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Статті в журналах з теми "SCOURING PATTERN"
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Kato, Fuminori, Yoshio Suwa, Kunihiro Watanabe, and Satoshi Hatogai. "MECHANISMS OF COASTAL DIKE FAILURE INDUCED BY THE GREAT EAST JAPAN EARTHQUAKE TSUNAMI." Coastal Engineering Proceedings 1, no. 33 (October 25, 2012): 40. http://dx.doi.org/10.9753/icce.v33.structures.40.
Повний текст джерелаАнотація:
Based on the results of field surveys, coastal dike failures caused by the Great East Japan Earthquake were classified into eight patterns. The results of hydraulic model experiments related to major failure patterns reinforced the proposed failure processes. In addition, the aggregated length of each failure pattern showed that failure from scouring at the landward toe is the dominant failure pattern.
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Lufira, R. D., S. Marsudi, S. Agustien, and A. Khosin. "Determining the Depth of Local Scouring in a Downstream Energy Dissipation in the Physical Model Test." IOP Conference Series: Earth and Environmental Science 930, no. 1 (December 1, 2021): 012022. http://dx.doi.org/10.1088/1755-1315/930/1/012022.
Повний текст джерелаАнотація:
Abstract Karangnongko Weir is planned to be located in the Bengawan Solo River (Lower Solo River Basin) about 15 km downstream of the confluence of Bengawan Solo River with the Madiun River in Ngelo Village, Margomulyo Sub-District, Bojonegoro Regency, and Ngrawoh Village in Kradenan Sub-District, Blora Regency. This study aims to determine the Depth and pattern of scouring in downstream energy dissipation through physical model tests based on initial planning. Downstream protection of energy dissipation in the original design model combines 50 m of riprap rocks and 50 m of riprap concrete for a total length of 100 m of protection. The maximum scouring pattern occurred at elevation + 17.64 m, where the scouring was 4.36 m deep, from the planned essential height of Height 00 m. Thus, the downstream protection of energy dissipation was extended to 112 m in riprap concrete blocks for the final design model. Scouring at the end of riprap was 3.04 m, the original elevation of the river bottom of + 22.00 m, down to + 18.96 m. It is concluded that the protection is effective in reducing scouring by up to 30.27%.
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Paramadita, Tifarah Dayansabila, Nadia Azarine, Aburizal Azhar, and Didit Puji Riyanto. "Local Scouring Visualization of Bed Channel Surface in Hydraulic Structure Using Surfer." Jurnal Teknik Sipil dan Perencanaan 24, no. 2 (October 31, 2022): 140–49. http://dx.doi.org/10.15294/jtsp.v24i2.36499.
Повний текст джерелаАнотація:
Abstract. Water flowing in the river causes a scouring event that occurs at the bed channel. The existence of scouring will increase along with changes in the geometry of the river and obstacles such as the weir which are followed by local scouring around the weir. Local scouring often occurs downstream end of weir sill which weakens its construction. Scouring measurement was conducted to monitor the pattern of scouring that occurs. By using Surfer software, the scouring visualization through the Data Grid and 3D Surface can be seen. In this research, scour monitoring in the laboratory using open channels (flume) and MDO weir with fine aggregate material as the basis of the channel. The retrieval of scouring data was performed after installing fine aggregate and three times variations of flow discharge, then the data were processed using Surfer. The first flow used water level +3.50 with the material carried at 3.77%. The second flow used water level +4.50 with the material carried at 11.16%. The third flow used water level +5.70 with the material carried at 25.46%. So with the continuous method, the total material carried at 36.27% is equivalent to 12575.77 cm3.
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Gao, Pengcheng, Xianyou Mou, and Honglan Ji. "Simulation Study on Local Scour Characteristics of Tandem Bridge Piers in a Straight River under a Changing Environment." Sustainability 15, no. 15 (July 31, 2023): 11776. http://dx.doi.org/10.3390/su151511776.
