Erosion Analysis for the Carcass of Unbonded Flexible Pipes

At present, unbonded flexible pipes (UFPs) are widely used in ocean engineering for oil exploitation. In practice, erosion will lead to premature failure of pipelines. There is a lack of researches on the erosion of interlock carcass of UFPs. As the authority in the field of offshore engineering, DET NORSKE VERITAS(DNV) suggested a way to estimate the erosion rate of pipes, however, it does not study the erosion mechanism of UFPs in detail and the relevant parameters are not specified. This paper modifies erosion prediction of UFPs based on a user defined Fortran subroutine. A series of CFD simulations have been conducted, and three widely used erosion models were used for comparative verification. The effect of geometric shape on erosion rate has been carefully studied. and the effect of velocity, particle size, and concentration are also studied to verify the reliability of the improved model.

REVIEW OF THE KINEROS MODEL FOR PREDICTING THE EFFECT OF LAND USE ON THE SURFACE RUN-OFF

Topics protection of catchment area relating to land use to support sustainability and environmental capacity is an interesting topic to be discussed scientifically. The increasing frequency of floods, droughts, landslides, and water crises are recently showed that the management of watersheds (DAS) has not been optimal. The Kineros Model for predicting the effect of land use on the surface run-off need to be improve in application. This paper has shown that the protection of natural ecosystems has a better impact than infrastructure development, especially about preventing inundation due to high surface runoff. This journal will strengthen the need for watershed-scale erosion prediction analysis because of its ability to define strategic areas of policy intervention to enable policymakers and the community to carry out recovery programs/activities more effectively and focused. The accuracy of determining the location of the policy has an impact on cost, time, and energy efficiency. Spatial calculation/analysis models combined with social and economic approaches will create a balanced and integrated sustainable development. The reviewer suggests a realistic combination of approaches, which combines the spatial aspects and technocratic calculations aspects of economic instruments that become balanced in a multidisciplinary concept.

Forecasting East Belitung Regency Rainfall Data by Reviewing Heteroscedasticity

East Belitung Regency is one of the regencies located on Belitung Island. East Belitung Regency has a tropical and wet climate with a fairly high variation of rainfall. Rainfall forecasting is an important thing to model because of the many uses of rainfall forecasting results such as irrigation planning, flood prediction, erosion prediction and others. This study aims to predict rainfall for the next 5 years by using a time series model by reviewing the heteroscedasticity of the data. From the results of the analysis of rainfall in East Belitung Regency with a seasonal pattern. The best model used is ARIMA (0, l, l)(2, l, l)12 with insignificant heteroscedasticity.

Soil erosion prediction using USLE model in Cangkringan micro watershed model, Yogyakarta

Land use that is not in accordance with ecological principles causes’ excessive soil erosion. Soil erosion has an impact on decreasing soil productivity, increasing critical land and causing land degradation. It is essential to predict the amount of soil lost due to soil erosion to determine the conservation efforts applied to suppress the erosion rate. The estimation of erosion in this study using the USLE model, using 5 factors, namely erosivity (R), erodibility (K), slope length (LS), crop management (C), and soil conservation (P). The results showed that the level of erosion hazard in Cangkringan Micro Watershed Model consisted of 5, namely very light covering an area of 29.14 ha (2.15%), mild covering an area of 642.31 ha (47.44%), moderate covering an area of 545.62 ha (40.30%), heavy area of 129.00 ha (9.53%) and very heavy area of 7.94 ha (0.58%).

Mathematical Multiobjective Optimization for Metal Hip Arthroplasty with Medical Physics Applications

Total hip metal arthroplasty (THA) model-parameters for a group of commonly used ones is optimized and numerically studied. Based on previous ceramic THA optimization software contributions, an improved multiobjective programming method/algorithm is implemented in wear modeling for THA. This computational nonlinear multifunctional optimization is performed with a number of THA metals with different hardnesses and erosion in vitro experimental rates. The new software was created/designed with two types of Sytems, Matlab and GNU Octave. Numerical results show be improved/acceptable for in vitro simulations. These findings are verified with 2D Graphical Optimization and 3D Interior Optimization methods, giving low residual-norms. The solutions for the model match mostly the literature in vitro standards for experimental simulations. Numerical figures for multifunctional optimization give acceptable model-parameter values with low residual-norms. Useful mathematical consequences/calculations are obtained for wear predictions, model advancements and simulation methodology. The wear magnitude for in vitro determinations with these model parameter data constitutes the advance of the method. In consequence, the erosion prediction for laboratory experimental testing in THA add up to the literature an efficacious usage-improvement. Results, additionally, are extrapolated to efficient Medical Physics applications and metal-THA Bioengineering designs.

