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1
Yiew, Lucas J., and Allan R. Magee. "Deriving tidal currents from AIS data." Journal of Physics: Conference Series 2311, no. 1 (July 1, 2022): 012003. http://dx.doi.org/10.1088/1742-6596/2311/1/012003.
Повний текст джерелаАнотація:
Abstract In this study, a method is proposed to derive ocean surface current conditions using only information available through AIS – mainly speed over ground (SOG), course over ground (COG) and vessel heading. This method allows the mapping of current conditions over large areas, in doing so gives seafarers better awareness and advance warning of local environmental conditions. This also helps in route planning and management of voyage-related resources. In the proposed method, current speeds and directions are solved through a system of equations containing the resolved SOG, COG and heading of multiple ships. This method was tested using mathematical manoeuvring models, and then subsequently using AIS data collected from vessel traffic in the Western Singapore Straits. Current predictions using this method are validated against physics-based depth-averaged hydrodynamic models driven by astronomical tidal forcing.
2
Li, Wei, and Zhenghua Su. "EFFECTS OF HYPERCONCENTRATION-RELATED DRAG REDUCTION ON TIDAL PROPAGATION IN THE QIANTANG ESTUARY." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 70. http://dx.doi.org/10.9753/icce.v36.currents.70.
Повний текст джерелаАнотація:
The Qiantang Estuary (QE) in the east coast of China is famous for its hyperconcentrated tidal bore with the highest sediment concentration up to about 80 kg/m3 (Pan et al., 2013). Recent research for some European estuaries has indicated that hyperconcentrated environment may affect tidal propagation through hydraulic drag reduction, resulting in an enlarged tidal range and even a regime shift in the estuary (Winterwerp and Wang, 2013). However, this water-sediment interactions have not been considered in the tidal prediction of the Qiantang Estuary in the past. Instead, a bed roughness even smaller than that of glossy glass has often been used to fit the observed tidal data in the mathematical modelling.
Therefore, the present study aims to reveal whether the hyperconcentration-related drag reduction can explain the mechanism of very small bed roughness in the Qiantang Estuary and to what extent it can affect the tidal propagation especially for the tidal range. First, an analytical model is used to predict the tidal range along the QE (from Wenyan to Ganpu stations) for different methods of bed friction. Then, mathematical modelling is conducted to shed light on the processes of tidal wave propagation for the corresponding approaches. The results of the two models are compared together with the field observations to further verify the ability of the analytical model and the significance of the effects of hyperconcentration-related drag reduction.
3
Roberts, W., P. Le Hir, and R. J. S. Whitehouse. "Investigation using simple mathematical models of the effect of tidal currents and waves on the profile shape of intertidal mudflats." Continental Shelf Research 20, no. 10-11 (July 2000): 1079–97. http://dx.doi.org/10.1016/s0278-4343(00)00013-3.
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4
Yu, Feng, and Yong Yin. "Oil Spill Visualization Based on the Numeric Simulation of Tidal Current." International Journal of Virtual Reality 8, no. 2 (January 1, 2009): 71–74. http://dx.doi.org/10.20870/ijvr.2009.8.2.2727.
Повний текст джерелаАнотація:
This paper proposes an approach to implement the 3D visualization of oil spill based on tidal hydrodynamic model. It simulates tidal current of M2 component tide in Jiaozhou Bay. The simulation results conform to the tidal theory and probably conform to the flow measurement report of crude oil pier Phase III at Qingdao Harbor. Based on tidal current and eye-point related adaptive ocean surface mesh model, by analyzing the drift and diffusion mathematical models of oil spill on the sea, the dynamic visualization of drift and diffusion course of oil on the sea were implemented, the visualization result is satisfactory.
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Bailly du Bois, Pascal, Franck Dumas, Mehdi Morillon, Lucille Furgerot, Claire Voiseux, Emmanuel Poizot, Yann Méar, and Anne-Claire Bennis. "The Alderney Race: general hydrodynamic and particular features." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2178 (July 27, 2020): 20190492. http://dx.doi.org/10.1098/rsta.2019.0492.
Повний текст джерелаАнотація:
This study presents an overview of the main hydrodynamic features of the Alderney Race strait based on in situ measurements and two-dimensional hydrodynamic model simulations. The strait encompasses a large amplitude of tidal properties (tidal range and tidal wave propagation) and particularly strong currents exceeding 5 m s −1 with associated counter currents and gyres. Variations in depth, sea bottom roughness, coastal topography and current orientation around the La Hague Cape provide access to a large variety of original hydrodynamic regimes. Some are revealed as locations with a 0.4 m drop in the mean sea level associated with strong average currents. A resonance effect associated with the offshore currents can also be observed close to the coasts. The ‘St Martin whistle’ occurs in a bay whose gyre centre oscillates with a reversal of the measured current every 5–7 min. The Alderney Race represents a particular area of interest for coastal hydrodynamic studies. The available in situ measurement datasets are rich with recordings of: sea levels; acoustic Doppler current profiler current profiles; surface radar currents; waves; dye experiments; surface and in-depth dissolved tracer surveys. Combined with hydrodynamic models, the complexity of this area can be further understood and knowledge of the hydrodynamic process and forcing parameters can be refined, which can be applied to other coastal areas. This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race’.
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Li, Wen Dan, and Meng Guo Li. "Suspension-Diffusion Mathematical Model Calculation for Wenzhou Shoal in Construction Period." Advanced Materials Research 1065-1069 (December 2014): 453–56. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.453.
