476 results on '"wave action"'
Search Results
2. Wave Methods for Oil Extraction Enhancing: Theoretical Support, Safety Issues, and Prospects
- Author
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Denysiuk, Ivan, Skurativska, Inna, Hubar, Ihor, Saliuk-Kravchenko, Oleksandr, Taraduda, Dmytro, Kacprzyk, Janusz, Series Editor, Novikov, Dmitry A., Editorial Board Member, Shi, Peng, Editorial Board Member, Cao, Jinde, Editorial Board Member, Polycarpou, Marios, Editorial Board Member, Pedrycz, Witold, Editorial Board Member, Babak, Vitalii, editor, and Zaporozhets, Artur, editor
- Published
- 2024
- Full Text
- View/download PDF
3. Particle transport by two-phase filtration flow from a porous medium under wave action
- Author
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A. I. Nikiforov and R. V. Sadovnikov
- Subjects
wave action ,porous medium ,two-phase filtration ,control volume method ,Geology ,QE1-996.5 - Abstract
The paper discusses the influence of wave action on the process of detachment and transport of particles from a porous body by a two-phase filtration flow. When modeling this process, the problem of the influence of the wave field on the force under the action of which the particles are detached from the pore walls is solved. For the first time, a pore-size distribution function is used for its solution. An expression for the critical flow velocity under wave action has been obtained. Critical frequency value of wave action depends on the capillary radius and the smaller the capillary radius is, the higher frequency is needed to enhance the effect of the action. At higher frequency of oscillation the peak of maximum change in the thickness of the sedimentary layer is shifted towards the pores of small radius. To maintain the influence of the wave field on the filtration parameters of the porous medium, the wave action should be carried out at a dynamically changing frequency range to increase the coverage of the effect of as many pores as possible. It is shown that particle transport during wave action increases due to the action of inertial forces, which reduce the influence of forces holding the particles on the pore surface.
- Published
- 2024
- Full Text
- View/download PDF
4. Dynamics of Hydrodynamic Pressure in the Well with Packer Sucker-Rod Well Pumps.
- Author
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Svalov, A. V.
- Subjects
- *
OIL well pumps , *RESERVOIR rocks , *ROCK permeability - Abstract
A study is made of the possibility of using sucker-rod well pumps for oil withdrawal from the below-packer space of a producing well as a method of continuous excitation of fluctuations of hydrodynamic pressure in the wellbore for wave action on the face zone of this well. The action of pulses of hydrodynamic pressure on the pay formation in the nearwellbore zone contributes to the cleaning of microparticles clogging the rock′s void space from it, to the development of a crack system in the rock, to the reduction in the efficient viscosity of formation fluids possessing viscoplastic properties, etc. This action tends to raise the efficiency of producing wells. By mathematical-modeling methods, the author has obtained an analytical expression describing, with a high degree of accuracy, the dynamics of hydrodynamic pressure in the wellbore over one period of operation of suckerrod well pumps. It has been shown that in high-permeability formations with a formation-fluid viscosity close to the viscosity of water, the amplitude of hydrodynamic-pressure fluctuations in the below-packer zone of the wellbore is relatively small and is measured by values of the order of hundredth fractions of an MPa. On reduction in the permeability of reservoir rock, rise in the viscosity of the formation fluid, and growth in the well yield, the amplitude of pressure fluctuations grows up to ~1 MPa or more, which is responsible for the high efficiency of wave action on face zones. The obtained results may be used to assess the efficiency of use of sucker-rod well pumps in combination with packers to stimulate filtration processes in the face zones of oil-producing wells. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Tidal Flat Erosion Processes and Their Dynamic Mechanisms on the South Side of Sheyang River Estuary, Jiangsu Province.
- Author
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Zhang, Wangze, Ouyang, Kai, Zhang, Xiaofei, Wang, Aijun, Yu, Qian, Ye, Xiang, and Yao, Caihua
- Subjects
TIDAL flats ,EROSION ,COASTAL changes ,TIDAL currents ,ESTUARIES ,SUSPENDED sediments - Abstract
Tidal flats are accumulations of fine-grained sediment formed under the action of tides and play a very important role in coastal protection. The northern part of Jiangsu coast, as a typical example of muddy coasts found all over the world, has experienced serious erosion since the Yellow River shifted northward, and the range of erosion has been gradually extending southward, now reaching the south of the Sheyang River estuary (SYRE). In order to address coastal erosion near the SYRE through protective measures, there is an urgent need for research on the spatial and temporal variation of coastal erosion processes and their control mechanisms in the SYRE and adjacent coastal areas. For this study, the tidal flats on the south side of the SYRE were selected as the study area, and the sediment dynamics in the upper and lower intertidal flat were observed in different seasons to investigate the erosion processes and their dynamic mechanisms. The results show that the tidal current and wave action in the observed intertidal flats are stronger in winter than in summer, and these intertidal flats erode under the combined action of waves and currents. During winter, the net transport of the near-bottom suspended sediment and bedload is primarily towards the southeast, while in summer, the direction tends toward the north and northeast. The net transport fluxes are larger in the lower part of the intertidal flat than in the upper part in summer and also larger in winter than in summer within the lower intertidal flat. Furthermore, the tidal flat erosion in the study area manifests as shoreline retreat and flat surface erosion. The average shoreline retreat rate increased from 23.3 m/a during 2014–2019 to 43.5 m/a during 2019–2021, and the average erosion depth of the lower and upper parts of the intertidal flat over a tidal cycle is, respectively, 1.98 cm and 0.24 cm in winter and 1.65 cm and 0.26 cm in summer. The ratio of the wave-induced bottom shear stress to the tidal current-induced bottom shear stress is 0.40~0.46 in the lower intertidal flat and increases to 0.66~0.67 in the upper intertidal flat, indicating that the intertidal flat erosion in the study area is primarily driven by tidal currents, with significant contributions from wave action, especially in the upper intertidal flat. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. Behavior Analysis of a Bucket Foundation with an Offshore Wind Turbine during the In-Water Sinking Process.
- Author
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Ye, Fangdi, Lian, Jijian, Xiao, Tianrun, Xiong, Dongzhi, Wang, Haijun, Guo, Yaohua, and Shao, Nan
- Subjects
BEHAVIORAL assessment ,WIND turbines ,WIND power ,OCEAN waves ,PAILS ,OCEAN bottom - Abstract
To enhance the safety of the in-water sinking operation for an integrated system, including a bucket foundation (BF), tower, and rotor nacelle assembly (RNA), in complex marine environmental conditions, a model test of in-water sinking for an offshore wind turbine and bucket foundation (OWT–BF) is conducted. The motion behavior of the OWT–BF and the sling tensions during the in-water sinking process are investigated, and the numerical method is validated through test results. The results demonstrate a positive correlation between the wave height and motion response of the OWT–BF. The most critical stage of the in-water sinking operation occurs when the top cover of the bucket is fully submerged, resulting from the substantial cross-sectional difference between the bucket base and the transition section. Furthermore, the closer the OWT–BF is to the seabed, the less it is affected by waves in terms of motion response. It is advisable to conduct the in-water sinking operation of the OWT–BF in sea states with wave heights below 1.5 m. Simultaneously, slings can efficiently control the motion response of the OWT–BF, thereby enhancing the safety of the sinking operation. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
7. INFLUENCE OF RELAXATION ON FILTERING MICROFLOWS UNDER HARMONIC ACTION ON THE LAYER.
- Author
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Denysiuk, I. I., Skurativska, I. A., Bielinskyi, I. V., Syzonenko, O. M., and Hubar, I. M.