Повний текст джерелаАнотація:
Hydrodynamics is a common manifestation that causes natural scouring of riverbeds, and it is one of the factors that exacerbate the natural disasters of local scouring of bridge piers, causing sustainability of environmental changes in the water. The evolution pattern and scour characteristics of the bed surface around the submerged structures under different scouring conditions vary greatly. In order to investigate the scour mechanism, the reformed group (RNG) turbulence model in computational fluid dynamics (CFD) simulation software (v11.2) was used to simulate the scour under the clear-water scour and live-bed scour environments, and different scour morphology characteristics around the tandem piers under the clear-water scour and live-bed scour environments were obtained in the final simulation. By capturing the cross-sectional vortex and bed shear stress during the scouring process, the characteristic pattern of scouring topography around the pier and the relationship between the scour hole structure scale were analyzed, and the relationship equation between the development of scour depth and time scale was established. The study shows that: under the clear-water scouring environment, the sediment transport rate lags behind, but the contribution time is superior; under the live-bed scouring environment, by the shading and reinforcement influence of the upstream piers, the extent and development of the downstream pier surrounding the scour hole is small; the development trend of the maximum sediment transport rate of the scour hole and the great value of the shear stress is more synergistic, and the peri-pier eddy is positively correlated with the bed shear stress; through the regression equation to compare the relevant test and simulation results, the two are in good agreement, indicating that the simulated local scour evolution law is consistent with the actual law.
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Марьин, Василий, Vasily Mar'in, Александр Верещагин, Alexander Vereshchagin, Николай Бычин, and Nicolay Bychin. "Winter Buckwheat Grain: The Dynamic Pattern of the Mechanical Properties of the Main Fraction." Food Processing: Techniques and Technology 49, no. 1 (June 26, 2019): 97–103. http://dx.doi.org/10.21603/2074-9414-2019-1-97-103.
Повний текст джерелаАнотація:
As quality requirements get lower and lower, the quality of buckwheat grain meant for buckwheat groats is deteriorating. The most typical example is winter buckwheat grain. Buckwheat grain has to be sorted according to various fractions before scouring. Thus, the mechanical properties of these fractions remain a relevant field of study. The research features the dynamic pattern in the mechanical properties of the main fractions of winter buckwheat grain according to fraction before and after storage. The research subject is fractions of buckwheat sorted according to grain size before scouring. The buckwheat grain was harvested in the foothills of the Altai Territory in May 2015; it meets the necessary standards. There were twelve samples: six samples were harvested and sent for recycling (May 2015); other six samples were stored for eight months up to March 2016. The buckwheat did not pass the temperature treatment stage. The smaller fractions revealed a greater deformation before and after storage. That can lead to a higher deformation rate during scouring. Thus, the changes in the mechanical properties of winter buckwheat grain occur differently for each fraction.
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Kolahdouzan, Fereshteh, Hossein Afzalimehr, Seyed Mostafa Siadatmousavi, Asal Jourabloo, and Sajjad Ahmad. "The Effect of Pipeline Arrangement on Velocity Field and Scouring Process." Water 15, no. 7 (March 28, 2023): 1321. http://dx.doi.org/10.3390/w15071321.
Повний текст джерелаАнотація:
This experimental study investigates the effect of changes in the arrangement of horizontal pipelines on changes in the velocity pattern in three dimensions and the scouring process around these submarine pipelines. Experiments have been carried out in four cases: single pipe, two pipes with a distance of 0.5 D, two pipes with a distance of D, and three pipes with a distance of 0.5 D (D is the diameter of the pipes). The velocity upstream, downstream, and on the pipes have been measured by the Acoustic Doppler Velocimeter (ADV). The results show that a single pipe’s scouring depth in the first case is more significant than in the other cases. In the second case, the presence of the second pipe at a distance of 0.5 D from the first pipe significantly reduced the scour depth (28.6%) compared to the single pipe condition by changing the velocity pattern around the pipelines. By increasing the number of pipes to 3 with a distance of 0.5 D, this reduction in scouring depth has reached 47.6% compared to the single pipe condition. However, in the case of two pipes with a distance of D, the reduction of scouring depth was 21.4% compared to the case of a single pipe, and compared to the case of two pipes with a distance of 0.5 D, it increased by 10%.
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Boroomand, Mohammad Reza, S. Ali Akbar Salehi Neyshabouri, and Kameleh Aghajanloo. "Numerical simulation of sediment transport and scouring by an offset jet." Canadian Journal of Civil Engineering 34, no. 10 (October 1, 2007): 1267–75. http://dx.doi.org/10.1139/l07-050.
