elbow, are investigated in detail to acquire more knowledge of the sand erosion in elbows under annular flow conditions. Highlights • A probability model for annular flow is developed to predict the sand erosion in elbows. • Decay effects of liquid film on particle velocities are firstly introduced in theoretical analysis. • The erosion caused by second collision in annular flow is considered in analysis. • Maximum penetration rates and entire erosion profiles can be directly calculated. • The model shows advantages in both applicability and accuracy of prediction. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
- Full Text
- View/download PDF
23. Experimental and numerical study of erosion in a non-Newtonian hydraulic fracturing fluid.
- Author
-
Wang, Zhiguo, Zhang, Jun, Shirazi, Siamack A., and Dou, Yihua
- Subjects
- *
NON-Newtonian fluids , *HYDRAULIC fracturing , *COMPUTATIONAL fluid dynamics , *DISCRETE systems , *TURBULENCE - Abstract
Abstract Erosion in hydraulic fracturing fluid is investigated utilizing Computational Fluid Dynamics (CFD) and with comparison to new experimental data for sand in shear thinning non-Newtonian fluids. A grid optimized CFD-based erosion prediction procedure is applied utilizing Dense Discrete Phase Model (DDPM) and one-way coupling model. The effect of different turbulence models on flow modeling, sand particle transport and impact characteristics are also examined. Constant viscosity fluid and power law constitutive equations are implemented and their capability in predicting erosion is examined by comparison to experimental data gathered in this investigation. This investigation has shown that significant error can arise from utilizing constant viscosity model to predict erosion resulting from particles entrained in non-Newtonian fluids. Thus, this investigation has resulted in selecting the best CFD approach and model combination for predicting erosion in this hydraulic fracturing non-Newtonian fluid. Highlights • Shear-thinning fluid rheology is implemented and flow field is simulated. • Dense Discrete Phase Model is applied and prediction results have been improved. • Near wall flow information and particle impact characteristics are investigated in detail to explain prediction results. • The best model combination to simulate erosion in non-Newtonian fluid is derived by comparison with erosion data. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
- Full Text
- View/download PDF
24. Erosivity and seasonal rainfall for Pelotas-RS, Brazil with the RainfallErosivityFactor package and Modified Fournier Index.
- Author
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Nunes, Maria Cândida Moitinho, Cardoso, Dione Pereira, Melo, Tainara Vaz, Dorneles, Viviane Rodrigues, Knapp, Ana Paula, and Cecconello, Samanta Tolentino
- Subjects
- *
SOIL erosion prediction , *SEASONS , *RAINFALL , *AUTUMN , *EROSION - Abstract
One of the main factors affecting water erosion is rainfall erosivity. Knowledge of this factor can contribute to the prediction of soil losses and to the identification of the most suitable periods for agricultural cultivation operations. The use of software, based on current calculation tools, can contribute to the quick and accurate analysis of long series of rainfall data. The objective of this work is to determine the rainfall volume and rainfall erosivity (R), in different seasons of the year, through the correlation between the EI30 index, the rainfall coefficient (Rc) and the Fournier Index modified (MFI), for rainfall data from Pelotas-RS-Brazil. Rainfall data was used with an interval of 10 min, from 1993 to 2015, evaluated with the RainfallErosivityFactor package of the R-Project software. In the package, the R-factor is obtained by averaging the monthly EI30 values from the data series. Data was evaluated on a monthly, annual and seasonal scale. It was found that the average annual rainfall is 1369.46 mm, with February being the month with the highest rainfall. The series of annual precipitation data did not show a significant trend according to the Mann-Kendall test and the average annual erosivity is 8166.8 MJ mm h−1 ha−1 yr−1. Erosivity in summer is significantly higher than in winter, with the summer-autumn period accounting for 64.4% and winter represented only 17% of annual erosivity. There is a strong positive correlation between the erosivity and the rainfall coefficient, for monthly average data. Erosivity and MFI showed a very strong significant correlation for summer and autumn. The rainfall coefficient tended to show lower values in March and higher values in February. The results obtained are important to identify the periods of most critical erosivity, in which management systems must prioritize surface coverage and minimum soil disturbance. [Display omitted] • The month with the highest average monthly rainfall is February (153.0 mm). • November to February have the highest average erosivity. • The average annual erosivity for Pelotas-RS (1993–2015) is 8166.8 MJ mm h−1 ha−1 year−1. • The highest volumes of rain and the highest erosivity occur in the summer. • EI30 and MFI showed a very strong correlation for the summer/autumn period. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
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25. Analysis of Soil Erosion Hazardous Level In Jatipurno Sub-District Of Wonogiri District
- Author
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Apriani Widiatiningsih, Mujiyo Mujiyo, and Suntoro Suntoro
- Subjects
erosion prediction ,soil conservation planning ,USLE ,Environmental sciences ,GE1-350 - Abstract
The aim of this research was to analyze erosion hazardous level (TBE) and predict the actual erosion (A) at Jatipurno Sub-District and planning of soil conservation when the actual erosion is more than the threshold at Jatipurno District. The USLE (Universal Soil Loss Equation) was used to predict actual erosion and erosion hazardous level then planning of soil conservation. The result showed that actual erosion level was varied from very light to heavy. The very light erosion, in range 0,2 ton/ha/yr to 7,8 ton/ha/yr the areas is about 1.879,19 ha (43,5%). The light erosion is 51,96 ton/ha/yr the areas is about 788,40 ha (18,3%). The moderate erosion is 92,83 ton/ha/yr the areas is about 694.95 ha (16,1%). The heavy erosion in range 209,84 ton/ha/yr to 377,21 ton/ha/yr the areas is about 952,80 ha (22,1%). Erosion hazardous level was varied from very light to very heavy. The very light erosion hazardous level covered areas of 1.034,77 ha (23,98%), the light erosion hazardous level covered areas 1.443 ha (33,44%), the heavy erosion hazardous level covered areas 1.204 ha (27,91%), the very heavy erosion hazardous level covered areas 632,88 ha (14,67%). Actual erosion dominated by very light level and TBE by the light level. Soil conservation planning is carried out by vegetative and mechanical conservation measures, such as planting variations of cover crops and terraces built in accordance with slope land and soil depths, land management according to local environmental and cultural preservation regulations and cooperation of all parties in environmental management can be done to prevent and minimize erosion. more...