- Subjects
SEPARATION of variables ,BOUNDARY value problems ,DIFFERENTIAL equations ,DARCY'S law ,BOUNDARY layer (Aerodynamics) ,CONIC sections - Abstract
Purpose. Investigation of the velocity fields of non-equilibrium fluid filtration in a layer under harmonic action on it and assessment of the influence of relaxation effects on the attenuation of the amplitude of initial disturbances within the framework of mathematical modeling of non-equilibrium plane-radial filtration. Methodology. A mathematical model of non-equilibrium plane-radial filtration with a generalized dynamic Darcy law in the form of a boundary value problem in a half-space with a harmonic excitation law at its boundary is considered. Based on the exact solutions of the boundary value problem, the attenuation of the amplitude of initial disturbances under the model’s parameters varying and influence of parameters on the size of the disturbed region are investigated. Findings. A differential equation modeling non-equilibrium filtration processes in the massif in the cylindrical reference frame was obtained. Using the method of separation of variables, a solution was constructed, bounded at infinity, to the model differential equation subjected to harmonic action at the layer boundary. The solution’s asymptotic approximation was constructed for large values of the argument. Using the asymptotic solution of the boundary value problem, the damping of velocity field during non-equilibrium filtration was analyzed depending on the frequency of the harmonic action, the ratio of the piezoconductivity coefficients of the layer, and the relaxation time. Profiles of the dependences of the size of the influence zone on the model parameters were plotted and the choice of parameters for optimal influence on the bottom-hole zone of the well was analyzed. Originality. On the basis of the non-equilibrium filtration model, it is shown that harmonic disturbances applied to the boundary of a semi-infinite layer can penetrate the reservoir over a greater distance under the conditions of manifestation of the relaxation mechanism of the fluid-skeleton interaction, compared to the equilibrium filtration process. Such an effect is observed at a finite interval of disturbance frequencies, while at high frequencies relaxation contributes to a more significant damping of disturbances. In the parametric space of excitation frequency – relaxation time, there is a locus of points that corresponds to the maximum size of influence zone of disturbances. Practical value. The obtained results are relevant for research on the impact of wave disturbances on the layer with the aim of intensifying filtration processes, as well as for creation of new wave technologies to increase the extraction of mineral resources from productive layers. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
8. Seasonal bleaching and partial mortality of Pocillopora verrucosa corals of the coast of central Vietnam.
- Author
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Lishchenko, Fedor V., Burmistrova, Yuliya A., Petrochenko, Roman A., Nguyen, Thanh H., and Britayev, Temir A.
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CORAL bleaching ,CORAL colonies ,ENVIRONMENTAL impact analysis ,CORALS ,CORAL communities ,CORAL reefs & islands - Abstract
Introduction: Coral reefs are one of themost productive yet vulnerable ecosystems on Earth. An important step in understanding the functioning of coral communities is studying the environmental impact on the state of reefs. The present study aimed to assess the impacts of the water temperature, precipitation, wave action, and population density on the seasonal bleaching, partial and complete mortality of shallow-water branching corals of Pocillopora verrucosa species complex. Materials and methods: The present study was conducted at the Dam Bay research station (Nha Trang Bay) from 26 April 2020 to 2 April 2021. The environmental data was collected from the Dam Bay weather station and using a temperature logger planted on the nursery, coral bleaching and mortality were assessed visually using photos taken underwater. Results: Throughout the study, the percentage of bleached coral colonies varied from 1 to 41.5% with two peaks, in autumn (October) and spring (April). Rates of the development of partial mortality varied from 0 to 10%, with a pronounced peak in December. At the end of the experiment, the percentage of coral colonies suffering from partial mortality reached 47%. Only 4,5% of experimental colonies died to the end of the study. Analysis revealed that water temperature and partial mortality are the drivers of bleaching, while wave action, temperature and bleaching are the factors with a significant impact on partial mortality. Discussion: Thus, both bleaching and patrial mortality are interlinked and the effect of partialmortality on bleaching is stronger than the opposite. Both phenomena have pronounced seasonal variation, but theirmaximummanifestation does not coincide in time allowing corals to avoid their synergetic effect. Moreover, it was found that the impact of individual stress on mortality prevailed over the impact of seasonal bleaching and partial mortality events. The main cause of coral death was the development of algal fouling at the sites of colony lesions, which gradually spread over the entire surface of the colony. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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- View/download PDF
9. 北戴河西海滩波浪动力与人工养护沙滩侵蚀 原位监测研究.
- Author
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冯梅, 冀坷帆, 白玉川, 王刚, 张甲波, and 黄哲
- Subjects
- *
EROSION , *BEACHES - Abstract
This paper measured the evolution and wave data of the nourished beach, estimated the contributions of erosion amount and effective wave height to beach erosion by taking the West Beach of Beidaihe as an example. The results show that the beach has an overall erosion trend after the nourishment, with the maximum erosion height of 1.7 m. The cumulative influence of the wave height on the beach erosion is an exponential distribution. Although large waves with lower recurrence frequencies (significant wave height>0.6 m) can cause greater beach erosion, their cumulative contribution to the total beach erosion is only about 25%, while the contribution of regular waves with heights of 0.3 m to 0.6 m can reach 75%. This study can provide reference for maintaining the quality of artificial beach, and beach evolution prediction after artificial nourishment. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
10. Understanding Flexibility Effects in the Interaction of Light-Frame Wood Structures with Wave Action.
- Author
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Kotzamanis, Vasileios and Kalliontzis, Dimitrios
- Subjects
- *
BUILDING foundations , *FLUID-structure interaction , *LIGHTWEIGHT construction , *WAVE forces , *TSUNAMIS , *SOIL classification - Abstract
Hurricane and tsunami events can generate extreme water flows in nearshore regions of the United States with catastrophic consequences to coastal structures. Field records have shown that light-frame wood structures exhibit high vulnerability to wave-induced forces due to their light construction characteristics, which feature flexible connections and slender pile foundation systems. Previous research has studied the behavior of these structures under wave action, but most studies used rigid body modeling, which is shown in this study to be insufficient for capturing the force demand on these structures. Using a fluid-structure interaction (FSI) framework, this research investigated the structural and soil flexibility effects in the interaction between elevated light-frame wood structures and water flows. Study variables included the flexibility of timber-to-timber connections, soil type, pile embedment, wavelength, and wave amplitude. The study concluded that structural and soil responses to water flows can introduce strong coupled motions. Neglecting this coupling effect may underestimate the force demand on the light-frame wood structures by more than 40%. Accounting for both structural and soil flexibilities is necessary to accurately quantify the wave force demand of these structures. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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11. Effect of Resonance-Wave Actions on Sedimentation Stability of Starch Nanoparticle Dispersions.
- Author
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Ganiev, S. R., Kasilov, V. P., Kislogubova, O. N., Butikova, O. A., and Kochkina, N. E.
- Abstract
The influence of resonance wave effects on the sedimentation stability of potato and corn starch nanoparticle dispersions obtained by coprecipitation was studied. It has been established that the proportion of the dispersed phase of potato starch nanoparticle dispersions formed using traditional mixing remains unchanged for two days. For corn starch nanoparticle dispersions, this indicator remains at the initial level only for the first five minutes. The use of wave action at the stage of coprecipitation leads to an increase in the values of the ξ-potential of the obtained nanoparticles by 4.5 and 3.5 times for corn and potato starches, respectively. Due to this, the dispersion stability of corn starch nanoparticles increases up to two days and dispersions of potato starch nanoparticles increase up to forty days. The results presented in this article are the basis for the development of a resource-saving technology for obtaining highly stable dispersions of biopolymer nanoparticles for food, medical, pharmaceutical, and other industries. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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12. Experimental Investigation of Dynamic Response of Pile-Supported Wharf in Liquefiable Ground Under Wave Action
- Author
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BI Jianwei, SU Lei, XIE Libo, ZHANG Yu, LING Xianzhang
- Subjects
wave action ,pile-supported wharf ,dynamic response ,liquefiable ground ,model test ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Chemical engineering ,TP155-156 ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 - Abstract
Pile-supported wharf (PSW) is widely used in the deep-water port engineering construction, most of which are located in liquefiable ground. The effect of wave action on the working performance of PSW in liquefiable ground cannot be ignored, but few studies have been reported. This study performs the wave flume test of PSW in liquefiable ground considering the soil-structure-wave interaction. This test really reproduces the operating condition of PSW, and explores the internal response difference of wharf structure under wave. The influence of wave height on dynamic response of the PSW system is discussed systematically. The result shows that the acceleration and displacement of the PSW deck gradually increase first and finally remain relatively stable with the increase of wave action. The hydrodynamic pressure and deformation of each pile in pile group are obviously different, and the response variation is related to the pile position. The pore pressure of the soil layer in the free field and around the pile decreases with the increase of depth, and the existence of the pile group can reduce the pore pressure in the soil layer around the pile, and increase the acceleration of the soil layer. The effect of wave height on the soil layer decreases with the increase of depth. The above results can provide reference for the similar PSW test under wave and the support for the design and wave protection of PSW.