Повний текст джерелаАнотація:
By means of natural condition and mathematical models of tidal flow and sediment, numerical study is carried out on suspension-diffusion in construction period after the reclamation project of Wenzhou shoal at Oujiang estuary in this paper. The main conclusions are: the suspension-diffusion is controlled by tidal current. The range of suspended sediment concentration more than 10mg/L is mostly in Wenzhou shoal area during filling sand construction, which is the continuous operation. Riprap construction is Instantaneous work; the range of scatter is limited.
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Dyke, P. P. G. "Water circulation in the Firth of Forth, Scotland." Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 93, no. 3-4 (1987): 273–84. http://dx.doi.org/10.1017/s0269727000006734.
Повний текст джерелаАнотація:
SynopsisThe Firth of Forth, in terms of physical oceanography, is part of the North Sea. The general circulation pattern in the firth must be regarded as largely speculative. There have been insufficient measurements of insufficient quality, and what evidence exists leads to the view that what circulation there is, is sluggish and varies from season to season and from year to year.A description is given of the three principal mechanisms that contribute to circulation. Tides, due initially to astronomical forces, manifest themselves in the Firth of Forth through the rise and fall of the adjacent open sea. This rise and fall, periodic in mid ocean, is no longer strictly so in the firth and neither are the tidal currents. The wind-driven currents in the sea are influenced by the earth's rotation. In the Firth of Forth, some of this influence is retained. Naturally, wind-driven currents are larger near the surface. Finally, when water of different densities meets, overturning causes convection currents. All of these effects are present to some extent in the Firth of Forth. In addition, specific account has to be taken of complicated coastal and bottom topography and river outflow. Some attempt to bring together these effects and available measurements is made in this paper. Lastly, several theoretical models are proposed which account for the magnitudes and directions of the observed steady circulation. Mathematical details are given in appendices.
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Li, Xinghao, Lin Yang, Huatang Ren, Zhaowei Liu, and Zeyu Jia. "Analysis of the Invasion of Acetes into the Water Intake of the Daya Bay Nuclear Power Base." Water 14, no. 22 (November 17, 2022): 3741. http://dx.doi.org/10.3390/w14223741.
Повний текст джерелаАнотація:
The invasions of marine organisms into the intake of nuclear power plants threaten the normal operation of such plants. Most published numerical models assumed that marine organisms passively follow the current, but such models neglected their biological swimming ability. In this work, adopting a hydrodynamic mathematical model to replicate the flow around the Daya Bay nuclear power base, the invasion characteristics of Acetes were explored by considering the behavior of biological movement. A concept of biological residual current was introduced to describe biological movements that were dominated by both tidal current and biological swimming ability. The biological residual currents near the nuclear power plant were obtained for cases with different nocturnal migration periods (12 h, 13 h, 14 h, 15 h, and 16 h). Using the Lagrangian particle-tracking method, the primary invasion paths of Acetes were obtained, as well as the travel time of Acetes to the intake, based on the biological residual current along monitoring points. The results showed that the invading time for Acetes reaching the water intake of the nuclear power base was significantly decreased when biological migration behavior was considered. When the nocturnal active period was over 13 h, it took only 10 days for Acetes to enter the western waters of Daya Bay from the southwest of Da Lajia Island and then continue migrating to the water intake in the nuclear power base. When the nocturnal active period was less than 13 h, it took more than 20 days for Acetes to travel the same distance. The present work provides a new methodology for the simulation and prediction of the migration of marine organisms.
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Pani, Paolo, and Andrea Maselli. "Love in extrema ratio." International Journal of Modern Physics D 28, no. 14 (October 2019): 1944001. http://dx.doi.org/10.1142/s0218271819440012.
Повний текст джерелаАнотація:
The tidal deformability of a self-gravitating object leaves an imprint on the gravitational-wave signal of an inspiral which is paramount to measure the internal structure of the binary components. We unveil here a surprisingly unnoticed effect: in the extreme mass-ratio limit the tidal Love number of the central object (i.e. the quadrupole moment induced by the tidal field of its companion) affects the gravitational waveform at the leading order in the mass ratio. This effect acts as a magnifying glass for the tidal deformability of supermassive objects but was so far neglected, probably because the tidal Love numbers of a black hole (the most natural candidate for a compact supermassive object) are identically zero. We argue that extreme mass-ratio inspirals detectable by the future laser interferometric space antenna (LISA) mission might place constraints on the tidal Love numbers of the central object which are roughly eight orders of magnitude more stringent than current ones on neutron stars, potentially probing all models of black hole mimickers proposed so far.
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Li, Tilai, Xiangyu Gao, Xinzhou Zhang, and Yinshuang Wang. "IMPACT OF RUNOFF ON SALT INTRUSION OF YANGTZE ESTUARY." Coastal Engineering Proceedings 1, no. 32 (February 2, 2011): 49. http://dx.doi.org/10.9753/icce.v32.management.49.
Повний текст джерелаАнотація:
Based on one-dimensional and two-dimensional mathematical coupling models of tidal current and salinity from Datong to Yangtze estuary, the impacting scope of salt intrusion are calculated when the runoff of Datong from 4,500m3/s to 30,000m3/s, and the maximum and average value of salinity at each representative point of the estuary are given. When flow of Datong is less than 10,000 m3/s, if projects of water transfer, pumping and diversion are not taken into account at the lower reaches of Datong, the maximum salinity at the downstream reaches of Xuliujing and the average salinity at the downstream reaches of Baimaosha will exceed drinking water criteria.