- Published
- 2018
- Full Text
- View/download PDF
26. Numerical prediction of cavitation erosion on a ship propeller in model- and full-scale.
- Author
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Peters, Andreas, Lantermann, Udo, and el Moctar, Ould
- Subjects
- *
CAVITATION erosion , *SPALLING wear , *STRUCTURAL dynamics , *BOUNDARY element methods , *LARGE eddy simulation models , *METAL cutting - Abstract
The cavitating flow around a ship propeller was simulated with an implicit RANS based flow solver using the Volume of Fluid (VoF) method to model the interface between the two phases. The sliding interface method was applied to simulate the rotation of the propeller, comprising a rotor and a stator region. Erosion was predicted with a numerical model based on the microjet hypothesis, using the information from the flow solution. Simulations of a propeller under non-cavitating and cavitating conditions were compared to experimental measurements, thereby demonstrating the ability of the presented numerical method to qualitatively predict cavitation erosion for a ship propeller. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
- View/download PDF
27. Uncertainty quantification in erosion predictions using data mining methods.
- Author
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Dai, Wei, Cremaschi, Selen, Subramani, Hariprasad J., and Gao, Haijing
- Subjects
- *
RESIDUAL stresses , *COMPRESSIVE strength , *WEAR resistance , *MECHANICAL wear , *STRENGTH of materials , *DATA mining , *REGRESSION analysis - Abstract
The transport of solids in multiphase flows is common practice in energy industries due to the unavoidable extraction of solids from oil and gas bearing reservoirs. The persistent collision of solids to the pipeline can lead to erosion, i.e., the removal of internal surface of the pipeline. Reliable estimates of erosion rates are essential for designing and safely operating pipelines that transport solids. Prediction of erosion rates in multiphase flow is a complex problem due to the lack of accurate models for predicting particle movements in the flow and their impact velocities to the wall. The erosion-rate calculations also depend on the accuracy of the flow regime predictions in the pipeline. The comparisons of existing model predictions to experimental data revealed that the predictions might differ by several orders of magnitude for some operating conditions. The goal of this paper is to introduce a computational framework that estimates the model-prediction uncertainty of erosion-rate models. The inputs are a model predicting erosion rates and a database containing erosion-rate measurements at various operating conditions. The framework utilizes a non-parametric regression analysis, Gaussian Process Modeling (GPM), for estimating the model-prediction uncertainty. We compare two approaches for clustering the data prior to training GPMs: (1) a flow regime based clustering, and (2) a new clustering approach introduced in this paper. The results reveal that the new data clustering approach significantly shrinks the confidence intervals of the uncertainty estimates. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
- View/download PDF
28. Numerical investigation of the maximum erosion zone in elbows for liquid-particle flow.
- Author
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Pei, Jie, Lui, Aihua, Zhang, Qiong, Xiong, Ting, Jiang, Pan, and Wei, Wei
- Subjects
- *
LIQUIDS , *FLUID flow , *PIPE , *MANUFACTURING processes , *COMPUTATIONAL fluid dynamics , *PIPELINE transportation - Abstract
Erosion caused by particles transported in pipes is a major concern in industrial processes. To describe the erosion behavior in elbows, the flow field, particle trajectories, and relationship between the maximum erosion zone and influencing factors were investigated by using computational fluid dynamics (CFD). The accuracy of the presented method was verified by experimental data available in the literature. Good agreement between the predictions and experimental data was observed. Furthermore, the particle diameter, pipe geometry parameters, and operating conditions in pipeline transportation were analyzed to determine the maximum erosion zone. The results show that (1) the Stokes number for particle motion in the elbow has a certain effect as the particles move with the eddy but has no decisive influence on the location of the maximum erosion zone; (2) the erosion zone is directly related to the particle diameter; and (3) increasing the radius of curvature will change the flow field in the pipe and, in turn, the location of the maximum erosion zone. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
- View/download PDF
29. A correlation for sand erosion prediction in annular flow considering the effect of liquid dynamic viscosity.
- Author
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Liu, Haixiao, Yang, Weixuan, and Kang, Rong
- Subjects
- *
PIPELINES , *EROSION , *VISCOSITY , *ANNULAR flow , *ACCURACY - Abstract
Sand erosion is a common problem in oil and gas industry, which may lead to unpredictable failure and economic loss of pipeline systems. Due to the relatively stable state, annular flow is the predominant flow pattern and can simultaneously transport two kinds of materials (such as liquid and gas), which can reduce expenses for oil and gas production. In the present work, an accurate combination of the correlations of entrainment fraction and liquid film thickness is introduced into a modified numerical model, and is validated by experimental data. A series of numerical simulations are designed and performed to investigate the coupling effects of different parameters on erosion, such as the liquid dynamic viscosity, pipe diameter, superficial gas velocity, radius of curvature, superficial liquid velocity and particle size. Based on the knowledge gained from numerical analysis, the dimensionless π groups are proposed as well as a correlation for predicting sand erosion in annular flow, which takes the effect of liquid dynamic viscosity into account. By comparing with the experimental data and other existing correlations, the proposed correlation is confirmed as an effective and concise method, and shows good accuracy in erosion prediction. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
- View/download PDF
30. An empirical approach to predict droplet impact erosion in low-pressure stages of steam turbines.
- Author
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Ahmad, M., Schatz, M., and Casey, M.V.