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- 2023
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13. Fundamentals of Optics and Plasma Physics
- Author
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Michel, Pierre, Becker, Kurt H., Series Editor, Di Meglio, Jean-Marc, Series Editor, Hassani, Sadri, Series Editor, Hjorth-Jensen, Morten, Series Editor, Munro, Bill, Series Editor, Needs, Richard, Series Editor, Rhodes, William T., Series Editor, Scott, Susan, Series Editor, Stanley, H. Eugene, Series Editor, Stutzmann, Martin, Series Editor, Wipf, Andreas, Series Editor, and Michel, Pierre
- Published
- 2023
- Full Text
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14. Review of Literature on Design of Rubble Mound Breakwaters
- Author
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Akarsh, P. K., Chaudhary, Babloo, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Nandagiri, Lakshman, editor, Narasimhan, M. C., editor, and Marathe, Shriram, editor
- Published
- 2023
- Full Text
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15. Further Loss of Intertidal Mussel Stands on the Nova Scotia Coast (Canada) after the Passage of Cyclone Lee.
- Author
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Scrosati, Ricardo A.
- Subjects
- *
MUSSELS , *CYCLONES , *BIOLOGICAL systems , *SEASHORE , *COASTS - Abstract
Intertidal mussel stands are common on temperate rocky seashores and host many small invertebrates, so they are important biodiversity reservoirs. Their integrity, however, is being increasingly affected by environmental extremes. An unusual cold snap in Nova Scotia (Canada) in February 2023 was followed by the mass disappearance of mussel stands at mid-to-high elevations in rocky intertidal habitats. The present article presents evidence of significant losses at middle intertidal elevations following the passage of cyclone Lee in September 2023, which created severe surf conditions. The increasing occurrence of successive environmental extremes might challenge the persistence of these important biological systems. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
16. 波浪作用下液化场地高桩码头动力响应试验研究.
- Author
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毕建巍, 苏雷, 解立波, 张昱, and 凌贤长
- Abstract
Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2023
- Full Text
- View/download PDF
17. Wave rotor application for micro gas turbines
- Author
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Tuechler, Stefan, Copeland, Colin, Vorraro, Giovanni, and Akehurst, Sam
- Subjects
621.406 ,CFD Modeling ,Wave Action ,Wave Rotor ,Shock Waves - Abstract
There is an increasing demand for compact, portable and endurable power sources in both the civilian and military markets. Gas turbines are a proven technology excelling at high energy and power density, reliability and flexibility. However, downscaling turbomachinery entails severe penalties in component and system efficiency as well as service life due to increased rotational speeds, greater tip clearance and larger relative roughness effects. In this thesis, an alternative to turbomachinery is proposed using on a non-axial, throughflow wave rotor turbine that combines shaft power extraction as well as fluid compression and expansion through shock and rarefaction waves within a single rotating device. The thesis is written in the alternative thesis format and is based on five academic articles that address the performance characteristics of such a pressure-exchange device. The first paper introduces the concept of a micro-wave rotor gas turbine based on a throughflow wave rotor with non-axial channel shape. The study uses a time-marching quasi-one-dimensional wave action model that is able to accurately capture the wave pattern within a wave rotor channel. The model is coupled with a steady-flow combustor model and identifies leakage and combustor pressure drop as major performance affecting parameters. The second publication addresses an experimental study centred on an innovative four-port, three-cycle micro-wave rotor. The study seeks to characterise the wave rotor and further elaborates on the challenges in exploiting wave rotor technology. In addition, reasonably high compression and expansion efficiencies are achieved. In the third paper, the results from the second paper are then used in conjunction with literature data to validate and calibrate the quasi-one-dimensional model. The fourth paper introduces a shape-optimisation study that seeks to enhance the shaft power output of the baseline wave rotor turbine. To do so, a reduced order quasi-two-dimensional transient CFD model is coupled to a hybrid algorithm. The optimisation technique trains a Kriging surrogate model with data from a genetic algorithm and alternates the search area based on global exploration and local exploitation, thus ensuring improved coverage of the design space compared to standard evolutionary algorithms. The optimisation routine results in a wave rotor candidate design that predicts a power output improvement of 80%. The numerical results indicate that the increase in shaft power stem from increased incidence losses leading to a 3% drop in pressure ratio. Finally, the fifth and final paper verifies the numerical results through an experimental campaign comparing both a baseline and an optimised rotor. The experimental results support the validity of the reduced-order CFD model to accurately predict performance trends. Implications of the camberline change on performance are discussed as well.
- Published
- 2020
18. Tidal Flat Erosion Processes and Their Dynamic Mechanisms on the South Side of Sheyang River Estuary, Jiangsu Province
- Author
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Wangze Zhang, Kai Ouyang, Xiaofei Zhang, Aijun Wang, Qian Yu, Xiang Ye, and Caihua Yao
- Subjects
tidal flat ,coastal erosion ,sediment transport ,wave action ,Sheyang River estuary ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 ,Oceanography ,GC1-1581 - Abstract
Tidal flats are accumulations of fine-grained sediment formed under the action of tides and play a very important role in coastal protection. The northern part of Jiangsu coast, as a typical example of muddy coasts found all over the world, has experienced serious erosion since the Yellow River shifted northward, and the range of erosion has been gradually extending southward, now reaching the south of the Sheyang River estuary (SYRE). In order to address coastal erosion near the SYRE through protective measures, there is an urgent need for research on the spatial and temporal variation of coastal erosion processes and their control mechanisms in the SYRE and adjacent coastal areas. For this study, the tidal flats on the south side of the SYRE were selected as the study area, and the sediment dynamics in the upper and lower intertidal flat were observed in different seasons to investigate the erosion processes and their dynamic mechanisms. The results show that the tidal current and wave action in the observed intertidal flats are stronger in winter than in summer, and these intertidal flats erode under the combined action of waves and currents. During winter, the net transport of the near-bottom suspended sediment and bedload is primarily towards the southeast, while in summer, the direction tends toward the north and northeast. The net transport fluxes are larger in the lower part of the intertidal flat than in the upper part in summer and also larger in winter than in summer within the lower intertidal flat. Furthermore, the tidal flat erosion in the study area manifests as shoreline retreat and flat surface erosion. The average shoreline retreat rate increased from 23.3 m/a during 2014–2019 to 43.5 m/a during 2019–2021, and the average erosion depth of the lower and upper parts of the intertidal flat over a tidal cycle is, respectively, 1.98 cm and 0.24 cm in winter and 1.65 cm and 0.26 cm in summer. The ratio of the wave-induced bottom shear stress to the tidal current-induced bottom shear stress is 0.40~0.46 in the lower intertidal flat and increases to 0.66~0.67 in the upper intertidal flat, indicating that the intertidal flat erosion in the study area is primarily driven by tidal currents, with significant contributions from wave action, especially in the upper intertidal flat.
- Published
- 2024
- Full Text
- View/download PDF
19. Behavior Analysis of a Bucket Foundation with an Offshore Wind Turbine during the In-Water Sinking Process
- Author
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Fangdi Ye, Jijian Lian, Tianrun Xiao, Dongzhi Xiong, Haijun Wang, Yaohua Guo, and Nan Shao
- Subjects
offshore wind power ,air-floating structure ,bucket foundation ,wave action ,in-water sinking ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 ,Oceanography ,GC1-1581 - Abstract
To enhance the safety of the in-water sinking operation for an integrated system, including a bucket foundation (BF), tower, and rotor nacelle assembly (RNA), in complex marine environmental conditions, a model test of in-water sinking for an offshore wind turbine and bucket foundation (OWT–BF) is conducted. The motion behavior of the OWT–BF and the sling tensions during the in-water sinking process are investigated, and the numerical method is validated through test results. The results demonstrate a positive correlation between the wave height and motion response of the OWT–BF. The most critical stage of the in-water sinking operation occurs when the top cover of the bucket is fully submerged, resulting from the substantial cross-sectional difference between the bucket base and the transition section. Furthermore, the closer the OWT–BF is to the seabed, the less it is affected by waves in terms of motion response. It is advisable to conduct the in-water sinking operation of the OWT–BF in sea states with wave heights below 1.5 m. Simultaneously, slings can efficiently control the motion response of the OWT–BF, thereby enhancing the safety of the sinking operation.