Повний текст джерелаАнотація:
In this paper the offset jet entering a domain with a movable bed is simulated by the computer program FLUENT. To achieve this aim, sediment transport is numerically simulated using multiphase systems and the empirical coefficients are studied theoretically. The numerical results are verified by comparing the simulated total load with that obtained using existing formulae and concentration profiles from available measured data. In the final step, the offset jet scouring pattern is modeled qualitatively.Key words: offset jet, numerical simulation, FLUENT, multiphase system, turbulence, sediment, scouring.
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Wisafri. "Gerusan Lokal yang Terjadi di Hilir Bendung dan Upaya Pengendaliannya." Jurnal Ilmiah Poli Rekayasa 9, no. 2 (April 15, 2014): 74. http://dx.doi.org/10.30630/jipr.9.2.74.
Повний текст джерелаАнотація:
Majarity of damages on the dam construction in Indonesia is caused by continuous local scouring at the end side of the dam construction. It grows and reach its lower/bottorm part. It could results in degradation in the dam operation safety. This local scouring was caused by major water flowing passing the dam where there is a high difference level between the top and the end of the dam. Furthermore, it generates inbalancing water flow speed and additional water turbulence. There are different approachs to prevent such damage, and for example by providing one or more additional construction at the end part of the dam. This structure is designed and installed at the bottom part of the dam. Various empirical functions have been developed to design this structure, and one of them is developed by Lacey. The function is reprsented by D = 0.47 * (Q/F)1/2 (D= scouring depth, Q= Discharge, F= the size of the sand particle). However, that function has some limitation. For examples are the local river and dam construction characteristics. Therefore, it is required to be validated by developing a model of dam contructed in a laboratory. Experiments was undertaken by using the model with different characteristics of water flow in order to investigate the scouring pattern, and than method prefentif work
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Hassanzadeh, Yousef, Milad Khosravi, and Nazila Kardan. "Numerical investigation on the effect of bluntness factor on scouring mechanism by using lenticular geometry piers." Canadian Journal of Civil Engineering 47, no. 3 (March 2020): 279–90. http://dx.doi.org/10.1139/cjce-2017-0658.
Повний текст джерелаАнотація:
Local scour and flow field around cylinders with lenticular geometry and different bluntness factors under the clear-water state were investigated numerically. To examine the scouring, large eddy simulation with a WMLES-Omega sub-grid model incorporating the sediment transport and morphodynamic model was applied. Streamlined geometry of the pier significantly affected the scour pattern and flow field in the lenticular model with length to width ratio of 5 and bluntness factor of zero. In the mentioned case, a very small scoured region was estimated at the sides of the pier, so it can be concluded that scour depth and scoured region decreases as the length to width ratio increases. Investigation of the scouring process and the flow field revealed that, the flow separation can affect the scour mechanism more in comparison to down-flow.
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Vigdorowitsch, Michael, Valery V. Ostrikov, Alexander N. Pchelintsev, and Irina Yu Pchelintseva. "Diffusion Kinetics Theory of Removal of Assemblies’ Surface Deposits with Flushing Oil." Computation 11, no. 8 (August 20, 2023): 164. http://dx.doi.org/10.3390/computation11080164.
Повний текст джерелаАнотація:
The diffusion kinetics theory of cleaning assemblies such as combustion engines with flushing oil has been introduced. Evolution of tar deposits on the engine surfaces and in the lube system has been described through the erosion dynamics. The time-dependent concentration pattern related to hydrodynamic (sub)layers around the tar deposit has been uncovered. Nonlinear equations explaining the experimentally observed dependences for scouring the contaminants off with the oil have been derived and indicate the power law in time. For reference purposes, a similar analysis based on formal chemical kinetics has been accomplished. Factors and scouring parameters for the favor of either mechanism have been discussed. Any preference for either diffusion or chemical kinetics should be based on a careful selection of washing agents in the flushing oil. Future directions of studies are proposed.
Дисертації з теми "SCOURING PATTERN"
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Johnson, Michael Farley. "Cactus Hill, Rubis-Pearsall and Blueberry Hill : one is an accident; two is a coincidence; three is a pattern : predicting "old dirt" in the Nottoway river valley of Southeastern Virginia, USA." Thesis, University of Exeter, 2012. http://hdl.handle.net/10871/9541.