- Subjects
- *
STEAM-turbine blades , *YOUNG'S modulus , *HARDNESS , *PREDICTION models , *EROSION - Abstract
At the Institute of Thermal Turbomachinery and Machinery Laboratory (ITSM) Stuttgart, the droplet impact erosion phenomenon has been simulated with the help of an erosion test rig. The experiments confirm that the erosion resistance of steam turbine blade materials can be associated with different mechanical properties of materials. Different combinations of material properties, like hardness, yield strength, Young's modulus and resilience, are analysed and their role in the formation of material erosion resistance is investigated. These material properties are, later on, used to predict the erosion behaviour of blade materials in a given erosive environment. In the end, an empirical erosion prediction model is presented and described. With the help of this erosion model, the rig-specific erosion resistance of a candidate blade material can be predicted if its material properties are known. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
- View/download PDF
31. Experimental Study on Particle Erosion Failure of Abrupt Pipe Contraction in Hydraulic Fracturing.
- Author
-
Cheng, Jiarui, Dou, Yihua, Zhang, Jiding, Zhang, Ningsheng, Li, Zhen, and Wang, Zhiguo
- Subjects
- *
FAILURE analysis , *EROSION , *PIPELINES , *HYDRAULIC fracturing , *FLOW velocity - Abstract
Erosion damage is one of the main factors leading to failure of pipeline in oil field, especially for sudden contraction section under solid-liquid two-phase flow in hydraulic fracturing. In this article, a laboratory experiment was carried out to analyze the effects of pipe flow velocity, particle concentration and pipe inner diameter ratio on particle erosion of the reducing wall in high-viscosity liquid. The results show that the erosion rate and erosion distribution are different not only in radial direction but also in circumferential direction of the sample. The upper part of sample always has a minimum erosion rate and erosion area. Besides, the erosion rate of reducing wall is most affected by fluid flow velocity, and the erosion area is most sensitive to the change in the diameter ratio. Meanwhile, the erosion rate of reducing wall in cross-linked fracturing fluid is mainly determined by the fluid flowing state due to the high viscosity of the liquid. In general, the increase in flow velocity and diameter ratio not only causes the expansion of erosion-affected flow region in sudden contraction section, but also leads to more particles impact the wall. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
- View/download PDF
32. RUSLE erodibility of heavy‐textured soils as affected by soil type, erosional degradation, and rainfall intensity: A field simulation.
- Author
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Wu, Xinliang, Wei, Yujie, Wang, Junguang, Cai, Chongfa, Deng, Yusong, and Xia, Jinwen
- Subjects
SEDIMENTATION & deposition ,TROPICAL climate ,LAND degradation ,SOIL erosion ,SOIL corrosion - Abstract
Abstract: Soil erosion is a serious problem world‐wide for the environment or humankind, exacerbating land degradation. However, little systematic knowledge is available about the erodibility of various types of soils at different erosional degradation levels, especially at the field scale. In this research, the spatiotemporal variations of the erodibility for 5 soil types (calcic luvisol, ferric luvisol, plinthic alisol, plinthic acrisol, and acric ferralsol) from temperate to tropical climate were investigated with field rainfall simulation experiments on prewetted bare fallow heavy‐textured soils (silty clay loam, silty clay, and clay) derived separately from loess deposits, quaternary red clays, and basalt. The experiments were performed in 3 erosion classes (noneroded, moderately eroded, and very severely eroded) and at 2 rainfall intensities (45 and 90 mm hr
−1 ). Soil erodibility was represented by the K factor of the Revised Universal Soil Loss Equation. Soil erodibility was the lowest for the ferralsols among all the soil types and was significantly lower in the very severe than in the no or moderate erosion classes. Soil erodibility tended to be larger at the high than at the low rainfall intensity (p < .05) except for the very severely eroded luvisols, and their difference between rainfall intensities in the erodibility varied with rainfall duration. Soil erodibility could be well predicted by the combination of illite, dry aggregate stability, and amorphous aluminium oxides (adjusted R2 = .51, p < .001), and its temporal variations were significantly related with particle density, 1.4‐nm intergrade mineral, and capillary porosity (p < .05). Furthermore, soil properties selected to account for soil erodibility varied with rainfall intensity. The integrated data indicated that soil erodibility was mainly influenced by clay minerals at the region scale and soil degradation degree at the pedon scale. [ABSTRACT FROM AUTHOR] more...- Published
- 2018
- Full Text
- View/download PDF
33. Integrating Soil Compaction Impacts of Tramlines Into Soil Erosion Modelling: A Field-Scale Approach
- Author
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Philipp Saggau, Michael Kuhwald, and Rainer Duttmann
- Subjects
water erosion ,wheel tracks ,physical-based model ,Weichselian till ,erosion prediction ,management effects ,soil degradation ,soil conservation ,erosion and sediment control ,Physical geography ,GB3-5030 ,Chemistry ,QD1-999 - Abstract
Soil erosion by water is one of the main soil degradation processes worldwide, which leads to declines in natural soil fertility and productivity especially on arable land. Despite advances in soil erosion modelling, the effects of compacted tramlines are usually not considered. However, tramlines noticeably contribute to the amount of soil eroded inside a field. To quantify these effects we incorporated high-resolution spatial tramline data into modelling. For simulation, the process-based soil erosion model EROSION3D has been applied on different fields for a single rainfall event. To find a reasonable balance between computing time and prediction quality, different grid cell sizes (5, 1, and 0.5 m) were used and modelling results were compared against measured soil loss. We found that (i) grid-based models like E3D are able to integrate tramlines, (ii) the share of measured erosion between tramline and cultivated areas fits well with measurements for resolution ≤1 m, (iii) tramline erosion showed a high dependency to the slope angle and (iv) soil loss and runoff are generated quicker within tramlines during the event. The results indicate that the integration of tramlines in soil erosion modelling improves the spatial prediction accuracy, and therefore, can be important for soil conservation planning. more...