- Published
- 2024
- Full Text
- View/download PDF
20. ЗАГАСАННЯ ПОЛІВ ШВИДКОСТЕЙ ПІД ЧАС НЕРІВНОВАЖНОЇ ФІЛЬТРАЦІЇ В НАПІВОБМЕЖЕНОМУ СЕРЕДОВИЩІ ЗА ГАРМОНІЧНОЇ ДІЇ НА НЬОГО.
- Author
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Денисюк, І. І., Скуратівська, І. А., and Губар, І. М.
- Subjects
- *
DARCY'S law , *BOUNDARY value problems , *POROUS materials , *PROBLEM solving , *MATHEMATICAL models - Abstract
When developing methods of wave action on porous media for the purpose of intensifying filtration processes, it becomes necessary to evaluate the attenuation of filtration oscillations in porous strata under conditions of intense high-frequency disturbances. To investigate this problem, the methods of mathematical modeling of non-stationary non-equilibrium filtration and the solving of a one-dimensional linear boundary value problem in a half-space with a harmonic disturbance at its boundary are used. The non-equilibrium nature of filtration processes in reservoirs is taken into account in the dynamic law of filtration, which is a generalization of the classical Darcy's law, by including the effects of velocity and pressure relaxation. In this research, filtering equations are considered with one and two relaxation processes, which were described by exponential relaxation kernels. The exact stationary solutions of boundary value problems were calculated by using the method of separation of variables and the damping coefficients of oscillations in space were determined. Considering the reduced damping coefficients as the ratio of the “non-equilibrium” damping coefficient to the equilibrium one, the dependences of the reduced coefficients on the disturbance frequency, on the ratio of the equilibrium and frozen filtering coefficients, and on the ratio of the relaxation times (in the case of the dynamic Darcy equation with two relaxation processes) were analyzed. In particular, the existence of a frequency that provides a minimum of damping coefficients is shown, and the displacement of the minimum point of the damping coefficient towards lower frequencies with an increase in the ratio of the filtering coefficients is established. In the case of using Darcy's law with two relaxation processes, depending on the ratio of relaxation times, the curve of the reduced damping coefficient reaches asymptotic values that differ from those corresponding to Darcy's law with one relaxation process. In addition, the points of intersection of the curves corresponding to Darcy's laws with different number of relaxation processes lie on different sides of the minimum point of the curves. Such features of the curves can be useful in the verification of mathematical filtering models. The problem is solved both for a homogeneous and for a non-homogeneous porous media. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
21. 波浪作用下粉沙临底输沙特征的试验研究.
- Author
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朱 昊, 左利钦, 陆永军, 李寿千, 王茂枚, and 刘 菁
- Subjects
- *
EXTREME weather , *SUSPENDED sediments , *PERIODIC motion , *SEDIMENT transport , *WEATHER , *STORM surges , *SILT - Abstract
Under extreme weather conditions, such as storm surges or strong winds, high-intensity sand transport at the bed bottom is prone to occur, which has a profound impact on the dynamic geomorphological processes, port and waterway facilities, and ecological protection. It is of significant theoretical and practical engineering importance to conduct research on the mechanisms of sediment transport near the bottom. In this study, silt transport under wave actions was studied via wave flume sediment transport tests conducted in varying dynamic environments. A bottom sediment measurement system with a high sensor density was constructed to collect data from the fixed bed surface to the suspended sediment layer. The results showed that sand ripples on the bed surface developed under relatively weak dynamic conditions. With the increase in dynamic excitation, ripples were eroded and sheet flow occurred. The bottom layer movement of fine sediment, revealed by analyzing the sediment concentration process at different bed heights, was characterized by the silt surface lateral oscillations aligned with the periodic wave motion. The amplitude of the silt layer oscillations decreased with increasing depth and a phase lag arose. The concepts of movement number and compactness coefficient were introduced and a formula for critical sheet flow condition for a siltsand wide gradation range was established. The bottom movement mechanism of fine- grained sediment proposed in this study will form a departing point for further studies of the mechanism of sudden- onset scouring and silting. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
22. 基于物理模拟的三角洲前缘横向砂坝发育过程及 形成机理.
- Author
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王昕, 魏思源, 吕奇奇, 代榕, 呼焕, 毕宇航, 张丽雯, 梁岩, and 张建坤
- Abstract
Copyright of Acta Sedimentologica Sinica is the property of Acta Sedimentologica Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2023
- Full Text
- View/download PDF
23. Influence of Beach Erosion during Wave Action in Designed Artificial Sandy Beach Using XBeach Model: Profiles and Shoreline.
- Author
-
Zhou, Yingtao, Feng, Xi, Liu, Maoyuan, and Wang, Weiqun
- Subjects
BEACH erosion ,BEACHES ,BIOENGINEERING ,COASTS ,SHORELINES ,STORM surges - Abstract
Beach width is an important factor for tourists' comfort, and the backshore is a swash zone where sediment moves quickly. Artificial sandy beaches focus on beach width stability and evolution. This paper is based on an artificial beach project in Haikou Bay, where, in view of the existing conditions, a new type of beach profile that can protect beach berm and width without being eroded by large wave action. Numerical simulation based on XBeach model were conducted to predict the morphodynamical responses of the beach, including a diagnosis of the erosion spots under storm and normal wave events, respectively. Sediment fluxes along and across the shoreline under varied scenarios, dependent on profile width and backshore slope, were discussed. It was found that normal waves with lower heights and longer periods can induce stronger erosion than storm waves due to the landform of the inner-bay in Haikou Bay. Engineering and biological methods to reduce beach erosion during wave action were discussed. Biological methods such as green-plants-root-system can retain berm surface sediment without allowing it to be transported offshore by wave action. The design concept of this artificial beach project may inspire more beach design and protection projects in coastal zones. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
24. Method for Calculating the Pile Metal Loss under the Influence of Water-Pebble Mixture.
- Author
-
Makarov, K. N., Biryukbaev, E. K., and Yurchenko, V. E.
- Abstract
The article presents a method for calculating the erosion furrow depth and the metal loss of piles and other structures of marine hydraulic facilities under wave action containing a water-pebble mixture (pebble bombardment of piles). [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
25. Soil friction on a retaining wall under seismic load
- Author
-
Minaev Oleg
- Subjects
retaining wall ,active pressure ,soil friction ,dynamic load ,foundation ,bearing capacity ,stability ,wave action ,seismic intensity ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The paper is the first to establish that the classical quasi-static analytical calculation of the retaining wall for seismic load indirectly reflects the wave nature of the impact of the sandy backfill soil on the rear surface of a retaining wall. The evidence provided includes the comparative results of the designed gravity retaining wall made from reinforced concrete and having a front cantilever that consider and disregard soil friction under the calculated operational static and seismic loads. The calculations were carried out for given dimensions of the retaining wall and characteristics of sandy backfill soils on weak clay foundation soils. It is emphasized that the calculation results are quite consistent with the research data on the behavior of sandy soils in the plate base under dynamic wave loads. These results were used to obtain the dependence necessary for determining the angle of soil friction against the rear surface of the wall under seismic load of varying intensities. It seems quite convincing that the calculation of the retaining stack for a seismic load of 9 points can be carried out without taking into account soil friction, since in this case, under seismic action, soil slippage along the rear surface of the retaining wall is possible. With a seismic load of 7 and 8 (or less) points, the angle of friction of the soil against the rear surface of the retaining wall should be determined from the obtained dependence to determine the angle of friction of the soil under a seismic load of varying intensity given in this article.
- Published
- 2023
- Full Text
- View/download PDF
26. Ecohydrological, climatic and tree architectural considerations for reforestation program using swamp vegetation of Bangladesh.