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Yao, Gang, Shuxiu Pang, Tingting Ying, Mohamed Benbouzid, Mourad Ait-Ahmed, and Mohamed Fouad Benkhoris. "VPSO-SVM-Based Open-Circuit Faults Diagnosis of Five-Phase Marine Current Generator Sets." Energies 13, no. 22 (November 17, 2020): 6004. http://dx.doi.org/10.3390/en13226004.
Повний текст джерелаАнотація:
Generating electricity from enormous energy contained in oceans is an important means to develop and utilize marine sustainable energy. An offshore marine current generator set (MCGS) is a system that runs in seas to produce electricity from tremendous energy in tidal streams. MCGSs operate in oceanic environments with high humidity, saline-alkali water, and impacts of marine organisms and waves, and consequently malfunctions can happen along with the need for expensive inspection and maintenance. In order to achieve effective fault diagnosis of MCGSs in events of failure, this paper focuses on fault detection and diagnosis (FDD) of MCGSs based on five-phase permanent magnet synchronous generators (FP-PMSGs) with the third harmonic windings (THWs). Firstly, mathematical models were built for a hydraulic turbine and the FP-PMSG with THWs; then, a fault detection method based on empirical mode decomposition (EMD) and Hilbert transform (HT) was studied to detect different open-circuit faults (OCFs) of the generator; afterwards, a variable-parameter particle swarm optimization (VPSO) was designed to optimize the penalty and kernel function parameters of a support vector machine (SVM), which was named the VPSO-SVM method in this paper and used to perform fault diagnosis of the FP-PMSG. Finally, simulation blocks were built with MATLAB/Simulink to realize the mathematical models of the MCGS, and the proposed FDD method was coded with MATLAB. The effectiveness of the proposed VPSO-SVM method was validated by simulation results analysis and comparisons.
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Bandeira, Jefferson V., and Lécio H. Salim. "Technetium-99m: From nuclear medicine applications to fine sediment transport studies." Nukleonika 62, no. 4 (December 1, 2017): 295–302. http://dx.doi.org/10.1515/nuka-2017-0043.
Повний текст джерелаАнотація:
Abstract The present work is a contribution to rescue the history of development of the application of 99mTc, widely used in nuclear medicine, to its use as tracer for the study of the transport of fine sediment in suspension, in water environment. It addresses the usefulness of its application in obtaining important parameters in environmental studies, illustrating them with some applications already performed and the results obtained. This kind of study, when associated with information on hydrodynamic parameters, for example, river, tidal, wind and wave currents, are powerful tools for the understanding and quantification of fine sediment transport in suspension. Fine sediment is an important vector in the transportation of heavy metals, organic matter and nutrients in water environment, and the quantitative knowledge of its behaviour is mandatory for studies of environmental impacts. Fine sediment labelled with 99mTc, can also be used to study the effect of human interventions, such as dredging of reservoirs, access channels and harbours, and the dumping of dredged materials in water bodies. Besides that, it can be used to optimize dredging works, evaluating the technical and economic feasibility of dumping sites and their environmental impact. It is a valuable support in the calibration and validation of mathematical models for sediment dynamics.
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Liu, X. "A NEW FRAMEWORK FOR ACCURACY ASSESSMENT OF LIDAR-DERIVED DIGITAL ELEVATION MODELS." ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences V-4-2022 (May 18, 2022): 67–73. http://dx.doi.org/10.5194/isprs-annals-v-4-2022-67-2022.
Повний текст джерелаАнотація:
Abstract. Existing approaches to accuracy assessment of LiDAR-derived DEM are typically based on statistical methodology and focus on vertical accuracy. This paper presents a new framework which calls for assessment of not only a DEM’s vertical accuracy, but also its ability to preserve a point’s elevation rank in the bare earth topographic surface. New methods to assess each aspect are presented. For DEM’s vertical accuracy, approximation theory from numerical analysis is used to quantify the total error at each DEM point as well as its three error components – sensor error, ground error, and interpolation error. For DEM’s elevation order which is critical to model terrain structure, the concept of isomorphism in set theory is drawn as the mathematical rationale and Kendall’s rank correlation efficient is used to quantify the accuracy. The new framework is illustrated using a DEM derived from LiDAR for sea-level rise vulnerability assessment of a tidal salt marsh. Compared to conventional methods based on statistics, the new framework and methods produce detailed mapping of error distribution thus enable the identification of the main sources of error and where improvement is needed most. Results call for re-evaluation of the current practice of assessing filtering accuracy in LiDAR data processing and further research on relative elevation and isomorphism.
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Wu, Y., R. A. Falconer, and J. Struve. "Mathematical modelling of tidal currents in mangrove forests." Environmental Modelling & Software 16, no. 1 (January 2001): 19–29. http://dx.doi.org/10.1016/s1364-8152(00)00059-1.
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Ellis, Kathryn K., Timothy Callahan, Dianne I. Greenfield, Denise Sanger, Joshua Robinson, and Martin Jones. "Measuring and Modeling Flow Rates in Tidal Creeks: A Case Study from the Central Coast of South Carolina." Journal of South Carolina Water Resources, no. 4 (June 1, 2017): 21–39. http://dx.doi.org/10.34068/jscwr.04.03.