Dampak Perubahan Curah Hujan Terhadap Tingkat Kerentanan Erosi Tanah Di Sub DAS Merawu, Jawa Tengah

This research was held to estimate rainfall and change in soil erosion vulnerability from 2020 to 2050 in Merawu Sub-Watershed, Banjanegara District with RCP 2.6, 4.5 and 8.5. The RCP is an overview of the concentration trends for greenhouse gases, aerosols and land use change created by the climate modeling community. Rainfall prediction was generated from SDSM Software and combined with USLE to predict soil erosion in ArcGIS 10.4. Changes in rainfall intensity are an important factor in changes of soil erosion rates because the kinetic energy of falling rainwater can cause soil erosion.The results showed rainfall in Banjarnegara Station at 2020-2050 with RCP 2.6,4.5 and 8.5 were increasing by +0,26%; +0,60%; +0,52%, while in Kalisapi Station were decreasing by -1,54%; -1,65% dan -2,20%. The change of soil erosion vulnerability prediction showed that soil erosion in Sub-DAS Merawu at 2020-2050 with RCP 2.6,4.5 and 8.5 in very light category were -0,02%;-0,02%;-0,03%, light category were -0,17%;-0,17%;-0,17%, moderate category -0,05%;-0,05%;-0,04%, heavy category -0,26%;-0,35%;-0,37%, and very heavy category were +1,46%;+1,88%;+1,95%. While the average soil erosion prediction at RCP 2.6, 4.5 and 8.5 were +0,86, +1,19% and +1,03%, respectively. Keywords: soil erosion prediction, rainfall prediction, SDSM Software, Sub-DAS Merawu

Improved Prediction of Sand Erosion by Accurate Particle Shape Representation in CFD-DEM Modelling

Predicting accurate erosion rate due to sand particles in oil and gas production is important for maintaining safe and reliable operations while maximizing output efficiency. Computational Fluid Dynamic (CFD) is a powerful tool for erosion prediction as it provides detailed erosion pattern in complex geometry. In an effort to improve accuracy of erosion prediction, this paper proposes an algorithm to accurately represent particle shape in CFD erosion simulation through coupling with Discrete Element Method (DEM) for non-spherical shape particles. The fluid motions are predicted by CFD and the particle movements (including particle-particle and particle-wall collisions) and fluid-particle interaction are calculated using DEM. It is widely known that sand particles are of finite volume with a non-spherical shape, accurate representation of sand particles is important in CFD modelling for accurate prediction of erosion rate. Traditional CFD approach usages lagrangian tracking of sand particles through Discrete Phase Model (DPM), where a particle is assumed as a point mass for the calculation of trajectory and particle-wall interaction. Particle impact velocity and impact angle are important parameter in determining erosion. Assumption of point mass in DPM approach, will not capture particle-wall interaction accurately especially when particles are of non-spherical in shape. In additional, DPM approach ignores particle-particle interactions. This can adversary affect the accuracy of erosion predictions. Integrating non-spherical DEM collision algorithm with CFD erosion simulation, will overcome these limitations and improve erosion predictions. Benefits of this CFD-DEM erosion modelling was demonstrated for gas-solid flow in a 2" pipework which consists of out-of-plane elbows in series and blind-tees. Experimental dataset [1] for erosion pattern on each elbow was used to validate CFD predictions. Three different erosion CFD simulations were performed, traditional DPM based CFD simulation, CFD-DEM simulation for spherical shape particles and CFD-DEM simulation for non-spherical shape particles. CFD-DEM coupled simulations clearly show an improvement on erosion predictions compared to DPM based CFD simulation. Effect of non-spherical shape on rebound angle during particle-wall collision is captured accurately in CFD-DEM simulation. CFD-DEM simulation using non-spherical particle, was able to predict erosion pattern closer to experimental observations. This paper will demonstrate an increase in accuracy of sand erosion prediction by integrating DEM collision algorithm in CFD modelling. The prediction results of elbow erosion subject to a condition of dilute gas-particle flow are validated against experimental data. Improved prediction of erosion risk will increase the safety and reliability of oil & gas operations, while maximizing output efficiency.

Rainfall Erosion Predictions for Artificial High-Filled Embankment with Reinforcement

In recent years, rainstorm disasters caused by global warming have frequently occurred in China. It has caused serious damage to artificial high embankments. In this paper, the influence of rainfall intensity, slope, and reinforced layers on the erosion and destruction of the artificial high embankment is deeply analyzed. Through the model test, the rainfall erosion prediction model is established. The results show that (1) the gully width, depth, and erosion amount increased with the increase in rainfall intensity and slope and decreased with the increase in reinforcement layers; (2) the final ditch shape of the embankment is influenced by steel bars; and (3) according to the model test data, the mathematical model of dike scouring is established. Rainfall intensity and the coupling between slope and reinforced layers are considered in the model. It can be used for predicting erosion during rainfall.

Mathematical Standard-Parameters Dual Optimization for Metal Hip Arthroplasty Wear Modelling with Medical Physics Applications

Total hip metal arthroplasty (THA) constitutes an important proportion of the standard clinical hip implant usage in Medical Physics and Biomedical Engineering. A computational nonlinear optimization is performed with two commonly metal materials in Metal-on-Metal (MoM) THA. Namely, Cast Co-Cr Alloy and Titanium. The principal result is the numerical determination of the K adimensional-constant parameter of the model. Results from a new more powerful algorithm than previous contributions, show significant improvements. Numerical standard figures for dual optimization give acceptable model-parameter values with low residuals. These results are demonstrated with 2D and 3D Graphical/Interior Optimization also. According to the findings/calculations, the standard optimized metal-model parameters are mathematically proven and verified. Mathematical consequences are obtained for model improvements and in vitro simulation methodology. The wear magnitude for in vitro determinations with these model parameter data constitute the innovation of the method. In consequence, the erosion prediction for laboratory experimental testing in THA adds valuable information to the literature. Applications lead to medical physics improvements for material/metal-THA designs.