- Author
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Sohel, Md. Shawkat Islam, Islam, H. M. Nurul, Newaz, Kazi Md. Noor, Khan, Malik Fida A., Sarker, Gopal Chandra, and Bhuiyan, Md. Sadequr Rahman
- Subjects
REFORESTATION ,SWAMPS ,FOREST dynamics ,WATER depth ,MILLETTIA pinnata ,ECOSYSTEMS ,HABITATS - Abstract
Swamp forests are now at the edge of extinction in the Haor (Haor ecosystem is a type of wetland comprised of swamp forest located in the lowlands of the north-eastern part of Bangladesh which is characterized by a bowl or saucer shaped shallow depression) region of Bangladesh. To reverse such a trend, there is an urgent need to start a reforestation program. However, the silvics of individual species and dynamics of swamp forest stands are only marginally understood. Hence, the purpose of this study was to provide detailed information on swamp vegetation water tolerance range and to identify suitable habitat range for species that are dominant in the reforestation program. It was found that high water-tolerant species can tolerate waterlogging conditions for an average of 13 weeks, followed by 07 weeks by medium water-tolerant species and 02 weeks by low water-tolerant species. In the case of species water depth tolerance, the high water-tolerant group can tolerate an average of 4ft water followed by 2.5 ft water by medium and 1ft by low water tolerant group. Hijol (Barringtonia acutangula), Koroch (Pongamia pinnata), Pitali (Trewia nudiflora) and Borun (Crataeva magna) were the dominant species used for existing small scale reforestation programs. There are no significant differences in resistance against water flow among Hijol, Koroch, Pitali and Borun regardless of vegetation density and water depth. For future large-scale plantations, the machine learning model shows that more than 50% of Haor area is suitable for plantations by these four species. The information generated through this study can be beneficial to planners and managers to aid in developing plantation plans and the design of habitat restoration and enhancement efforts. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
27. Ecofriendly improvement of coastal calcareous sandy slope using recycled shredded coconut coir (RSC) and bio-cement.
- Author
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Kou, Hai-Lei, Liu, Jia-Hui, Zhang, Peng, Wu, Chuangzhou, Ni, Pengpeng, and Wang, Dong
- Subjects
- *
COIR , *COLLUVIUM , *MICROSCOPY , *EROSION , *CALCITE - Abstract
Coconut can be found extensively in the coastal area of south China, where sandy slopes always suffer from erosion due to typhoon. Recycled shredded coconut coir (RSC) was employed in this study to increase the strength of microbial-induced calcite precipitation (MICP) treated calcareous sandy slope, whereas bio-cementation alone showed low wave resistance and high cost. A method was proposed to evaluate the erosion resistance of bio-cemented and RSC-reinforced sandy slope washed by waves. A series of model tests was used to assess and compare the erosion behaviors of calcareous sandy slopes with different treatments. Specifically, the influence of RSC content (0 and 1.2% by mass) and MICP treatment cycle (0, 2 ~ 4 cycles) was considered. Results show that the addition of RSCs could further enhance the erosion resistance of treated calcareous sandy slope and reduce the number of MICP treatment. Microscopic analysis shows that RSC can provide more attachment sites for microorganisms to promote MICP treatment, and act as a bridge to bond particles and crystals into a whole. Moreover, the penetration resistance of bio-cemented slope surface can be easily obtained by conducting penetration testing, and it shows a nonlinearly relationship with erosion resistance. Thus, an evaluation method for erosion resistance of the slope via penetration resistance was proposed in this study through fitting calculation. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
28. Further Loss of Intertidal Mussel Stands on the Nova Scotia Coast (Canada) after the Passage of Cyclone Lee
- Author
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Ricardo A. Scrosati
- Subjects
disturbance ,foundation species ,hurricane ,wave action ,Biology (General) ,QH301-705.5 - Abstract
Intertidal mussel stands are common on temperate rocky seashores and host many small invertebrates, so they are important biodiversity reservoirs. Their integrity, however, is being increasingly affected by environmental extremes. An unusual cold snap in Nova Scotia (Canada) in February 2023 was followed by the mass disappearance of mussel stands at mid-to-high elevations in rocky intertidal habitats. The present article presents evidence of significant losses at middle intertidal elevations following the passage of cyclone Lee in September 2023, which created severe surf conditions. The increasing occurrence of successive environmental extremes might challenge the persistence of these important biological systems.
- Published
- 2023
- Full Text
- View/download PDF
29. The Coupled Tube-Mooring System SFT Hydrodynamic Characteristics Under Wave Excitations
- Author
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Zou, P. X., Chen, L. Z., Chaari, Fakher, Series Editor, Haddar, Mohamed, Series Editor, Kwon, Young W., Series Editor, Gherardini, Francesco, Series Editor, Ivanov, Vitalii, Series Editor, Cavas-Martínez, Francisco, Series Editor, Trojanowska, Justyna, Series Editor, Sapountzakis, Evangelos J., editor, Banerjee, Muralimohan, editor, Biswas, Paritosh, editor, and Inan, Esin, editor
- Published
- 2021
- Full Text
- View/download PDF
30. A New Approach to Studying Delta Formation.
- Author
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Mikhailova, M. V.
- Subjects
PASSIVE components ,STORM surges ,SEA level - Abstract
The article examines delta formation processes and suggests a new approach to their study. In the paper, delta formation is divided into its active and passive component. The article assesses natural and anthropogenic external factors that impact delta formation, as well as modern trends in changing of the world's deltas. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
31. Inland Navigation Contributes to the Remobilization of Land-Based Plastics Into Riverine Systems.
- Author
-
Climo, Joshua D., Oswald, Stephanie B., Buschman, Frans A., Hendriks, A. Jan, and Collas, Frank P. L.
- Subjects
INLAND navigation ,RIPARIAN areas ,PLASTICS ,POLLUTION ,PROBABILITY theory - Abstract
Riverine systems are directly affected by plastic pollution and function as pathways for plastic transport to the sea. Plastic litter can enter the water by remobilization from the bed or from the riverbank, after which it can be transported with the flow. The process of remobilization is still poorly understood. To get a detailed understanding of the role rivers play in plastic transport and hence develop management measures to prevent or mitigate plastic transport it is vital to get a fundamental understanding of the factors contributing to remobilization of plastic on the riverbank. Therefore, we investigated how the wave action of inland navigation, one of the dominant actors in anthropogenic rivers, affects the remobilization of land-based plastics. Quantification of remobilization was performed along the riverbank of an intensely navigated river in the Netherlands (the river Waal) allowing for a real-world assessment of remobilization. Plastic pieces were placed at standardized distances from the average waterline to determine the plastic remobilization along the riverbank at different locations. Subsequently, wave actions of passing inland navigation was used to assess plastic remobilization. Inland navigation induced wave action was found to significantly cause remobilization of plastics present on the riverbank. The distance of the plastic object to the waterline combined with the wave height, riverbank slope and plastic size significantly affected remobilization probability. Overall, the remobilization effect was strongest on plastics present within ≤ 1.0 m from the waterline. With a wave height ≥ 0.5 m all plastics present up to 3.0 m from the waterline were remobilized and thereby potentially transported downstream through the river. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
32. Submergence and Wave Action Resilience of Vetiver Grass Protected Fly Ash Amended Soil Slopes.
- Author
-
Islam, Tanzila and Islam, Mohammad Shariful
- Subjects
FLY ash ,VETIVER ,ANDOSOLS ,SOIL erosion - Abstract
This study aims to investigate the durability of vegetated slopes using vetiver grass (Vetiveria zizanioides), constructed with fly ash-amended soil (FAS) against submergence and wave action in swampy areas. Four model slopes were fabricated using soil (silty sand, ϕ = 28°) of swampy area, and stabilizing the soil with 8.5% (w/w) fly ash. Slopes of two models were vegetated with vetiver, while one model had its slope protected with jute-geotextile. After 172 days of fabrication, slopes were submerged for 5 days, and then subjected to wave action of 0.2–0.3 m/s velocity. The maximum shoot and root length of vetiver varied within 130–170 cm and 61–74 cm, respectively. FAS with jute-geotextile increased the number of tillers and vegetation-covered areas subsequently by 2.0 and 2.4 times. Vetiver increased the slope durability 15 times longer with 19% less soil loss than that of the bare slope model. Resilience of the model fabricated with FAS and protected by vetiver enhanced the duration by 2 times through minimizing soil erosion by 12%. However, for the model fabricated with FAS and protected with vetiver and jute-geotextile, the duration was amplified by 3 times with 60% less soil loss than that of the vetiver protected slope. Vetiver enhanced the slope resilience to wave action and submergence. However, vetiver grass along with fly ash and jute-geotextile enhances the resilience of slope to wave action and submergence by improving soil strength, nutrient, microscopic properties; and by reducing permeability, seepage, soil erosion, forming a compatible protection system. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
33. Inland Navigation Contributes to the Remobilization of Land-Based Plastics Into Riverine Systems
- Author
-
Joshua D. Climo, Stephanie B. Oswald, Frans A. Buschman, A. Jan Hendriks, and Frank P. L. Collas
- Subjects
groyne field ,shipping ,pollution ,wave action ,meso- and macroplastic ,Environmental technology. Sanitary engineering ,TD1-1066 - Abstract
Riverine systems are directly affected by plastic pollution and function as pathways for plastic transport to the sea. Plastic litter can enter the water by remobilization from the bed or from the riverbank, after which it can be transported with the flow. The process of remobilization is still poorly understood. To get a detailed understanding of the role rivers play in plastic transport and hence develop management measures to prevent or mitigate plastic transport it is vital to get a fundamental understanding of the factors contributing to remobilization of plastic on the riverbank. Therefore, we investigated how the wave action of inland navigation, one of the dominant actors in anthropogenic rivers, affects the remobilization of land-based plastics. Quantification of remobilization was performed along the riverbank of an intensely navigated river in the Netherlands (the river Waal) allowing for a real-world assessment of remobilization. Plastic pieces were placed at standardized distances from the average waterline to determine the plastic remobilization along the riverbank at different locations. Subsequently, wave actions of passing inland navigation was used to assess plastic remobilization. Inland navigation induced wave action was found to significantly cause remobilization of plastics present on the riverbank. The distance of the plastic object to the waterline combined with the wave height, riverbank slope and plastic size significantly affected remobilization probability. Overall, the remobilization effect was strongest on plastics present within ≤ 1.0 m from the waterline. With a wave height ≥ 0.5 m all plastics present up to 3.0 m from the waterline were remobilized and thereby potentially transported downstream through the river.