- Published
- 2019
- Full Text
- View/download PDF
34. Soil erosion assessment in a humid, Eastern Himalayan watershed undergoing rapid land use changes, using RUSLE, GIS and high-resolution satellite imagery
- Author
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Chatterjee, Nirmalya
- Published
- 2020
- Full Text
- View/download PDF
35. Evaluating the BANCS Streambank Erosion Framework on the Northern Gulf of Mexico Coastal Plain.
- Author
-
McMillan, Mitchell, Liebens, Johan, and Metcalf, Christopher
- Subjects
- *
SOIL erosion , *SEDIMENTS , *PLAINS , *EROSION , *COASTAL plains - Abstract
The Bank Assessment of Nonpoint source Consequences of Sediment ( BANCS) framework allows river scientists to predict annual sediment yield from eroding streambanks within a hydrophysiographic region. BANCS involves field data collection and the calibration of an empirical model incorporating a bank erodibility hazard index ( BEHI) and near-bank shear stress ( NBS) estimate. Here we evaluate the applicability of BANCS to the northern Gulf of Mexico coastal plain, a region that has not been previously studied in this context. Erosion rates averaged over two years expressed the highest variability of any existing BANCS study. As a result, four standard BANCS models did not yield statistically significant correlations to measured erosion rates. Modifications to two widely used NBS estimates improved their correlations ( r2 = 0.31 and r2 = 0.33), but further grouping of the data by BEHI weakened these correlations. The high variability in measured erosion rates is partly due to the regional hydrologic and climatic characteristics of the Gulf coastal plains, which include large, infrequent precipitation events. Other sources of variability include variations in bank vegetation and the complex hydro- and morphodynamics of meandering, sand bed channels. We discuss directions for future research in developing a streambank erosion model for this and similar regions. [ABSTRACT FROM AUTHOR] more...
- Published
- 2017
- Full Text
- View/download PDF
36. Modelling Soil Detachment of Different Management Practices in the Red Soil Region of China.
- Author
-
Wang, Yi, Cao, Longxi, Fan, Jianbo, Lu, Huizhong, Zhu, Yayun, Gu, Yalan, Sun, Bo, and Liang, Yin
- Subjects
SOIL degradation ,SOIL erosion ,RED soils - Abstract
Soil erosion from cropland is a primary cause of soil degradation in the hilly red soil region of China. Soil characteristics and the resistance of soil to erosion agents can be improved with appropriate management practices. In this study, hydraulic flume experiments were conducted to investigate the effects of five management practices [manure fertilizer (PM), straw mulch cover (PC), peanut-orange intercropping (PO), peanut-radish rotation (PR) and traditional farrow peanut (PF)] on soil detachment. Based on the results, three conservation management practices (PC, PM and PO) increased the resistance of soil to concentrated flow erosion. The rill erodibility of different treatments was ranked as follows: PC (0·001 s m
−1 ) < PM (0·004 s m−1 ) < PO (0·007 s m−1 ) < PF (0·01 s m−1 ) < PR (0·027 s m−1 ). The rill erodibility was affected by soil organic content, aggregate stability and bulk density. The soil detachment rate was closely correlated with the flow discharge and slope gradient, and power functions for these two factors were developed to evaluate soil detachment rates. Additionally, the shear stress, stream power and unit stream power were compared when estimating the soil detachment rate. The power functions of stream power and shear stress were equivalent, and both are recommended to predict detachment rates. Local soil conservation can benefit from the results of this study with improved predictions of erosion on croplands in the red soil region of China. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR] more...- Published
- 2017
- Full Text
- View/download PDF
37. Sand erosion prediction models for two-phase flow pipe bends and their application in gas-liquid-solid multiphase flow erosion.
