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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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

Abstract: Surface roughness is thought to affect concentrated flow erosion – a major mechanism of soil loss on disturbed rangelands. However, quantifying surface roughness in the field at appropriately fine spatial scales is laborious and the scale at which to conduct meaningful roughness measurements is difficult to discern. Rapid, objective, and repeatable field methods are therefore needed to accurately measure surface roughness across a range of spatial scales to advance our understanding and modeling of concentrated flow erosion processes. Surface roughness can be derived from surface topography mapped at the sub-cm level using a field-portable terrestrial laser scanner (TLS). To test the suitability of terrestrial laser scanning for studying surface roughness effects on erosion processes in rangelands, we used concentrated flow simulation techniques at 8.5m2 plots that were randomly placed at rangeland sites in southeastern Oregon and southwestern Idaho, USA. Local surface roughness (locRMSH) was calculated as the standard deviation of TLS mapped surface heights within moving windows varying in size from 30×30 to 90×90mm. The mean locRMSH of the eroded area and entire plot were negatively correlated (r2 >0.71, RMSE<95.97gmin−1, and r2 >0.74, RMSE<90.07gmin−1, respectively) with concentrated flow erosion. The strength of the locRMSH–erosion relationship and regression model parameters were affected by the moving window size, emphasizing the scale dependence of the locRMSH–erosion relationship. Adjusting locRMSH for slope effects decreased the strength of the locRMSH–erosion relationship from r2 <0.83 to<0.26. Our results indicate that TLS is a useful tool to enhance our current understanding of the effect of surface roughness on overland flow erosion processes and advance hydrologic and erosion model parameter development. Further research is needed to evaluate the locRMSH – concentrated flow erosion relationship over a wider range of soil properties, surface conditions, and spatial extents. [Copyright &y& Elsevier]

Abstract: Erosion–corrosion damage within pipelines and associated fluid handling equipment is prevalent in the oil and gas sector and other process industries where solid-laden flows, such as those involved in the processing of oil sands are found. As a first step towards trying to understand the interactions between erosion and corrosion it is important to understand the erosion damage that occurs as a result of solid particle impact on a surface (usually metal). This paper addresses this in relation to transport of fluids in the oil-sands industry. A method for predicting erosion damage has been developed, using a combination of standard laboratory based experiments and Computational Fluid Dynamic (CFD) simulations. This paper provides validation of such an approach: (i) a universal wear map is generated for the material in question using a jet impingement test (JIT) to generate a wear scar. The local wear rate from this is interpreted using a CFD simulation of the test to generate a map giving local wear as a function of particle impact velocity and angle; (ii) a CFD solution is calculated for a series of different erosion configurations giving the particle impact data at each point on the surface. The wear map from the first stage is then used to give the local wear rate. The power of this method is that once a material-specific map has been generated then wear on any geometry can be calculated through the simulation of flow using CFD. [Copyright &y& Elsevier]

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]

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]

Abstract: An agricultural watershed generally consists of two land use categories, farmland and the unpaved road or path networks with different traffic frequency and size. Road surfaces are quite different from farmland soil in physical properties, resulting in it''s distinguish production transportation process. Hydraulic flume experiments were conducted with the flow discharges ranging from 1 to 5 L s−1 and the slope gradients ranging from 8.8% to 46.6% to simulate the soil detachment process on a road surface and to develop tools in order to calculate detachment rates occurring on that road surfaces. The results illustrate that road surfaces behave characteristically in the runoff detachment and sediment delivery process due to the difference in the bulk density and functions of agricultural soils. The soil detachment rate is closely related to flow depth, slope gradient and other hydraulic parameters such as shear stress, stream power and unit stream power. Multiple non-linear regression analyses indicate that detachment rates for all roads can be accurately predicted by power functions of flow depth and slope gradient. According to the experimental results, stream power was suggested as an indicator to estimate soil detachment rate instead of shear stress in soil erosion models. However, considering the simplicity and availability, power function of flow depth and slope gradient is also recommended to predict detachment rate on the road surfaces. [Copyright &y& Elsevier]