- Published
- 2022
- Full Text
- View/download PDF
34. Influence of Beach Erosion during Wave Action in Designed Artificial Sandy Beach Using XBeach Model: Profiles and Shoreline
- Author
-
Yingtao Zhou, Xi Feng, Maoyuan Liu, and Weiqun Wang
- Subjects
artificial beach ,erosion ,wave action ,numerical simulation ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 ,Oceanography ,GC1-1581 - Abstract
Beach width is an important factor for tourists’ comfort, and the backshore is a swash zone where sediment moves quickly. Artificial sandy beaches focus on beach width stability and evolution. This paper is based on an artificial beach project in Haikou Bay, where, in view of the existing conditions, a new type of beach profile that can protect beach berm and width without being eroded by large wave action. Numerical simulation based on XBeach model were conducted to predict the morphodynamical responses of the beach, including a diagnosis of the erosion spots under storm and normal wave events, respectively. Sediment fluxes along and across the shoreline under varied scenarios, dependent on profile width and backshore slope, were discussed. It was found that normal waves with lower heights and longer periods can induce stronger erosion than storm waves due to the landform of the inner-bay in Haikou Bay. Engineering and biological methods to reduce beach erosion during wave action were discussed. Biological methods such as green-plants-root-system can retain berm surface sediment without allowing it to be transported offshore by wave action. The design concept of this artificial beach project may inspire more beach design and protection projects in coastal zones.
- Published
- 2023
- Full Text
- View/download PDF
35. Experimental research on dynamic responses and hydrodynamic pressures of deep-water bridge piers under seismic and wave actions.
- Author
-
Chen, Yu, Huang, Xin, Wu, Kun, and Li, Zhong-Xian
- Subjects
- *
BRIDGE foundations & piers , *SEISMIC waves , *SHAKING table tests , *EFFECT of earthquakes on bridges , *EARTHQUAKE magnitude - Abstract
Earthquakes and extreme waves pose significant threats to the safety of offshore bridges, particularly in deep-water environments. The temporal sequence of earthquakes and waves and the specific type of earthquake are critical factors that contribute to the potential risks involved. This study aimed to fill a key knowledge gap by conducting a comprehensive series of physical tests on a deep-water bridge pier at a scale factor of 1:30. White noise tests, shaking table tests, wavemaker tests, and combined shaking table and wavemaker tests were carried out. Near-field pulsed earthquakes, far-field long-period earthquakes and earthquake-wave phase differences were examined in the tests. The test results indicate that the presence of water has a noticeable impact on the natural frequency, particularly the 2nd-order frequency, of bridge piers, which may significantly influence the dynamic responses of high bridge piers. The effects of water–pier interactions are further intensified by seismic actions such as the pulsed Loma Prieta and long-period Chi-Chi earthquakes. Moreover, the earthquake-induced hydrodynamic pressures on the upstream and downstream faces of the pier are nearly identical, whereas there is a notable difference when the pressures are caused by incident waves. The magnitude of the combined earthquake and wave responses in relation to the individual responses is influenced by the earthquake–wave phase differences, and the combined responses are less than the sum of the individual responses. • Dynamic responses of bridge piers to earthquakes and waves are investigated and carried out through joint tests. • Phase differences between earthquakes and waves are emphasized, and pulsed and long-period earthquakes are considered. • The effect of combined action on bridge pier responses and the distribution of hydrodynamic pressures are summarized. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
36. Nonlinear Wave Control Actions to Increase Oil Recovery of Natural Reserves.
- Author
-
Akhmetzyanov, A. V. and Samokhin, A. V.
- Subjects
- *
NONLINEAR waves , *HARMONIC oscillators , *SHOCK waves , *PETROLEUM reservoirs , *OIL fields - Abstract
When developing oil fields, periodic wave disturbances are used to increase the well flow rate and increase the ultimate oil recovery of the reservoirs. In an inhomogeneous medium, in the presence of dissipation and/or dispersion, the harmonic oscillations generated in the well bottoms turn into sawtooth waves with periodic shock fronts. The article describes and investigates oneand two-dimensional nonlinear mathematical models of such processes. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
37. Wave exposure, shore level, and season of clearing modulate early algal abundance and succession in an intertidal zone.
- Author
-
Mayakun, Jaruwan, Prathep, Anchana, and Kim, Jeong Ha
- Subjects
- *
INTERTIDAL zonation , *PHYSIOLOGICAL adaptation , *SEASONS , *ULVA , *BANGIALES , *RED algae , *BROWN algae , *CERAMIALES - Abstract
SUMMARY: Zonation patterns and the structure of intertidal communities are controlled by tidal conditions. Algal diversity, abundance and succession were experimentally tested under different degrees of wave exposure, shore level, and season of clearing at the intertidal zone, Phuket, Thailand. Dead coral patches colonized by algae (20 cm × 20 cm) were cleared at upper, middle, and lower shore levels on sheltered and semi‐exposed shores during both the dry and rainy seasons. Of 17 algal species, including eight Rhodophyta, eight Chlorophyta, and one Phaeophyceae that were recruited on the cleared plots, three species were dominant: Ulva paradoxa, Padina in the Vaughaniella stage, and Polysiphonia sphaerocarpa. Algal diversity on the semi‐exposed shore was higher than on the sheltered shore. In the successional process, U. paradoxa extensively recruited and persisted longer on plots cleared at the middle shore level on the semi‐exposed shores than at the other. It showed a greater abundance in the plots cleared in the rainy season than those cleared in the dry season. Ulva paradoxa persisted for around 5 to 6 months after clearing and was then replaced by the two later species, Padina in the Vaughaniella stage and P. sphaerocarpa. Ulva paradoxa settled more easily and persisted longer at the cleared plots than other algal species because of its opportunistic characteristics and a special physiological adaptation to long periods of emersion. From this study, degree of wave exposure, shore level, and season of clearing likely play important roles in algal recruitment, abundance, and succession patterns. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
38. Utilization of Geotextile Fabric and Permeable Concrete to Prevent Coastal Erosion
- Author
-
Ramkrishnan, R., Narayana Pillai, N., Aziz, Azhar, Gowri, R., Shehata, Hany Farouk, Editor-in-Chief, El-Zahaby, Khalid M., Advisory Editor, Chen, Dar Hao, Advisory Editor, Wang, Shuying, editor, Xinbao, Yu, editor, and Tefe, Moses, editor
- Published
- 2019
- Full Text
- View/download PDF
39. Determining the Structural Frame Damage Mechanisms of Deep-Sea Manned Submersibles.
- Author
-
Ding, Zhongjun, Zhang, Yi, Wang, Yifan, and Zhao, Qingxin
- Subjects
- *
STRUCTURAL frames , *YIELD stress , *SUBMERSIBLES , *OCEAN conditions (Weather) , *FINITE element method , *STRENGTH of materials , *OCEAN waves - Abstract
Ding, Z.; Zhang, Y.; Wang, Y., and Zhao, Q., 2022. Determining the structural frame damage mechanisms of deep-sea manned submersibles. Journal of Coastal Research, 38(1), 77–85. Coconut Creek (Florida), ISSN 0749-0208. Deployment and recovery data describing the service life of the Jiaolong-manned submersible and its structural frame damage inspection records suggest that the damage sustained by the structural frame could be related to wave loads when the manned submersible is recovered in rough seas. The computational fluid dynamics simulation was used to calculate the wave loads acting on the manned submersible in this article, and the results were used as inputs for a finite element analysis of the structural frame to evaluate the stress in and displacement of the structural frame during manned submersible recovery in rough seas. The results of this analysis indicated that some of the nodes in the structural frame experienced stresses considerably in excess of the permitted limits and approached the yield strength of the material, representing a severe threat to the safety of the Jiaolong-manned submersible when recovered in rough seas. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
40. Obtaining Starch Nanoparticles with the Use of Intensifying Resonance Wave Action.
- Author
-
Ganiev, S. R., Kasilov, V. P., Kislogubova, O. N., Butikova, O. A., and Kochkina, N. E.