Повний текст джерелаАнотація:
The purpose of this study was to collect site- and condition-specific hydrology data to better understand the water flow dynamics of tidal creeks and terrestrial runoff from surrounding watersheds. In this paper, we developed mathematical models of tidal creek flow (discharge) in relation to time during a tidal cycle and also estimated terrestrial runoff volume from design storms to compare to tidal creek volumes. Currently, limited data are available about how discharge in tidal creeks behaves as a function of stage or the time of tide (i.e., rising or falling tide) for estuaries in the southeastern United States, so this information fills an existing knowledge gap. Ultimately, findings from this study will be used to inform managers about numeric nutrient criteria (nitrogen-N and phosphorus-P) when it is combined with biological response (e.g., phytoplankton assemblages) data from a concurrent study. We studied four tidal creek sites, two in the Ashepoo-Combahee-Edisto (ACE) Basin and two in the Charleston Harbor system. We used ArcGIS to delineate two different watersheds for each study site, to classify the surrounding land cover using the NOAA Coastal Change Analysis Program (C-CAP) data, and to analyze the soils using the NRCS Soil Survey Geographic database (SSURGO). The size of the U.S. Geological Survey’s Elevation Derivatives for National Application (EDNA) watersheds varied from 778 to 2,582 ha; smaller geographic watersheds were delineated for all sites (except Wimbee) for stormwater modeling purposes. The two sites in Charleston Harbor were within the first-order Horlbeck Creek and the second-order Bulls Creek areas. The ACE Basin sites were within the third-order Big Bay Creek and the fourth-order Wimbee Creek areas. We measured the stage and discharge in each creek with an acoustic Doppler current profiler (ADCP) unit for multiple tide conditions over a 2-year period (2015–2016) with the goal of encompassing as large of a range of tide stage and discharge data measurements as possible. The Stormwater Runoff Modeling System (SWARM) was also used to estimate the potential water entering the creeks from the land surface; this volume was very small relative to the tide water volume except for the more-developed Bulls Creek watershed. The results show that the peak discharge occurred on the ebb tide and that the duration of the flood tide spanned a longer period of time; both of these observations are consistent with traits associated with an ebb-dominated tidal creek system. The tidal inflow and outflow (flood and ebb tides, respectively) showed an asymmetrical pattern with respect to stage and discharge; peak discharge during the flood (rising) tide occurred at a higher stage than for the peak discharge during the ebb (falling) tide. This is not an unexpected result, as the water on an ebb tide is moving down gradient funneled through the creek channel toward the coast. Furthermore, water moving with the rising flood tide must overcome frictional losses due to the marsh bank and vegetation; i.e., the peak discharge can only happen when the water has risen above these impediments. We infer from the flow dynamics data that faster water velocities during ebb tide imply that more erosive energy could transport a larger mass of suspended solids and associated nutrients (e.g., orthophosphate) from the estuary to the coastal ocean. However, the discharge and runoff modeling indicate that land-based flux was important in the developed Bulls Creek watershed, but not at the larger and less-developed Big Bay Creek watershed. At Big Bay Creek, the relatively large tidal discharge volume compared to the smaller potential runoff generated within the watershed indicates that the creek could potentially dilute terrestrial runoff contaminants. Smaller, more-urbanized tidal wetland systems may not benefit from such dilution effects and thus are vulnerable to increased runoff from adjacent developed landscapes.
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Troude, Jean-Pierre, and Jean-Baptiste Sérodes. "Caractéristiques hydrodynamiques d'un estran à forte sédimentation." Canadian Journal of Civil Engineering 17, no. 2 (April 1, 1990): 148–55. http://dx.doi.org/10.1139/l90-019.
Повний текст джерелаАнотація:
In the St. Lawrence estuary (Canada), tidal flats localized in the area of saline intrusion are covered with up to 30 cm of fine sedimentation during July, August, and September. This sedimentation is the result of waters coming from the turbidity zone. The upper half of the tidal flats are covered with a tidal marsh. This vegetation is very important in preventing the sediments from eroding. In the tidal marsh, measurements with automatic current meters were taken during periods longer than a month. These showed that, among the vegetation, currents are weak and steady during spring tides and neap tides, whereas next to the drainage systems, currents are heavily dependant on the range of the tide. Close to the shore, currents decrease significantly, thus helping fine sedimentation to occur. A mathematical simulation of the currents made on a line perpendicular to the shore shows the impact of the vegetation on the formation of the drainage system in the tidal flats. Water entrapment by the vegetation at the end of the flood initiates the creation of creeks and insures their continuity throughout the summer. As soon as the vegetation is destroyed, creeks fill up with sediments and disappear from the surface of the tidal marsh. Contrary to what could be assumed, the mathematical model also shows that spring tides, even though associated with strong currents, promote a very active sedimentation on the tidal marsh. In the St. Lawrence estuary, erosion of the mud flats deposits is observed during short periods of strong winds in summer. This high energy and high variability do explain the strong year to year variation in sedimentation observed in the tidal flats. Key words: currents, intertidal sedimentation, tidal creeks, tidal flats.
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De Vriend, H. J., and J. S. Ribberink. "A QUASI-3D MATHEMATICAL MODEL OF COASTAL MORPHOLOGY." Coastal Engineering Proceedings 1, no. 21 (January 29, 1988): 125. http://dx.doi.org/10.9753/icce.v21.125.