- Author
-
Peng, Wenshan, Cao, Xuewen, Ma, Li, Wang, Ping, Bian, Jiang, and Lin, Cunguo
- Subjects
- *
MATERIAL erosion , *MULTIPHASE flow , *TWO-phase flow , *PIPE flow , *PIPE bending , *PREDICTION models - Abstract
In the field of petrochemical industry, the pipe bend of pipeline transportation system is very vulnerable to the sand particle erosion. In this paper, the influence of fluid factor, solid particle factor and pipe size factor on the sand erosion rate of two-phase flow pipe bend is studied by using the fluid computational dynamics (CFD) method. The influence degree of different factors on the erosion rate and the prediction models of the maximum erosion rate are obtained by using grey correlation analysis and data fitting method. The comparison between the experimental data and the prediction models shows that the prediction results agree well with the experimental data. Furthermore, the two-phase flow erosion rate prediction models are applied to the gas-liquid-solid multiphase flow erosion conditions, and their prediction accuracy and adaptability are analyzed. This study can provide ideas and prediction methods for sand erosion prediction in gas-liquid-solid multiphase flow pipeline. The erosion prediction model agrees well with the experiment data. [Display omitted] • Two-way coupling method was employed in two-phase flow erosion simulation. • The influence of different erosion factors on pipe bend erosion was ranked. • The erosion prediction models of gas-solid flow and liquid-solid flow are established. • Two-phase flow erosion prediction models were applied and evaluated in gas-liquid-solid multiphase flow erosion conditions. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
- Full Text
- View/download PDF
38. The development of U. S. soil erosion prediction and modeling
- Author
-
John M. Laflen and Dennis C. Flanagan
- Subjects
Universal Soil Loss Equation ,Water Erosion Prediction Project ,Soil erosion ,Erosion prediction ,History of erosion prediction ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
Soil erosion prediction technology began over 70 years ago when Austin Zingg published a relationship between soil erosion (by water) and land slope and length, followed shortly by a relationship by Dwight Smith that expanded this equation to include conservation practices. But, it was nearly 20 years before this work's expansion resulted in the Universal Soil Loss Equation (USLE), perhaps the foremost achievement in soil erosion prediction in the last century. The USLE has increased in application and complexity, and its usefulness and limitations have led to the development of additional technologies and new science in soil erosion research and prediction. Main among these new technologies is the Water Erosion Prediction Project (WEPP) model, which has helped to overcome many of the shortcomings of the USLE, and increased the scale over which erosion by water can be predicted. Areas of application of erosion prediction include almost all land types: urban, rural, cropland, forests, rangeland, and construction sites. Specialty applications of WEPP include prediction of radioactive material movement with soils at a superfund cleanup site, and near real-time daily estimation of soil erosion for the entire state of Iowa. more...
- Published
- 2013
- Full Text
- View/download PDF
39. Numerical simulation of solid particle erosion in pipe bends for liquid–solid flow.
- Author
-
Peng, Wenshan and Cao, Xuewen
- Subjects
- *
PETROLEUM industry , *SOLID-liquid interfaces , *EROSION , *EULER-Lagrange system , *PIPE bending , *COMPUTER simulation - Abstract
Erosion caused by solid particles in pipe bends is one of the major concerns in the oil and gas industry which may result in equipment malfunction and even failure. In this work, a two-way coupled Eulerian–Lagrangian approach is employed to solve the liquid–solid flow in the pipe bend. Five different erosion models and two particle-wall rebound models are combined to predict the erosion rate. The most accurate model is chosen to calculate the effects of a range of parameters on erosion after comparing the predicted results with the experimental data. Further, the relationship between the Stokes number and the maximum erosion location is also assessed. It is found that although all these erosion models generate qualitatively similar erosion patterns, the Erosion/Corrosion Research Center (E/CRC) erosion model with the Grant and Tabakoff particle-wall rebound model produces results that are closest to the experimental data. Sequence of the influence of different parameters on erosion from the highest to the lowest is obtained: pipe diameter, inlet velocity, bending angle, particle mass flow, particle diameter, and Mean Curvature Radius/Pipe Diameter (R/D) ratio and bend orientation. Additionally, the relationship between Stokes number and the dynamic movement of the maximum erosion location is presented which can be used to predict the maximum erosion location for different operating conditions. Three collision mechanisms are proposed to explain how the changes of Stokes numbers influence the erosion location. [ABSTRACT FROM AUTHOR] more...
- Published
- 2016
- Full Text
- View/download PDF
40. Validation of a probabilistic post-fire erosion model.
- Author
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Robichaud, Peter R., Elliot, William J., Lewis, Sarah A., and Miller, Mary Ellen
- Subjects
EROSION ,RUNOFF ,HYDROLOGIC cycle ,SEDIMENTS ,SNOWMELT ,RAINFALL - Abstract
Post-fire increases of runoff and erosion often occur and land managers need tools to be able to project the increased risk. The Erosion Risk Management Tool (ERMiT) uses the Water Erosion Prediction Project (WEPP) model as the underlying processor. ERMiT predicts the probability of a given amount of hillslope sediment delivery from a single rainfall or snowmelt event on unburned, burned and recovering forest, range and chaparral hillslopes and the effectiveness of selected mitigation treatments. Eight published field study sites were used to compare ERMiT predictions with observed sediment deliveries. Most sites experienced only a few rainfall events that produced runoff and sediment (1.3-9.2%) except for a California site with a Mediterranean climate (45.6%). When sediment delivery occurred, pooled Spearman rank correlations indicated significant correlations between the observed sediment delivery and those predicted by ERMiT. Correlations were ρ = 0.65 for the controls, ρ = 0.59 for the log erosion barriers and ρ = 0.27 (not significant) for the mulch treatments. Half of the individual sites also had significant correlations, as did 6 of 7 compared post-fire years. These model validation results suggest reasonable estimates of probabilistic post-fire hillslope sediment delivery when compared with observations from eight field sites. [ABSTRACT FROM AUTHOR] more...
- Published
- 2016
- Full Text
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41. Numerical prediction of erosion distributions and solid particle trajectories in elbows for gas–solid flow.