Повний текст джерелаАнотація:
This thesis covers more than thirty years of the author's research into the Paleoamerican period of the Middle Atlantic Region of North America, including the last 19+ years of focused work on the Cactus Hill site (44SX202) and replication of the Paleoamerican occupation discovered there. Using a landform and geology based predictive model derived from the Paleoamerican occupation at Cactus Hill, the author directed preliminary archaeological testing in three other areas of the same Nottoway River Valley, where Cactus Hill is located. These areas were the Barr site, located 11 miles (18 km.) downriver from Cactus Hill; the Chub Sandhill Natural Resource Conservation Area, located 19 miles (30 km.) downriver from Cactus Hill; and the Blueberry Hill site (44SX327), located approximately 1,000 feet (300 meters) east of Cactus Hill. The latter two produced OSL dated, pre-Younger-Dryas landforms, as predicted. The Rubis-Pearsall site (44SX360), located in the Chub Sandhill preserve also produced a buried Paleoamerican, Clovis age cultural level confirming the model. In addition to the OSL dates, Blueberry Hill also produced a distinct and apparently discrete activity surface with a possible pre-Clovis age Cactus Hill point at the same depth as the Paleoamerican levels at Cactus Hill and Rubis-Pearsall.
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Brun, Soren Erik. "Sequential scouring, alternating patterns of erosion and deposition, laboratory experiments and mathematical modelling." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0001/NQ35117.pdf.
Повний текст джерела
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Chou, Chun-Heng, and 周君衡. "A Study on Stone Sill Pattern Subjected to River Flow Scouring." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/39566357947070375691.
Повний текст джерелаАнотація:
碩士中國文化大學
建築及都市計畫研究所
99
Taiwan have high and precipitous landform with plentiful rainfall, a high speed flow stream easily to cause a riverbed scrub and destroy structures, so to dredge stream become the most important work of preparedness against natural disaster. Stone sill is the most common protection river bed scouring structures on the transverse direction of rivers, due to some principles of easy to get material and tally with ecological landscape, material naturalized and the economically construction, only the analysis theory of stone sill entirety permutation in stability still need to be developed. In this study, we use the DDA (Discontinuous Deformation Analysis) method to build an analysis model, so that can understand the different permutation style of stone sill to the influenced of riverbeds’ stability. First, this study will review the solid-bed hydraulic engineering analysis and alignment model of abroad and internal wild stream, to be a mold of selection the stone size, permutation pattern, and as the main simulation object of the usually stream, to consider for two riverbed’s width of 6m and 10m, Use the three permutation methods: 8 word-type array, parabolic and uniform arrangement, even particle permutation in different rise-span ratio (1 / 3, 1 / 4, 1 / 6, 1 / 8) permutations and combinations, application DDA to find out the most suitable permutation under a different flow speed mode. The analysis result of this study showed differences in the proportion of rise-span ratio can significantly influence the stability, of the mode in every permutation shows the average displacement of 1/8 rise-span ratio will increase 390% ~ 726% than the 1/3 rise-span ratio. And in the different three permutation models, the 8 word-type array can sustain higher flow speed attack than other two models.
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KUMAR, BHARAT. "SCOURING PATTERN AT DOWNSTREAM OF DIFFERENT TYPES OF ENERGY DISSIPATORS ON FLAT BED AND INCLINED BED USING TWO DIFFERENT SIZE OF AGGREGATE." Thesis, 2016. http://dspace.dtu.ac.in:8080/jspui/handle/repository/15313.
Повний текст джерелаАнотація:
Dams and barrages play a very vital role in the economy of a country by providing essential benefits like irrigation, hydropower, flood control, drinking water, recreation, etc. However, when these fail in rare conditions, these may cause catastrophic flooding in the downstream area resulting in huge loss to human life and property. The spillway is among the most important structures of a dam project. It provides the project with the ability to release excess or flood water in a controlled or uncontrolled manner to downstream to ensure the safety of the project. The surface of the spillway should also be such that it is able to withstand erosion or scouring due to the very high velocities generated during the passage of a flood through the spillway. So the safety of spillway against the scouring at downstream is also important. To prevent the scouring of the riverbed and failure of the hydraulic structure, energy dissipators are commonly used for the purpose of dissipating the excessive kinetic energy of flowing water downstream of hydraulic structures.
An experimental study was conducted to understand the scouring pattern below downstream of the spillway. A rectangular flume of dimensions 6.0m(length)X0.30m(width)X0.60m(depth), four spillway models(ogee spillway, ski jump bucket, ogee spillway with subsidiary dam, ogee spillway with baffle wall) and locally available material to prepare bed were used in this study. A pitot tube was used to measure the flow velocity and discharge. To measure the pre-jump and post-jump for the calculation of energy loss point gauge was used. In this experimental study total 40 tests were conducted using same run time. The scour pattern (depth and length) were measured after each test run.