Повний текст джерелаАнотація:
A semi-analytical model of 3D nearshore currents and sediment transport is presented. It describes the tidal motion, the waves, the surfzone currents and the sediment transport in complex coastal areas. The results of a first application, to a well-documented case at the Dutch coast, indicate the potential and the shortcomings of the model. The latter are analysed and suggestions for improvement are given.
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Harder, J. A. "THE ANALYSIS OF HARBOR AND ESTUARY SYSTEMS." Coastal Engineering Proceedings 1, no. 8 (January 29, 2011): 9. http://dx.doi.org/10.9753/icce.v8.9.
Повний текст джерелаАнотація:
It is one of the paradoxes of our age that hydraulic engineering is concerned with problems that in many ways exceed in difficulty those encountered in the more glamorous fields of science. One measure of this situation is that classical mathematics, which is a powerful tool when applied to simple systems, has proved to be a rather impotent aid m hydraulic calculations, except when the geometry is simple. Harbor and estuary systems are usually associated with complex geometry, and thus we ordinarily cannot depend on mathematics to give general solutions. Instead of solving the hydraulic equations of flow in the complex geometry, we have sought to reconstruct the geometry of the prototype in a reduced scale, by means of models, and by assuming that the equations governing the full-size and reduced-scale systems are the same, to find specific solutions through direct measurements in the latter. Because of scale effects, the hydraulic model is not perfect, but it does reproduce the complex geometry and some of the complexities of three dimensional flows in the prototype. These cannot at present be described mathematically, and where they are important a properly constructed and adjusted hydraulic model is our most powerful tool in the investigation of estuarial problems, and is likely to remain so.
However, hydraulic models are very expensive, especially if they are built to a reasonably large scale, so it behooves us to be sure that we have not overlooked other, perhaps less powerful, methods when we are confronted with a particular problem. Within the past decade two methods have been developed that will eventually replace hydraulic models for tidal flow and river flood routing investigations. One is based on the use of digital computers to numerically integrate the differential equations of open channel flow; the realization of this method by a digital computer program for a particular system has been called a "mathematical model". The second is based on the use of analog elements that behave with respect to electrical current in the same way as the prototype behaves with respect to flows of water. When an assembly of such elements is adjusted to duplicate the behavior of a hydraulic system in a way similar to the way a hydraulic model is adjusted during its verification period, the result may be called an analog model.
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Green, J. A. Mattias, and Jonas Nycander. "A Comparison of Tidal Conversion Parameterizations for Tidal Models." Journal of Physical Oceanography 43, no. 1 (January 1, 2013): 104–19. http://dx.doi.org/10.1175/jpo-d-12-023.1.
Повний текст джерелаАнотація:
Abstract The conversion of barotropic to baroclinic tidal energy in the global abyssal ocean is calculated using three different formulations. The calculations are done both “offline,” that is, using externally given tidal currents to estimate the energy conversion, and “online,” that is, by using the formulations to parameterize linear wave drag in a prognostic tidal model. All three schemes produce globally integrated offline dissipation rates beneath 500-m depth of ~0.6–0.8 TW for the M2 constituent, but the spatial structures vary significantly between the parameterizations. Detailed investigations of the energy transfer in local areas confirm the global results: there are large differences between the schemes, although the horizontally integrated conversion rates are similar. The online simulations are evaluated by comparing the sea surface elevation with data from the TOPEX/Poseidon database, and the error is then significantly lower when using the parameterization provided by Nycander than with the other two parameterizations examined.
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Shapiro, G. I. "Effect of tidal stream power generation on the region-wide circulation in a shallow sea." Ocean Science Discussions 7, no. 5 (October 21, 2010): 1785–810. http://dx.doi.org/10.5194/osd-7-1785-2010.
Повний текст джерелаАнотація:
Abstract. Ocean tides are deemed to become a stable source of renewable energy for the future. Tidal energy has two components, the first is the potential energy due to sea level variations and the second comes from the kinetic energy of the tidal streams. This paper is concerned with the backward effect on the ocean currents by a tidal stream farm located in the open shallow sea. Recent studies in channels with 1-D models have indicated that the power potential is not given purely by the flux of kinetic energy, as has been commonly assumed. In this study, a 3-D ocean circulation model is used to estimate (i) maximum extractable energy at different levels of rated generation capacity of the farm, (ii) changes in the strength of currents due to energy extraction, and (iii) alterations in the pattern of residual currents and pathways of passive tracers. As water flow is influenced both by tidal and non-tidal currents, the model takes into account wind-driven and density-driven currents generated by meteorological forcing. Numerical modelling has been carried out for a hypothetical circular farm located in the Celtic Sea north of Cornwall, an area known for its high level of tidal energy. Modelling results clearly indicate that extracted power does not grow linearly with the increase in the rated capacity of the farm. For the case studies covered in this paper, a 100-fold increase in rated generation capacity of the farm results only in 7-fold increase in extracted power, this loss of efficiency is much greater than was estimated earlier with 1-D models. In case of high rated capacity of the farm, kinetic energy of currents is altered significantly as far as 10–20 km away from the farm. At high levels of extracted energy the currents tend to avoid flowing through the farm, an effect which is not captured with 1-D models. Residual currents are altered as far as a hundred kilometres. The magnitude of changes in the dispersion of tracers is highly sensitive to the location. For the drifters analysed in this study, variations in the end-to-start distance due to energy extraction range from 13% to 238%.