Abstract: Coastal mapping, using various data capture and feature extraction techniques, has furthered understanding of trends in shoreline evolution by allowing calculation of accurate historic rates of change that subsequently enable the prediction of future shoreline positions through different modelling procedures. The results have helped influence coastal policy formulation and promoted the development of sustainable management practices in coastal regions throughout the developed world. However, sustainable coastal management is rarely practiced in developing countries, one of the fundamental reasons for this being a general lack of reliable and accurate historic data on shoreline position. Previous studies on the Ghanaian coastal region of Accra, where accurate and reliable geospatial data for analysis is scarce, have reported erosion rates of anything between two and eight metres per year. This high level of inconsistency in reported rates has hindered effective and sustainable coastal management. The research reported in this paper addresses this issue, using mapping data from 1904, 1974, 1996 and 2002 to estimate, by linear regression, shoreline recession in the Accra region. Predictions for the next 250 yr were then undertaken using a variety of techniques ranging from a process-based numerical model, SCAPE, to geometric approaches including historical trend analysis, the modified Bruun model and Sunamura’s shore platform model. Uncertainties in the various input data were accounted for, including historic recession rates, rock strength, sediment content and, importantly, future sea-level rise under different climate change scenarios. The mean historic rate of erosion in the Accra region was found to be 1.13 m/yr(±0.17 m/yr), significantly less than previously reported, though still very high. Subsequent predictions were used to identify a series of significant economic, ecological and social features at risk, and to estimate when they will most likely be lost to erosion if left unprotected. The case study illustrates that, provided suitable predictive models are selected and the uncertainties involved in working with limited data sets are dealt with appropriately, it is possible to provide statistical information in support of sustainable coastal management for developing countries in the face of a changing climate. [Copyright &y& Elsevier]

Soil erosion by water is serious global problem. In Africa, about 5 Mg ha−1 of productive topsoil is lost to lakes and oceans each year. This study was conducted at the Kianjuki catchment in central Kenya to predict annual soil loss using the Revised Universal Soil Loss Equation (RUSLE Version 1.06) to determine the erosion hazard in the area and target locations for appropriate initiation of conservation measures. All factors used in RUSLE were calculated for the catchment using local data. The rainfall erosivity R-factor was 8527 MJ mm ha−1 h−1per year and the annual average soil erodibility K-factor was 0.016 Mg h MJ−1 mm−1. Slopes in the catchment varied between 0 and 53% with steeper slopes having overall LS-values of over 17. The C-factor values were computed from existing cropping patterns in the catchment, including corn–bean (Zea mays–Phaseolus vulgaris) 1-year rotation, coffee (Coffea arabica), and banana (Musa sapientum). Support practice P-factors were from terraces that exist on slopes where coffee is grown. Total annual soil loss predictions varied from one overland flow segment to the next and ranged from 134 Mg ha−1 per year for slopes with average LS-factors of 0–10 to 549 Mg ha−1 per year for slopes with average LS-factors of 20–30, which is more than the estimated soil loss tolerance (T) for the area of 2.2–10 Mg ha−1 per year. Using 3 years of field data, the RUSLE model was able to pinpoint site-specific erosion hazards associated with each overland flow segment in the catchment for different cropping patterns and management practices. This work highlights the severity of erosion in tropical highlands of east Africa and gives suggestions on possible intervention strategies; however, there is still a need for developing more long-term data to validate the model to suit local agro-ecological conditions. [Copyright &y& Elsevier]

Sand screen is frequently used as a sand control device in oil and gas wells to prevent or minimize sand production. However, the sand screen may undergo mechanical erosion due to continuous impingement and passage of sand particles through its apertures. In addition, the design of most sand screens' spacing allows fine particles <44 μm to pass through. According to previous studies, the existence of fines can also lead to erosion failures. In this study, the Eulerian-Lagrangian approach of dense discrete phase model (DDPM) has been used and evaluated for computational fluid dynamics (CFD) based erosion modelling of sand screen erosion because of the entrainment of fine particles in gas flow. Two sand types having different particle size distributions (PSD) and fine concentrations were studied. For the CFD erosion simulation, four erosion models were used, and then the effect of PSD of fines-inclusive sand particles on erosion magnitude has been investigated. The CFD simulation results were validated against the output of a reliable experimental-based correlation. Erosion results using McLaury model showed the least error and good agreement compared to the other models. For the two investigated sand types, using PSD for erosion prediction using CFD resulted in a higher value of maximum erosion when compared with the constant size simulation results. The value of the maximum erosion has increased 105.9% from the constant size results for sand type-I and 82.5% for sand type-II. The paper presents the first-ever comprehensive analysis study of its kind about the effect of fines-inclusive sand on the erosion of sand screen, considering the particle size distribution (PSD). The results of this study revealed the importance of considering erosion caused by fines, especially at high flow velocities. • Dense discrete phase model was used for CFD modelling of sand screen erosion. • Four erosion models were used for erosion prediction for two sand types. • CFD results using McLaury's model showed a good agreement when validated. • Erosion caused by uniform particle size and by considering PSD was found different. • High fine content and high flow velocity cause increase in SAS erosion. [ABSTRACT FROM AUTHOR]