Книги з теми "SCOURING PATTERN"
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Brun, Søreb Erik. Sequential scouring: Alternating patterns of erosion and deposition-laboratory experiments and mathematical modelling. 1998.
Знайти повний текст джерелаЧастини книг з теми "SCOURING PATTERN"
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Alemi, Mahdi, João Pedro Pêgo, and Rodrigo Maia. "Numerical Modeling of Bridge Piers Scouring Flow Patterns." In Computational and Experimental Simulations in Engineering, 229–36. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-27053-7_22.
Повний текст джерела
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Sorourian, S., A. Keshavarzi, B. Samali, and J. Ball. "Study of blockage effect on scouring pattern downstream of a box culvert." In From Materials to Structures: Advancement through Innovation, 741–44. CRC Press, 2012. http://dx.doi.org/10.1201/b15320-131.
Повний текст джерела
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Boose, Emery R. "Hurricane Impacts in New England and Puerto Rico." In Climate Variability and Ecosystem Response in Long-Term Ecological Research Sites. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195150599.003.0008.
Повний текст джерелаАнотація:
Hurricanes have a profound effect on many coastal ecosystems. Direct impacts often include wind damage to trees, scouring and flooding of river channels, and salt-water inundation along shorelines (Simpson and Riehl 1981; Diaz and Pulwarty 1997). In some areas, secondary impacts may include landslides triggered by heavy rains (Scatena and Larson 1991) or catastrophic dry-season fires resulting from heavy fuel loading (Whigham in press). This chapter will focus on the longterm impacts of hurricane wind damage at two LTER sites, the Harvard Forest (HFR) in central New England and the Luquillo Experimental Forest (LUQ) in northeastern Puerto Rico. These two sites, both located in the North Atlantic hurricane basin and occasionally subject to the same storms, provide interesting examples of tropical and temperate hurricane disturbance regimes. Wind damage from a single hurricane is often highly variable (Foster 1988). Damage to individual trees can range from loss of leaves and fine branches, which can significantly alter surface nutrient inputs (Lodge et al. 1991), to bole snapping or uprooting, which can significantly alter coarse woody debris and soil microtopography (Carlton and Bazzaz 1998a and b). At the stand level, damage can range from defoliation to individual tree gaps to extensive blowdowns, creating different pathways for regeneration (Lugo 2000). At landscape and regional levels, complex patterns of damage are created by the interaction of meteorological, topographic, and biological factors (Boose et al. 1994). Adding to this spatial complexity is the fact that successive hurricanes are not necessarily independent in terms of their effects. A single storm lasting several hours may have effects that persist for decades (Foster et al. 1998). And forest susceptibility to wind damage is strongly influenced by composition and structure, which in turn are strongly influenced by previous disturbance history (Foster and Boose 1992). Thus, the impacts of a single hurricane may depend in part on the impacts of earlier storms as well as on other previous disturbances and land use. Hurricanes, like other disturbances, both create and respond to spatial heterogeneity (Turner et al. 2003). To understand the long-term ecological role of hurricanes at a given site, we must consider these three sets of questions: (1) What is the hurricane disturbance regime?
Тези доповідей конференцій з теми "SCOURING PATTERN"
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Evgin, E., and Z. Fu. "Numerical Analysis of Soil Response to Ice Scouring." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57293.
Повний текст джерелаАнотація:
Icebergs and ice ridges frequently scour the surface of seabed deposits. Ice scouring can be problematic for offshore pipelines and other seabed installations. In order to reduce the risk of failure, pipelines are buried in the seabed. However, a stationary or moving ice feature could cause a significant increase in stresses and deformation in the seabed soil deposits below the contact surface between the soil and the ice, and consequently, might result in structural failure of buried pipeline. Safe burial depth for pipelines has been the subject of both experimental and numerical studies. In this paper, two and three dimensional analyses are conducted using PLAXIS and ADINA. In these analyses, geometric and material nonlinearities are considered. In order to establish the validity of the finite element calculations, the experimental results reported in the literature and the numerical results obtained in the present study are compared. The emphasis is placed on determining the importance of (1) using interface elements between different materials such as soil and ice, soil and pipelines; (2) using the soil model correctly, and (3) using a three dimensional analysis rather than a two dimensional analysis. The changes taking placed in the deformation pattern and the stress states in the seabed soils resulting from ice scouring are determined. The effects of pipeline burial depth, the shape of the ice feature, and the characteristics of seabed soils on the stresses acting on the pipeline are evaluated.