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Cheng, Peng, Arnoldo Valle-Levinson, and Huib E. de Swart. "Residual Currents Induced by Asymmetric Tidal Mixing in Weakly Stratified Narrow Estuaries." Journal of Physical Oceanography 40, no. 9 (September 1, 2010): 2135–47. http://dx.doi.org/10.1175/2010jpo4314.1.
Повний текст джерелаАнотація:
Abstract Residual currents induced by asymmetric tidal mixing were examined for weakly stratified, narrow estuaries using analytical and numerical models. The analytical model is an extension of the work of R. K. McCarthy, with the addition of tidal variations of the vertical eddy viscosity in the longitudinal momentum equation. The longitudinal distribution of residual flows driven by asymmetric tidal mixing is determined by the tidal current amplitude and by asymmetries in tidal mixing between flood and ebb. In a long channel, the magnitude of the residual flow induced by asymmetric tidal mixing is maximum at the estuary mouth and decreases upstream following the longitudinal distribution of tidal current amplitude. Larger asymmetry in tidal mixing between flood and ebb produces stronger residual currents. For typical tidal asymmetry, mixing is stronger during flood than during ebb and results in two-layer residual currents with seaward flow near the surface and landward flow near the bottom. For reverse tidal asymmetry, mixing is weaker during flood than during ebb and the resulting residual flow is landward near the surface and seaward near the bottom. Also, the residual flow induced by tidal asymmetry has the same order of magnitude as the density-driven flow and therefore is important to estuarine dynamics. Numerical experiments with a primitive-equation numerical model [the Regional Ocean Modeling System (ROMS)] generally support the pattern of residual currents driven by tidal asymmetry suggested by the analytical model.
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Zuo, Shu Hua. "Hydrodynamic Mathematical Modeling of the Yangshan Deep-Water Harbor Waters, China." Advanced Materials Research 323 (August 2011): 46–50. http://dx.doi.org/10.4028/www.scientific.net/amr.323.46.
Повний текст джерелаАнотація:
Taking Yangshan sea-area of the Qiqu archipelago as an example, a 2D numerical model of tidal currents is established to study the change of the current field and the influence of branch blocking in different stages of northern port construction, including tide process, velocity and tidal prism, in the main channel waters and the branches. Verifications with the observed data indicate that the simulated results can reflect the current fields in the region. Based on the numerical model it is rechecked and researched the influence of branch blocking in different stages of northern port construction on the changing processes of hydrodynamic, including tide process, velocity and tidal prism, in the main channel waters and the branches. The paper is to provide the scientific basis for the construction of Yangshan Port’s subsequent engineering.
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Sakamoto, K., H. Tsujino, H. Nakano, M. Hirabara, and G. Yamanaka. "A practical scheme to introduce explicit tidal forcing into an OGCM." Ocean Science 9, no. 6 (December 13, 2013): 1089–108. http://dx.doi.org/10.5194/os-9-1089-2013.
Повний текст джерелаАнотація:
Abstract. A practical scheme is proposed to explicitly introduce tides into ocean general circulation models (OGCM). In this scheme, barotropic linear response to the tidal forcing is calculated by the time differential equations modified for ocean tides, instead of the original barotropic equations of an OGCM. This allows for the usage of various parameterizations specified for tides, such as the self-attraction/loading (SAL) effect and energy dissipation due to internal tides, without unintentional violation of the original dynamical balances in an OGCM. Meanwhile, secondary nonlinear effects of tides, e.g., excitation of internal tides and advection by tidal currents, are fully represented within the framework of the original OGCM equations. That is, this scheme drives the OGCM by the barotropic linear tidal currents which are predicted progressively by a tuned tide model, instead of the equilibrium tide potential, without large additional numerical costs. We incorporated this scheme into Meteorological Research Institute Community Ocean Model and executed test experiments with a low-resolution global model. The results showed that the model can simulate both the non-tidal circulations and the tidal motion simultaneously. Owing to the usage of tidal parameterizations such as a SAL term, a root-mean-squared error in the tidal heights is found to be as small as 10.0 cm, which is comparable to that of elaborately tuned tide models. In addition, analysis of the speed and energy of the barotropic tidal currents is found to be consistent with that of past tide studies. The model also showed active excitement of internal tides and tidal mixing. In the future, the impacts of internal tides and tidal mixing should be examined using a model with a finer resolution, since explicit and precise introduction of tides into an OGCM is a significant step toward the improvement of ocean models.
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PADMAN, LAURENCE, SVETLANA EROFEEVA, and IAN JOUGHIN. "Tides of the Ross Sea and Ross Ice Shelf cavity." Antarctic Science 15, no. 1 (February 19, 2003): 31–40. http://dx.doi.org/10.1017/s0954102003001032.
Повний текст джерелаАнотація:
Two new ocean tide models for the Ross Sea including the ocean cavity under the Ross Ice Shelf, are described. The optimum model for predicting ice shelf surface height variability is based on assimilation of gravimetry-derived tidal constituents from the Ross Ice Shelf. Synthetic aperture radar interferograms provide an independent test of model performance. The standard deviation of tide height variability is largest under the eastern ice shelf along the Shirase and Siple Coasts, where it can exceed 0.8 m. The maximum peak-to-peak tidal range in this region is ∼3 m. The best predictor for ocean tidal currents north of the ice front is a dynamics-based model that solves the depth-integrated shallow water equations with a linear representation of benthic friction rather than the more usual quadratic form. Tidal currents over the open Ross Sea are dominated by diurnal, topographically trapped vorticity waves. The strongest modelled currents exceed 1 m s−1 at spring tide in a narrow band along the upper continental slope in the north-western Ross Sea. Typical tidal currents in the central continental shelf area of the Ross Sea are 10–20 cm s−1. Under the ice shelf the typical currents are ∼5 cm s−1.