- Abstract
In the present study, starch nanoparticles are obtained by precipitation intensified using resonance wave action. The formation of starch nanoparticles is confirmed by dynamic light scattering, scanning electron microscopy, and X-ray diffraction analysis. It is shown that the starch nanoparticles formed are spheres with a diameter ranging from 28 to 160 nm. The results can be applied in creating new energy- and resource-saving techniques for the formation of functional starch nanoparticles. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
41. CFD prediction of ship-bank interaction for KCS under extreme conditions.
- Author
-
Liu, Han, Ma, Ning, and Gu, Xiechong
- Subjects
- *
CONTAINER ships , *WATER levels , *WATER depth , *VISCOUS flow , *TORQUE , *COMPUTATIONAL fluid dynamics - Abstract
When the ship speed exceeds a certain level in shallow water, ship-bank interaction induces great influence on the ship's manoeurability with some special hydrodynamic characteristics, but the mechanism is not totally understood. This paper presents a numerical prediction of the ship-bank interaction for the model of the KRISO Container Ship. An unsteady Reynold-Averaged Navier Stokes solver is applied to simulate the viscous flows. A grid convergence study is performed and the numerical results are compared with the experimental data. The hydrodynamic forces and moments and the squat are computed for different water depths and ship-to-bank distances. Results show that the sway force changes into a repulsive force with respect to the bank under the condition of h = 1.15T or Frh > 0.528 at h = 1.3T, which is due to the change of sway force distribution. The comparison of the results with and without free-surface modelling shows that the wave elevation affects the sway force distribution along the ship significantly. The detailed sway force distributions and wave elevations explain that the wave action between the ship and the bank is the key enabler of the occurrence of the repulsive sway force under the extreme conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
42. INFLUENCE OF WIND WAVES ON THE FLOW IN FLOWING RESERVOIRS
- Author
-
Sobir Eshev, Alisher Khazratov, Ashraf Rahimov, and Shahboz Latipov
- Subjects
wave action ,spectral component ,method of characteristics ,acceleration length ,wave beam ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
ABSTRACT: Methods are given for calculating the formation of wind waves in flowing reservoirs, taking into account oncoming and associated currents and the limitation of acceleration by the banks. ABSTRAK: Kaedah diberikan bagi mengira pembentukan gelombang angin dalam takungan aliran, dengan mengambil kira arus datang dan aliran berkaitan dan kekurangan pecutan pada tebing.
- Published
- 2020
- Full Text
- View/download PDF
43. Estimating relative risk of within-lake aquatic plant invasion using combined measures of recreational boater movement and habitat suitability
- Author
-
Wittmann, Marion E, Kendall, Bruce E, Jerde, Christopher L, and Anderson, Lars W.J.
- Subjects
Dispersal ,Invasive species ,Eurasian milfoil ,Risk assessment ,Wave action ,Suitable habitat - Abstract
Effective monitoring, prevention and impact mitigation of nonindigenous aquatic species relies upon the ability to predict dispersal pathways and receiving habitats with the greatest risk of establishment. To examine mechanisms affecting species establishment within a large lake, we combined observations of recreational boater movements with empirical measurements of habitat suitability represented by nearshore wave energy to assess the relative risk of Eurasian watermilfoil (Myriophyllum spicatum) establishment. The model was evaluated using information from a 17 year (1995–2012) sequence of M. spicatum presence and absence monitoring. M. spicatum presence was not specifically correlated with recreational boater movements; however its establishment appears to be limited by wave action in Lake Tahoe. Of the sites in the “High” establishment risk category (n = 37), 54% had current or historical infestations, which included 8 of the 10 sites with the highest relative risk. Of the 11 sites in the “Medium” establishment risk category, 5 had current or historical M. spicatum populations. Most (76%) of the sites in the “Low” establishment risk category were observed in locations with higher wave action. Four sites that received zero boater visits from infested locations were occupied by M. spicatum. This suggests that the boater survey either represents incomplete coverage of boater movement, or other processes, such as the movement of propagules by surface currents or introductions from external sources are important to the establishment of this species. This study showed the combination of habitat specific and dispersal data in a relative risk framework can potentially reduce uncertainty in estimates of invasion risk.
- Published
- 2015
44. Spatial Distribution of CaCO3 in Biocemented Sandy Slope Using Surface Percolation.
- Author
-
Kou, Hai-lei, Wu, Chuangzhou, Jang, Bo-An, and Wang, Dong
- Subjects
- *
PERCOLATION , *MATERIAL erosion , *EROSION - Abstract
The microbial-induced carbonate precipitation (MICP) technique has been increasingly employed for erosion mitigation and stabilization of sandy slopes. Biocementation can improve the strength and stiffness of unsaturated sand. In this study, the performance of a new biogrouting method (i.e., surface percolation) for sandy slopes under unsaturated conditions was investigated. Model-scale laboratory tests were conducted on MICP-treated coastal slopes to assess the erosion resistance to wave actions. The spatial distribution of CaCO3 in the biocemented sandy slope was measured, which can reveal the mechanism and characteristics of biocementaion of sandy slopes. Results show that the slope surface experienced no obvious erosion after the implementation of MICP treatment for four cycles. The lowest degree of saturation was observed at the slope crest, and it increased to the highest value at the slope toe. Similarly, the erosion resistance was also doubled from the slope crest to the slope toe due to flow of water/solution in the slope in the downward direction. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
45. Biological Cohesion as the Architect of Bed Movement Under Wave Action.
- Author
-
Chen, Xindi, Zhang, Changkuan, Townend, Ian, Paterson, David M., Gong, Zheng, Jiang, Qin, Feng, Qian, and Yu, Xiping
- Subjects
- *
COHESION , *MECHANICAL oscillations , *COASTAL wetlands , *HYDRAULICS , *MICROORGANISMS , *MICROBIAL communities , *MANGROVE ecology - Abstract
Cohesive extracellular polymeric substances (EPS) generated by microorganisms abundant on Earth are regarded as bed "stabilizers" increasing the erosion threshold in sedimentary systems. However, most observations of this phenomenon have been taken under steady flow conditions. In contrast, we present how EPS affect the bed movement under wave action, showing a destabilization of the system. We demonstrate a complex behavior of the biosedimentary deposits, which encompasses liquefaction, mass motion, varying bed formations and erosion, depending on the amount of EPS present. Small quantities of EPS induce higher mobility of the sediments, liquefying an otherwise stable bed. Bed with larger quantities of EPS undergoes a synchronized mechanical oscillation. Our analysis clarifies how biological cohesion can potentially put coastal wetlands at risk by increasing their vulnerability to waves. These findings lead to a revised understanding of the different roles played by microbial life, and their importance as mediators of seabed mobility. Plain Language Summary: The term "ecosystem engineering" emerged in the 1990s, which commonly refers to the activities of larger organisms like mangroves. However, while people think that bigger organisms generate bigger potential engineering effects, there may be microscale organisms who can result in significant impacts on the ecosystems through their number rather than their size. Currently, cohesive extracellular polymeric substances (EPS) generated by microorganisms have been widely reported to increase the threshold for sediment erosion by flowing water, which is known as "biostabilization." However, we demonstrate that this is not the case under wave action. On the contrary, EPS show a destabilization effect of the system, turning an otherwise stable sedimentary bed into "soup." Our analysis clarifies how neglecting even low content of EPS can result in inaccurate prediction of the bed stability and coastal safety under wave action. The risk of bed liquefaction is expected to pose potential threats to wetlands where microbial communities occupy habitats while the production of EPS is much higher. The misinterpretation of the vulnerability of wetlands when exposed to waves could put the existing ecosystems at risk, considering that these ecosystem services are valued at about US$10,000 per hectare. Key Points: Cohesive extracellular polymeric substances largely affect the bed mobility under wave action showing a destabilization of the systemSmall amounts of substrate biological cohesion act to liquefy an otherwise stable bed and increase erosion up to three timesA framework is proposed showing how biological cohesion can put coastal sediment at risk by increasing its vulnerability to waves [ABSTRACT FROM AUTHOR]
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- 2021
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46. Multiple stressors drive convergent evolution of performance properties in marine macrophytes.