- Author
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Peng, Wenshan and Cao, Xuewen
- Subjects
GAS flow ,EROSION ,PARTICLE tracks (Nuclear physics) ,GAS-solid interfaces ,GAS industry ,PIPE bending ,COMPUTATIONAL fluid dynamics - Abstract
Erosion caused by particles in pipe bends is a serious problem in the oil and gas industry, which may cause equipment malfunction and even failure. The majority of this work studies the particle trajectories and erosion distributions in pipe bends under different influencing factors by using the computational fluid dynamics (CFD) method. A two-way coupled Eulerian-Lagrangian approach is employed to solve the gas–solid flow in the pipe bend. Eight commonly used erosion models and two particle-wall rebound models are combined to predict the erosion rate on the 90° elbows. The Det Norske Veritas (DNV) erosion model with the Forder et al. particle-wall rebound model is finally chosen as a sample to develop the new CFD-based erosion model after comparing with the experimental data. The accuracy of this presented model is assessed by the experimental data available in previous literature for a range of flow conditions. Good agreement between the predictions and experimental data is observed. Further, the erosion distributions and particle trajectories in pipe bends under different flow velocity, particle mass flow rate and mean curvature radius to diameter (R/D) ratio and pipe diameter are investigated by applying the presented model. The results show that totally two types of erosion scars and three types of particle collisions occur at the elbows with different erosion parameters. These two types of scars may occur alone or occur together due to the combined effect of the particle collisions. Finally, two equations for predicting the maximum erosion location are obtained considering the pipe bend orientation, the particle diameter and the R/D ratio. [ABSTRACT FROM AUTHOR] more...
- Published
- 2016
- Full Text
- View/download PDF
42. Reliability of soil erodibility estimation in areas outside the US: a comparison of erodibility for main agricultural soils in the US and China.
- Author
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Zhang, Keli, Lian, Li, and Zhang, Zhuodong
- Abstract
Soil erodibility (K), which has important influences on the accuracy of soil loss prediction, is a critical factor in the universal soil loss equation (USLE) and the models modified from it. As an effective tool to estimate soil loss, USLE has been widely applied in the US and around the world. Since the 1980s, the USLE framework for soil erosion prediction and assessment has been adopted in China. During its application in China, it has been noticed that the K values appear to be considerably lower than those in the US. This fact means that the estimated values of soil erodibility from existing methods, such as the nomograph-based database in the US, might be unreliable for their application in China and other areas. In this study, the K values for the main agricultural soils in China with those in the US were systematically compared based on the database from field runoff plots. Possible reasons for the differences were analyzed, and the reliability of soil erodibility estimation in areas outside the US was assessed. Results show that the average K factor for soils in the US is two to three times greater than that in China. For two typical stations with similar soil types located in the US and China, soil loss per rainfall erosivity is higher in the US than in China, although erosivity for the given rainfall in the US is sometimes smaller than that in China. There might be a great bias in soil loss prediction in China if the K value formulas derived from the database of the United States are used directly. This implies that the erodibility estimation formula currently used in the USLE model may need to be verified and revised. [ABSTRACT FROM AUTHOR] more...
- Published
- 2016
- Full Text
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43. A mixed Euler–Euler/Euler–Lagrange approach to erosion prediction.
- Author
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Messa, Gianandrea Vittorio, Ferrarese, Giacomo, and Malavasi, Stefano
- Subjects
- *
EULER-Lagrange equations , *EROSION , *PREDICTION models , *PETROLEUM industry , *COMPUTATIONAL fluid dynamics , *JETS (Fluid dynamics) - Abstract
Providing quantitative assessment of erosion in the various parts of a piping system is of considerable importance in the oil&gas industry. Field and lab erosion testing are extremely onerous and, for this reason, this task is typically achieved by means of algebraic erosion correlations in conjunction with CFD two-phase models based on the Euler–Lagrange approach for flow computation. However, the high computational burden makes this approach onerous even for relatively simple benchmark cases, and it cannot be actually applied in many practical applications. In this paper, we present an innovative approach to erosion prediction, which relies on the combined use of Euler–Euler and Euler–Lagrange CFD two-phase models. The strength of the proposed approach, compared to the standard practice, resides in its numerical efficiency, arising from the fact that the Lagrangian description of the solid phase is restricted to certain subdomains bounded by the surfaces most vulnerable to erosion. The outcomes of two application cases, namely an abrasive jet impingement test and a simplified model of a needle and seat choke valve, demonstrate that the new approach allows considerable reduction of the computational burden for particle tracking and wear estimation. This will open the way for addressing more complex flows of considerable interest in practical applications, which are actually precluded at present. [ABSTRACT FROM AUTHOR] more...
- Published
- 2015
- Full Text
- View/download PDF
44. The erosive growth of hillside gullies.
- Author
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Rose, Calvin W., Yu, Bofu, Ward, Douglas P., Saxton, Nina E., Olley, Jon M., and Tews, Errol K.
- Subjects
SOIL erosion ,RUNOFF ,LANDFORMS ,LANDSCAPES ,EROSION ,DIGITAL elevation models ,OPTICAL radar - Abstract
ABSTRACT The rate of erosion of hillside gullies depends both on gully flow characteristics and the resistance offered by the gully soil profile to erosion. This paper describes a method for quantifying a physically-based resistance measure, illustrated by application to a gully feeding sediment into the Bremer River, southeast Queensland, Australia. The dynamics of discharge down the gully during runoff events is the driver of erosion, but this was unknown. A new method is described whereby this unmeasured flow can be estimated using data on rainfall rate and river gauge monitoring. The data collected on the gully was the increase in dimensions and volume (and so soil loss) over a two year period. This information was obtained from a digital elevation model (DEM) of the catchment, derived from Light Detection and Ranging (LiDAR) observations made at either end of the two year period. The soil profile resistance characteristic evaluated is the energy required to erode a unit mass of soil from the gully walls, a physically-defined parameter, J, present in flow-driven erosion theory, which was adapted and applied to predict soil loss from the Bremer River gully. The value of J was evaluated by equating predicted to measured gully soil loss over the two year period using two alternative descriptions of gully cross-section. Firstly a realistic gully shape description was used, made possible by LiDAR data, yielding J = 405.5 J/kg. Secondly, in order to allow use of more widely-available aerial photography for such studies, the simplifying assumption of a semi-circular gully shape was made, yielding J = 455 J/kg. Allowing a ±30% error in estimated effective runoff rate for this ungauged gully, the estimated J value would have an uncertainty of +1%/−7% using the actual gully geometry. The assumptions made in estimating J are discussed, and possible applications of this information listed. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR] more...