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Givi, M. Hamed Besharati, Mohammad Saeid Madihi, and Habib Hakimzadeh. "Numerical Investigation of the Effect of a Pier’s Shape on the Mitigation of Scouring." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49448.
Повний текст джерелаАнотація:
Nowadays, scouring has become an important issue in coastal engineering. Exposed to a flow, piers of different structures will continually be in danger of scouring. Thus, design of cross-sections for piers in order to produce the least turbulence in the flow passing the pier is a significant concern from hydrodynamical and structural points of view, in so far as the status quo studies concerning optimum pier cross-sections have engaged a major portion of civil engineering researches. In this study, a comparison has been made between the flat-bed scouring pattern in the vicinity of cylindrical and conical piers by investigating the flow pattern around them. Thus, 3D numerical models of flow around a cylindrical pier and conical piers with a same bed diameter as the cylindrical pier and ratios of diameter in the water surface to bed diameters of 0.75, 0.5, 0.375 and 0.25 has been developed, with the models being meshed in GAMBIT and analyzed in FLUENT. The 3D numerical model results of flow pattern around the cylindrical pier were then compared to the experimental data available. These results and data have been used to verify the results of the 3D numerical models of the present study. Consequently, the 3D numerical models of the flow around four conical piers with different slopes have been analyzed and achieved using the FLUENT software, in which specifications of the channel, flow and the software parameters have been set to be same in all models.
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Pourahmadi, Masoumeh, and Habib Hakimzadeh. "Experimental Investigation of Local Scour Around Conical Pier." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49474.
Повний текст джерелаАнотація:
There are many reports about failure of bridges around the world due to scouring. This shows the importance of research on scouring and any possibility on scour protection. The method used of control of scouring around the bridge piers can be divided in two categories, namely: Direct and Indirect methods. The first method may be done by increasing the streambed resistance. This is usually done by riprap around piers. Indirect control, however, can be achieved by changing the flow pattern around a pier. The second method can be done for instance by using a collar around the pier or using a slot within the pier. Another method of the second category is to use variable section in depth. For this purpose, various slopes of conical piers are investigated in this research study. Experiments were carried out in a channel with 10 meters long, 0.3 meter wide and 0.5 meter depth, having a horizontal slope. Median size of sediment was 0.78 mm with geometric standard deviation of 1.24. The experimental results have been shown that the scour depth at conical piers decrease in compare with cylindrical ones. These observations, may partly be due to decrease in bed shear stress, which is a key parameter for the sediment transport. Therefore, from experimental data it was found that with a very mild slope on conical pier, the scour depth decreased about 15.8% when compared with the cylindrical one. For the other piers with larger slope and larger diameter on the bed, the wall side effects were appeared, however the reduction rate of scour depth was not as much as expected, compared with the first conical pier.
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Afzal, Mohammad Saud, Hans Bihs, Arun Kamath, and Øivind A. Arntsen. "Three Dimensional Numerical Modelling of Pier Scour Under Current and Waves Using Level Set Method." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23478.
Повний текст джерелаАнотація:
Stability of offshore structures can be threatened by local scouring which could ultimately lead to their failure. As a consequence, knowledge of the scouring mechanism and the accurate prediction of the characteristic scour geometry is very important for the design of such structures. A three-dimensional computational fluid dynamics model is used to calculate the scour and the deposition pattern around a pier for two different boundary conditions: constant discharge and regular waves. The computational fluid dynamics (CFD) model solves Reynolds-Averaged Navier-Stokes (RANS) equations in all three dimensions. The location of the free surface is represented using the level set method, which calculates the complex motion of the free surface in a very realistic manner. For the implementation of waves, the CFD code is used as a numerical wave tank. For the geometric representation of the moveable sediment bed, the level set method is used. The numerical results for the local scour prediction are compared with physical experiments. The performance of the turbulence models, the formulations of the critical shear stress for the sloping bed and the effect of the variation of the sediment time stepping are investigated. The decoupling of the hydrodynamic and the morphodynamic time step is tested and found to be a reasonable assumption. For the two situations of local pier scour under current and wave conditions, the numerical model predicts the general evolution (geometry, location and maximum scour depth) and time development of the scour hole accurately.