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Demes, Kyle W., Starko, Samuel, and Harley, Christopher D. G.
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CONVERGENT evolution , *INTERTIDAL zonation , *EXTREME environments , *THERMAL stresses , *KEY performance indicators (Management) , *MACROPHYTES - Abstract
Summary: Extreme environments have driven the evolution of some of the most inspiring adaptations in nature. In the intertidal zone of wave‐swept shores, organisms face physical forces comparable to hurricanes and must further endure thermal and desiccation stress during low tides, compromising their physiological and biomechanical performance.We examine how these multiple stressors have influenced the evolution of tissue properties during desiccation using eight phylogenetically independent pairs of intertidal and subtidal macrophytes.Intertidal species generally lost water more slowly than their subtidal counterparts, presumably as an adaption to regular emersion. Under partial desiccation, breaking force, strength, and extensibility of intertidal species generally exceeded those of subtidal species, although important differences existed among phylogenetic pairs. This was often true even when subtidal relatives resisted greater forces or were more extensible under full hydration. The interacting effects of mechanical forces and desiccation during low tide are likely a major selective agent in determining macrophyte performance and fitness.Overall, we found that lineages that have independently evolved to occupy the wave‐swept intertidal have converged on performance metrics that are likely to be adaptive to the interacting stressors associated with their extreme niches. [ABSTRACT FROM AUTHOR]
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- 2021
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47. Wave-induced uplift pressure on berm revetment with Seabee slope.
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Zhou, Zijun, Chen, Yongping, Pan, Yi, Shen, Yusheng, and Gan, Min
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PRESSURE , *WATER pressure , *EQUATIONS - Abstract
The berm revetment with a Seabee slope has been widely used in coastal defense structures. It is necessary to understand the distribution of wave-induced uplift pressure as it may cause serious damage to the cover layer of the revetment. Therefore, a series of physical experiments are carried out to quantify the uplift pressure on the revetment under various wave conditions. It is found that the freeboard of the berm is a key parameter which categorizes the laboratory results into two groups. Under negative freeboard, the distribution of uplift pressure on the upper slope is similar to that on the lower slope. Additionally, the maximum uplift pressure on both upper and lower slopes is strongly related to the surf-similarity parameter ξp. Under positive freeboard, the uplift pressure on the lower slope is significantly larger than that of the upper slope. The maximum uplift pressure on the lower slope is similar to that of the conventional rubble mound revetment. At last, Empirical equations are proposed to estimate the maximum relative uplift pressure under positive and negative freeboards. [ABSTRACT FROM AUTHOR]
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- 2020
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48. Wave energy distribution at inlet channel margins as a function of ebb tidal delta morphology: Cananéia Inlet, São Paulo, Brazil
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BRUNA G. AMBROSIO, PAULO H.G.O. SOUSA, MARCELO H. GAGLIARDI, and EDUARDO SIEGLE
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wave action ,ebb tidal delta ,tidal inlet ,numerical modeling ,Science - Abstract
Abstract Wave energy gradients between and along the margins of inlet channels play an important role in defining the inlet margins’ evolutionary processes, mainly those related to spit erosion or accretion, and inlet migration. The aim of this study is to understand the wave power distribution along the margins of a tidal inlet (Cananéia inlet, São Paulo, Brazil), its variation over time, and the influences of the ebb tidal delta morphology on the incoming waves. To evaluate changes in bathymetry and morphology of submersed features, we apply geoprocessing techniques to analyze nautical charts from the Brazilian Navy from 1939, 1971, 1985 and 2004. The numerical model MIKE21 SW was applied to assess wave propagation and nearshore wave power. Hence, wave energy levels along the inlet margins were assessed in terms of decadal morphological changes. The results indicate a dynamic behavior of the inlet and ebb tidal delta, pointing to the ebb tidal delta as the main transforming agent of the waves that reach the inner portion of the channel. The morphological changes of the ebb tidal delta over the last decades are critical to define the action of waves on the margins of the inlet.
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- 2020
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49. Combined Effects of Hillslope-Concentrated Flows and Riverine Stream Waves on Soil Erosion in the Reservoir Riparian Zone
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Yuhai Bao, Yantong Yu, Qiang Tang, Xiubin He, Jie Wei, Yunhua Hu, and Jinlin Li
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bank erosion ,hillslope-concentrated flow ,wave action ,water level fluctuation zone ,Three Gorges Reservoir ,Hydraulic engineering ,TC1-978 ,Water supply for domestic and industrial purposes ,TD201-500 - Abstract
During the exposed season, the water level fluctuation zone of the Three Gorges Reservoir has suffered from hillslope-concentrated flows and riverine stream waves, which considerably complicates the processes and magnifies the rate of bank erosion. This study depicts the forms and patterns of integrated bank erosion in this reservoir marginal landscape, decouples the evolutionary processes involved, explores the underlying mechanisms, and quantifies the magnitude through a case study on a fine-grained sandy bank. Hillslope-concentrated flows over rainfall storm events developed continuous gullies starting from uplands and extending throughout the entire slope of the reservoir bank, characterized by relatively larger depths and widths compared with discontinuous gullies on the lower slope developed by riverine stream waves.
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- 2021
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50. Why do certain species dominate? What we can learn from a rare case of Microdictyon dominance on a Caribbean reef.
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Dell, Claire L. A., Longo, Guilherme O., Manfrino, Carrie, and Burkepile, Deron E.
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CORAL reefs & islands , *REEFS , *CORAL communities , *SOCIAL dominance , *CORALS , *BROWN algae , *SPECIES - Abstract
Many Caribbean reefs have shifted from coral dominance to macroalgal dominance, often by brown algae such as Dictyota and Lobophora. However, the north side of Cayman Brac in the Cayman Islands is dominated seasonally by the green macroalga Microdictyon (percent cover of Microdictyon is 4% in the winter and ~40% of the reef in the summer), although it is absent from the south side of the island and the remainder of the country. Indeed, Microdictyon is rare in much of the Caribbean, so this situation on Cayman Brac provides an opportunity to investigate the conditions that facilitate its distribution and dominance. The impact of herbivory, competition, nutrient input and other abiotic conditions were examined as factors that could influence the distribution and dominance of Microdictyon. While herbivory or nutrient input are frequently found to be key drivers of benthic community composition on coral reefs, here consumption of Microdictyon by herbivores was low, and thus, the alga was not subject to strong top‐down control by herbivory. So, in this case, neither herbivore abundance nor feeding preference appeared to influence the distribution of Microdictyon. Nutrient input was also similar to both sides of the island suggesting nutrients played little role in differential distribution. But, in a controlled transplant experiment where Microdictyon was protected from herbivory and competition, it experienced almost complete mortality (93.3%) when transplanted to the south side, compared to only 11.8% mortality on the north. The south side was exposed to the strongest wave action 92% of the days in our study and was on average a slight, but significant 0.2°C warmer. Thus, these data suggest physical forcing (i.e. wave exposure) is the most likely factor dictating Microdictyon distribution. Conversely, a combination of reduced herbivory and increased competitive strength may explain the seasonal dominance of Microdictyon on the north side of Cayman Brac. Microdictyon was a competitive inferior to the other common algae in winter but increased in competitive strength to equal other species in summer. These results add to the literature on Microdictyon and on the forces impacting benthic community structure of coral reefs. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
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