- Published
- 2014
- Full Text
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45. Numerical prediction of the erosion due to particles in elbows.
- Author
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Pereira, Gabriel Chucri, de Souza, Francisco José, and de Moro Martins, Diego Alves
- Subjects
- *
PETROLEUM industry , *PREDICTION models , *EROSION , *OIL spills , *CATALYSTS , *GAS-solid interfaces - Abstract
Erosion by particles in process equipment is one of the major concerns in the oil industry. The transportation and processing of oil and gas may involve eroding particles, such as sand and catalyst, which can cause damage to the process equipment parts. Consequently, undesired maintenance operations are required, leading to unnecessary costs. Also, there exists a risk of oil spill, which is extremely hazardous to the environment. This work is related to the investigation of numerical models for predicting erosion due to particles in an elbow pipe with a 90-degree curvature angle. Wear can be easily identified in such geometry, which is commonly encountered in the oil industry. Four different correlations for the erosion rate were experimented with, namely Ahlert, Neilson and Gilchrist, Oka and Zhang models. The input parameters for these empirical formulas were obtained from accurate CFD models for the gas–solid flow within the bend. In order to assess the quality of the numerical predictions of the erosion rate, experimental data was used. The effect of numerical parameters such as the number of computational particles, as well as the models for the coefficients of restitution and friction and surface roughness, was evaluated. In general, it was found that the experimental correlations yield substantially different values for the penetration ratio, although the erosion patterns generated by all of them are qualitatively similar. Despite the complexity of the phenomenon, the Oka model produced results in close agreement with the experiments, suggesting that it can be successfully employed in engineering applications along with accurate gas–solid simulations. [ABSTRACT FROM AUTHOR] more...
- Published
- 2014
- Full Text
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46. Quantifying the reduction in cavitation-induced erosion damage in the Spallation Neutron Source mercury target by means of small-bubble gas injection.
- Author
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Jiang, Hao, Winder, Drew, McClintock, David, Bruce, Doug, Schwartz, Richard, Kyte, Matt, and Carroll, Timothy
- Subjects
- *
GAS injection , *CAVITATION erosion , *NEUTRON sources , *EROSION , *DAMAGE models , *SERVICE life , *MERCURY - Abstract
A model developed to represent the progress of erosion damage in liquid-metal spallation target vessels was modified to incorporate the effect of gas injection on the erosion rate. The liquid mercury target system for the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory now operates with helium gas injection to reduce target vessel fatigue stress and cavitation-induced erosion damage. Erosion damage is a primary degradation phenomenon affecting the service life of SNS target vessels, and cavitation mitigation techniques, such as small-bubble gas injection, have been implemented to reduce damage and extend target lifetimes. Erosion depths in samples removed from SNS targets after operation were measured using laser line scanning. These measurements confirmed that gas injection reduced erosion damage. However, quantifying the damage reduction due to gas injection was complicated by variations in lifetime, power, and gas injection rates between different targets. In this study, the operating power and gas injection rate of targets were incorporated into an erosion damage prediction model to quantify their effects on erosion damage reduction. Values of a power scaling factor, β , were calculated by comparing modeled with measured erosion damage. These values indicate that the use of gas injection at the SNS reduced damage to a level equivalent to operating targets without gas injection at 35–47% of the actual beam power. To account for the gas injection effect on the cavitation damage, a simple exponential form based on analysis of the scaling factor β was developed to incorporate the gas rate history with a scaling factor γ in the erosion damage modeling. • Erosion depths in SNS target samples were measured using laser line scanning. • Erosion damage reduction was quantified for the effect of gas injection. • The power and gas injection rate of targets were incorporated into erosion damage model. • Damage reduction is equivalent to power reduction to 35–47% of actual beam power. [ABSTRACT FROM AUTHOR] more...
- Published
- 2022
- Full Text
- View/download PDF
47. Experimental investigation of local scour around cylindrical pile foundations in a double-layered sediment under current flow.
- Author
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Wang, Chen, Yuan, Ye, Liang, Fayun, and Tao, Junliang
- Subjects
- *
MECHANICAL behavior of materials , *SEDIMENTS , *OCEAN bottom , *SOIL permeability , *RIVER channels - Abstract
Scour is a natural phenomenon that occurs when the soil around piles erodes, and it is significantly affected by the characteristics of the seabed or riverbed materials, the nearby submerged obstructions, and the water flowing past. Water–sediment interaction is a critical process that may lead to the loss of bed materials and influence the mechanical behavior of foundations. Exploring the scour mechanism is essential for predicting scour depth and designing appropriate countermeasures, especially those that consider essential concepts in geomechanics as well as complex geological conditions. This study presents a series of tests on piles embedded in single- and double-layered sediments that are composed of coarse, medium, and fine sands. The results show that the properties of the overlying soil layer govern the initiation of erosion and the final scour range, while those of the underlying layer determine the final scour depth. As the exposed sediments and their scour resistance at the water–soil interface change during the scour, predictions of scour depth that are merely based on the properties of the surface layer of the sediment may not be accurate. Based on the experimental results, an innovative predictive framework of scour depth was proposed that considers sediments with two layers. • Layered soils are widely distributed, and the influence of changing soil characteristics needs to be considered. • The properties of the overlying soil layer govern the initiation of erosion and the final scour range. • The properties and thickness of the underlying layer determine the final scour depth. • A predictive framework of scour depth was proposed considering double-layered soil conditions. [ABSTRACT FROM AUTHOR] more...