Slurry erosion is an important cause of material failure in the oil and gas industry. Particularly, during hydraulic fracturing, the fracturing pipelines under high internal pressure inevitably suffer from erosion wear. In this study, the erosion tests involving tensile stress were carried out and a new stress-erosion model suitable for high internal pressure was developed based on the experimental data. Then the established erosion model was applied to conduct the numerical simulation to investigate the erosion behaviour in elbows of fracturing pipeline under different conditions. Finally, an intelligent method of erosion prediction was explored using machine learning technology, providing a potential solution in predicting the erosion severity of elbows under high internal pressure. • A new stress-erosion model was proposed based on the erosion testing involving tensile stress. • The erosion behaviour under high internal pressure was investigated through CFD simulation. • Erosion mechanisms under different conditions of fracturing operation were revealed. • GBRT was first used for erosion prediction. [ABSTRACT FROM AUTHOR]

• RUSLE2 driven by stochastic weather generator. • Linking daily rainfall with RUSLE2 erosivity densities. • Using Yu model to generate erosivity for linking CLIGEN with RUSLE2. CLIGEN is a stochastic weather generator that has been used as input to WEPP. Normally, USLE based models predict erosion using parameter values that are long-term averages but RUSLE2 has a facility to predict erosion for single storms through user entered data. This enables CLIGEN to be used as a weather generator for RUSLE2 when EI 30 values for CLIGEN generated rainfall are determined separately. This can be achieved using daily erosivity density (EI 30 per unit quantity of rain) data generated by RUSLE2 for each location or by other methods that have the capacity to determine daily EI 30 values independently of RUSLE2. One such method developed by Yu was compared with the RUSLE2 based method in terms of its ability to predict temporal variations in soil loss during the calendar year from bare fallow and cropped areas. The process of determining EI 30 values by the Yu method involves generating EI 30 values so as to match R -factor values used by RUSLE2. This enables CLIGEN to predict soil loss values that are as useful those generated using RUSLE2 erosivity densities in terms of predicting long-term variations in soil loss during the year. However, CLIGEN does not necessarily produce stochastic rainfall data evenly over decades. Consequently, the process of matching R -factors associated with RUSLE2 with those generated by using CLIGEN should be undertaken using the same time frame as used for obtaining the long-term mean soil loss amounts. [ABSTRACT FROM AUTHOR]

Real industrial examples have been used to evaluate the viability of several cavitation erosion risk indicators (ERIs). Industry standard endurance tests resulted in non-critical cavitation erosion of a shoe and shoe-guide assembly in a high-pressure fuel pump. A design modification was made which eliminated the erosion. Transient CFD simulations of the two designs were run. The distribution and intensity of the resulting ERIs were evaluated against photographic evidence of erosion taken after endurance testing. Details of the component dynamics and the resulting cavitation formation and collapse are presented, along with an analysis of the ERIs for their potential usefulness. Of the 10 ERIs studied, two were found to be particularly good indicators, one of which is newly derived for this research. It is now anticipated that using these ERIs to guide product design and development will save considerable time and cost. [ABSTRACT FROM AUTHOR]

• Soil improvements by roots are different for planted and natural vegetation. • Distributions of root systems reached a steady state after 12 years restoration. • Root length density was the best root predictor for rill detachability and erodibility. • Rill erodibility of rooted-soils decreases exponentially as root length density increases. The objectives of this study were to evaluate different root parameters for estimating rill detachment, and to compare and quantify the effectiveness of planted and natural vegetation on soil physical characteristics and in reducing rill detachment and erodibility. Laboratory-concentrated-flow flume tests were performed under a flow discharge of 3 L min−1 and a slope of 15° with intact soil samples. A silt loam soil (Calcic Cambisol , in Loess Plateau in China) was sampled in 2015 from laboratory with planted ryegrass (Lolium perenne L.) and in 2014 from natural vegetation fields under 12 to 36-a restoration. The results indicated that root length density was the best parameter for estimating the effects of roots on rill detachment and erodibility for both planted ryegrass and natural vegetation, with exponential reduction equations. The exponents were more negative for natural vegetation (−0.411) than for planted species (−0.217) because of the existence of more complex root networks under more diverse natural vegetation. Rill erodibility of soil samples with roots decreased exponentially from the baseline erodibility of the root-free soil as RLD increased. Root systems of the restored natural vegetation ameliorated soil characteristics (bulk density, aggregate stability and organic matter content) more profoundly than those of the laboratory tests due to stronger bonding and binding effects, resulting in a lower absolute soil detachment rate for a given root density. There existed a vertical decay distribution pattern of root densities with soil depth for natural vegetation and planted ryegrass, and this distribution of root systems reached a steady state after 12 years natural vegetation restoration. More vegetation types under more different hydraulic conditions should be evaluated in future studies to provide better scientific bases for modelling their impacts on rill detachment and erodibility. [ABSTRACT FROM AUTHOR]