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El Safty, Hoda, and Patrick Lynett. "SPOT APPLICATION TOOL FOR WAVE DRIVEN NEARSHORE HYDRODYNAMICS." Coastal Engineering Proceedings, no. 35 (June 23, 2017): 19. http://dx.doi.org/10.9753/icce.v35.waves.19.
Повний текст джерелаАнотація:
Nearshore hydrodynamics are driven by a wide spectrum of motions/scales that vary on the order of O (10) m to O (100) km. These scales have different effects on the dynamics of the nearshore areas, and capturing these effects is essential in accurately modeling the nearshore processes such as: mixing and transport of pollutants, wave steeping and/or wave damping, erosion and deposition of sediments, and infragravity wave propagation. For example, in tidal inlets, waves interact with tidal-currents and bathymetry. The presences of waves alter the kinematics and the dynamics of the tidal-currents such as increasing the bottom friction due to wave bottom boundary layer and changing the vertical profile of the horizontal velocity from the well-known log profile. The tidal-currents affect the wave kinematics and dynamics such as Doppler shift, wave refraction, and wave steeping in opposite currents, wave breaking and infragravity wave propagation. The time and length scales of the current are much larger than those of the waves, and modeling this interaction using a single numerical model is numerically expensive. One approach to overcome this issue is through using multi-scale numerical modeling by coupling two or more numerical models. In literature, spectral wave models have been widely coupled with circulation models to study wave-current interaction. These spectral models can provide accurate predictions for wave height but they don’t provide accurate information about nonlinear wave statistics, i.e. wave skewness and asymmetry, which is a key parameter in sediment transport models. On the other hand, the phase-resolving models are capable of providing this information. In the current study, the large-scale circulation model, Delft3D, is coupled with time-domain Boussinesq-type wave model. The use of time domain wave model in the numerical coupling will improve the prediction of various nearshore processes such as: wave breaking and thus infragravity wave release and propagation, combined vertical velocity structure under external forcings of tidal currents. Such an application will fulfill the community needs for a "spot application tool" where we simulate wave-driven processes in a large domain with fine-resolution.
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Johnson, Eric S., and Michael L. Van Woert. "Tidal currents of the Ross Sea and their time stability." Antarctic Science 18, no. 1 (March 2006): 141–54. http://dx.doi.org/10.1017/s0954102006000137.
Повний текст джерелаАнотація:
Current measurements obtained from a sparse array of moorings on the Ross Continental Shelf during the 1980 and 90s are analysed for their tidal constituents. Diurnal (K1 and O1) tides are about five times stronger than semi-diurnal tides, and are strongest near the shelf break in agreement with recent model results. At some energetic locations the diurnal tides are significantly weaker at depth, presumably due to bottom friction. Complex demodulation analysis shows that at some locations the tidal response varies significantly in time. This time variability rises markedly above the noise floor expected from the spectral continuum between tidal bands, and does not scale with tidal bandwidth as would be expected of broadband noise. Further its magnitude is generally proportional to the associated tidal constituent, indicating that it is truly a varying tidal response. Space scales of this tidal instability were not resolved but are less than 150 km, while time scales appear mostly seasonal to interannual. The rms magnitude of the unstable response can be 1/3 of a given component’s mean magnitude, placing substantial limits on the ability of prognostic or even data assimilative models to accurately predict these tides for any specific time period.
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Sakamoto, K., H. Tsujino, H. Nakano, M. Hirabara, and G. Yamanaka. "A practical scheme to introduce explicit tidal forcing into OGCM." Ocean Science Discussions 10, no. 2 (March 7, 2013): 473–517. http://dx.doi.org/10.5194/osd-10-473-2013.
Повний текст джерелаАнотація:
Abstract. A practical scheme is proposed to introduce tides explicitly into ocean general circulation models (OGCM). In this scheme, barotropic linear response to the tidal forcing is calculated by the time differential equations modified for ocean tides, instead of the original barotropic equations of OGCM. This allows usage of various parameterizations specified for tides, such as the self attraction/loading (SAL) effect and energy dissipation due to internal tides, without unintentional violation of the original dynamical balances in OGCM. Meanwhile, secondary nonlinear effects of tides, e.g. excitation of internal tides and advection by tidal currents, are fully represented in the framework of the original OGCM equations. That is, this scheme drives OGCM by the barotropic linear tidal currents which are predicted progressively by a well-tuned tide model, instead of the equilibrium tide potential, without large additional numerical costs. We incorporated this scheme into Meteorological Research Institute Community Ocean Model and executed test experiments with a low-resolution global model. The results showed that the model can simulate both of non-tidal circulations and tidal motion simultaneously. Owing to usage of tidal parameterizations such as a SAL term, a root mean square error in the tidal heights was as small as 10.0 cm, which is comparable to tide models tuned elaborately. In addition, analysis of speed and energy of the barotropic tidal currents was consistent with past tide studies. The model also showed active excitement of internal tides and tidal mixing. Their impacts should be examined using a model with a finer resolution in future, since explicit and precise introduction of tides into OGCM is a significant step toward upgrade of ocean modeling.