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Abbas, Amjed, Muhannad Abbas, Ibrahim Al-Ani, and Havan Salman. "Investigating the Effect of Different Roughness on Velocity Pattern at a Reach of Shatt-Al-Arab." In INTERNATIONAL CONFERENCE ON ARCHITECTURAL AND CIVIL ENGINEERING 2020. Cihan University-Erbil, 2021. http://dx.doi.org/10.24086/aces2020/paper.321.
Повний текст джерелаАнотація:
Shatt al-Arab River is the only international navigational river in Iraq, extending from the city of Qurna to its mouth in the Arabian Gulf at the city of Al-Fao within the governorate of Basrah for a length of approximately 204 km. Its width ranges from 400 m to 2000 m and its depth ranges from 8 m to 20 m. Since many years Shatt al-Arab River suffer from scouring at the right side (Iraqi side), that is led to displace the borders between Iraq and Iran (Al- Thalweg Line) towards Iraqi territory and thus led to loss of Iraqi land to Iran. Reducing flow velocity along the Iraqi side can led to reducing or preventing erosion in the right bank. Increasing the riverbed roughness will reduce the velocity of flow and then reducing the erosion. This principle was adopted in this study. In this research, a reach of Shatt Al-Arab with a length of 2.5 km located at 34 km northern Fao city was selected to represent the study area. A small area at the upstream of the reach mentioned earlier (700 m length) was selected and called strip in order to change the bed roughness for three different heights. This scenario was simulated with full scale (prototype scale) to investigate the effect of increasing the bed roughness on the velocity pattern at river cross sections and along the reach. The simulation done by using 3D numerical modeling CFD solver (ANSYS fluent 19). For each allocated area, as increasing the roughness height (ks), the longitudinal velocity (v) decreased at the right side by about 10% to 70% and increased by about 5% to 260% at left side along the river reach.
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Solomon, Steven M., Donald F. Forbes, Paul Fraser, Brian Moorman, Christopher W. Stevens, and Dustin Whalen. "Nearshore Geohazards in the Southern Beaufort Sea, Canada." In 2008 7th International Pipeline Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ipc2008-64349.
Повний текст джерелаАнотація:
Proposed development of a gas pipeline southward from the Mackenzie Delta and the presence of known accumulations of gas and oil in the southern Beaufort Sea suggest that construction of pipelines and associated infrastructure in the nearshore are likely to be proposed in the future. Recent surveys undertaken by Natural Resources Canada and its partners have focused on the shallow, poorly mapped nearshore region of the Mackenzie Delta (<6 m water depth) that extends ∼50 km offshore and lies largely within the landfast ice zone. Ice-keel scouring, strudel scour and nearsurface ice-bonding are being investigated. High resolution sidescan sonar and multibeam bathymetry systems were used to map the seabed over three consecutive years and show that ice keel scouring of the seabed is extensive. The maximum scour depth measured was 0.6 m in 6 m water depth with an average scour depth of 0.2 m. The same scours were visible in repeat surveys indicating that sedimentation was sufficiently low during the study, so that the scours were not infilled. Strudel drainage and associated seabed scour occurs when spring-melt river water overflows onto the surface of the landfast and bottomfast ice once discharge exceeds under-ice channel capacity, then drains back through the floating landfast ice via cracks and holes. Although common offshore of small deltas on the Alaska and Yukon coast, these features were first documented in the Mackenzie Delta area during field surveys in 2006 and 2007 that revealed strudel drainage (radial drainage patterns) features on the ice surface. A total of three strudel scours were later identified using swath-survey equipment in 1.2 m of water. The largest scour was 20 m wide with a maximum depth of 0.8 m below the surrounding seabed. Extensive surveys in Alaska have identified strudel scours exceeding 3 m below the seabed. Nearsurface ice-bonding and permafrost are known to occur in shallow water where sea ice freezes to the seabed. A combination of Synthetic Aperture Radar (SAR), ground penetrating radar (GPR) and multi-year ground temperature measurements have been used to map the horizontal and vertical extent of nearsurface ice bonding in extensive shoals found off the front of the Mackenzie Delta. In the shallowest water depths permafrost extends to 22 m below the seabed with an active layer of less than 1.2 m. In deeper water, permafrost disappears but seasonal frost can form in the upper 2–3 m of the seabed.