- Published
- 2022
- Full Text
- View/download PDF
48. VÍZMOSÁSOK TERÜLETI ELOSZLÁSA A LEJTŐSZÖG ÉS A KITETTSÉG FÜGGVÉNYÉBEN A MEDVES-VIDÉKEN ÉS A VÖLGYSÉGBEN.
- Author
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JUDIT, SZABÓ and GERGELY, JAKAB
- Subjects
ARROYOS ,EROSION ,SOIL science ,ECOSYSTEMS - Abstract
Gully erosion is one of the major threats to soil resources in Hungary, and may impair their ability to deliver a range of ecosystem goods and services. This study elaborates a model for mapping gully erosion hazard in two Hungarian microregions (Medves and Volgység) using spatial database and GIS. Slope, soil and land cover parameters were combined to create erosion risk maps. The SRTM, the CORINE land cover database and the Hungarian agro-topographi- cal database, the AGROTOPO were available from both regions and used in the study. In the Medves microregion most of the gullies are located on steep (17%<) N-NW slopes, meanwhile in the VOlgyseg gentle (5-17%) S-SW slopes are more common. Thus, among the important factors of slope inclination (Medves) the parameters like arable land and bess covered areas on gentle slope surfaces (Volgység) also favour erosion. Erosion risk mapping is a very useful tool to identify areas for soil conservation planning and sustainable management. Further research in different regions is needed to verify and improve our model of estimating gully erosion. [ABSTRACT FROM AUTHOR] more...
- Published
- 2013
49. Comparison of soil erodibility factors in USLE, RUSLE2, EPIC and Dg models based on a Chinese soil erodibility database.
- Author
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Wang, Bin, Zheng, Fenli, and Römkens, MathiasJ. M.
- Subjects
- *
SOIL erosion , *LAND resource , *UNIVERSAL soil loss equation , *REVISED Universal Soil Loss Equation (RUSLE) , *RUNOFF , *MULTIPLE regression analysis , *COMPARATIVE studies - Abstract
Soil erodibility (K-value) is a key parameter in erosion prediction and is important for conservation planning in the face of a rising need for protecting the limited land resources. This study investigated the predictive capability of theK-value estimated by Universal Soil Loss Equation (USLE), Revised Universal Soil Loss Equation (RUSLE), Erosion Productivity Impact Calculator (EPIC) and Dg models for different soil regions using a Chinese soil erodibility database covering 51 natural runoff plots. Model performance was evaluated usingR2(coefficient of determination), relative error (RE), Nash–Sutcliff efficiency (NSE) andPvalue (Mann–WhitneyUtest) statistics. The results showed that the existing four models overestimated almost all theK-values for the Chinese erodibility database, with most observed values concentrated in the range of 0.015–0.035. Without calibration, only the USLE and Dg models could be reliable and directly applied for the black soil region and the loess soil region, respectively. The Dg–OM model (R2=0.67,n=32) was established by the non-linear best fitting techniques of multiple regression. In the Dg–OM model,K-values accounted for the vibration in a combination of theDg(geometric mean diameter) and OM (soil organic matter). NSE,R2and the average RE was 0.94, 0.67 and 9.5% for the Dg–OM model's calibration based on the Chinese erodibility database; similar results were found for the validation process, with NSE of 0.93,R2of 0.66 and average RE of 6.5%. The model performances showed that the Dg–OM model reached ‘good’ satisfactory level. Compared with the four existing erodibility models, the Dg–OM model permitted the best parameterization and accuracy, and was proved to be suitable for estimating soil erodibility values in China. [ABSTRACT FROM PUBLISHER] more...
- Published
- 2013
- Full Text
- View/download PDF
50. Performance comparison and erosion prediction of jet pumps by using a numerical method
- Author
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Song, Xue-Guan, Park, Joon-Hong, Kim, Seung-Gyu, and Park, Young-Chul
- Subjects
- *
PERFORMANCE , *COMPARATIVE studies , *EROSION , *FLUID dynamics , *JET pumps , *COMPUTER simulation - Abstract
Abstract: The jet pump has been studied and improved continuously for many years. The improvement of the jet pump’s efficiency brings economic advantages. In this study, the commercial software ANSYS CFX is firstly employed to investigate and compare the performance of a newly designed jet pump with two classical types. Performances such as mass flow ratio, pressure ratio and efficiency are compared at three types of working condition. It’s found that the newly designed type of jet pump has the best performance under the designed working condition. Then, this paper presents erosion evaluation for the new type of jet pump by using a CFD-based particle erosion model. The similar CFD model is conducted for the calculations of the fluid velocity field. A particle-tracking model of the sand particles is used to track the trajectory of sand particles, and Finnie’s model is used as the erosion prediction model. The results demonstrate the erosion intensity and distribution in the jet pump and show the effect of the bended pipe on the erosion in the suction chamber. The results show that numerical simulation can be very helpful for the erosion prediction and further optimization of the jet pump even though the accuracy has not been validated for this study. [Copyright &y& Elsevier] more...
- Published
- 2013
- Full Text
- View/download PDF
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