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Wang, Chen, Sven Smolders, David P. Callaghan, Jim van Belzen, Tjeerd J. Bouma, Zhan Hu, Qingke Wen, and Stijn Temmerman. "Identifying Hydro-Geomorphological Conditions for State Shifts from Bare Tidal Flats to Vegetated Tidal Marshes." Remote Sensing 12, no. 14 (July 18, 2020): 2316. http://dx.doi.org/10.3390/rs12142316.
Повний текст джерелаАнотація:
High-lying vegetated marshes and low-lying bare mudflats have been suggested to be two stable states in intertidal ecosystems. Being able to identify the conditions enabling the shifts between these two stable states is of great importance for ecosystem management in general and the restoration of tidal marsh ecosystems in particular. However, the number of studies investigating the conditions for state shifts from bare mudflats to vegetated marshes remains relatively low. We developed a GIS approach to identify the locations of expected shifts from bare intertidal flats to vegetated marshes along a large estuary (Western Scheldt estuary, SW Netherlands), by analyzing the interactions between spatial patterns of vegetation biomass, elevation, tidal currents, and wind waves. We analyzed false-color aerial images for locating marshes, LIDAR-based digital elevation models, and spatial model simulations of tidal currents and wind waves at the whole estuary scale (~326 km²). Our results demonstrate that: (1) Bimodality in vegetation biomass and intertidal elevation co-occur; (2) the tidal currents and wind waves change abruptly at the transitions between the low-elevation bare state and high-elevation vegetated state. These findings suggest that biogeomorphic feedback between vegetation growth, currents, waves, and sediment dynamics causes the state shifts from bare mudflats to vegetated marshes. Our findings are translated into a GIS approach (logistic regression) to identify the locations of shifts from bare to vegetated states during the studied period based on spatial patterns of elevation, current, and wave orbital velocities. This GIS approach can provide a scientific basis for the management and restoration of tidal marshes.
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Choo, Jian Feng, Jeng Hei Chow, and Pavel Tkalich. "Prediction of tidal-driven currents using convolutional neural network." Journal of Physics: Conference Series 2311, no. 1 (July 1, 2022): 012023. http://dx.doi.org/10.1088/1742-6596/2311/1/012023.
Повний текст джерелаАнотація:
Abstract Efficient forecasting models of coastal currents are required for the predictive control of smart vessels with autonomous or remote operating capabilities. Accurate physics-based numerical models demand computational resources that often are unavailable onboard ships; moreover, internet bandwidth at remote locations might not be sufficient to exchange the large computational files with onshore servers. In this case, light and efficient Data-Driven Models (DDM) may be developed to be used as a surrogate for a physics-based model. Currents and surface elevation are hydrodynamic variables driven by astronomic tide potential, allowing for harmonic analysis and synthesis of otherwise irregular solutions of Navier-Stokes equations. Once numerical solutions are obtained and analysed in the Fourier domain, the identified harmonics (tide constituents) can be used as a dataset to train the DDM. One approach to building a DDM is by utilizing a Convolutional Neural Network (CNN). CNN is mainly applied in image recognition processes, where it learns the spatial features of image matrices of pixels arranged in columns and rows and uses the learned features to predict an output. This approach can be applied to 2D or 3D fields of predominantly tidal-driven coastal currents. This paper extends the CNN framework to approximate and predict coastal hydrodynamic state variables in space and time. The depth-averaged Navier-Stokes equations were used to create the dataset necessary to train the adopted CNN autoencoder architecture. Two methods of CNN model development are explored. The first method assesses CNN’s capabilities for time forward prediction, using 2D time series of hydrodynamic variables. The second method investigates CNN’s parameter (using Manning number) prediction ability using 2D spatial plots formed by the top 20 most energetic tidal constituents that were obtained from the numerical solution. The hyperparameters of the CNN model for both methods were carefully optimized and tuned using the loss function, Root Mean Square Error (RMSE). The coefficient of determination, the relative error of the time series, and its amplitude and phase were used to gauge the performance of the CNN model for both methods at the final testing stage. Once accurate solutions are achieved, the trained DDM is almost instantaneous and uses negligible computational resources as compared to traditional fluid solvers. Therefore, trained DDM can be deployed onboard ships where global forecast information (e.g., from Global Forecast System) can be used to provide an accurate prediction of the current forcing. To generate the instantaneous current predictions for navigation and smart ship control, the global data can be pulled or pushed to the ship before the mission.
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Gross, Markus, and Vanesa Magar. "Wind-Induced Currents in the Gulf of California from Extreme Events and Their Impact on Tidal Energy Devices." Journal of Marine Science and Engineering 8, no. 2 (January 25, 2020): 80. http://dx.doi.org/10.3390/jmse8020080.
Повний текст джерелаАнотація:
Tidal renewable energy is a promising alternative energy resource, and marginal seas are known as excellent sites for tidal energy exploitation. In-stream and tidal energy devices are less exposed to extreme weather events than wind energy. Nevertheless, during tropical storms, the currents may intensify to levels that threaten the integrity of the devices. This paper presents Hurricane Odile and its impact on the currents in the Gulf of California (GC) as a worst case scenario. A methodology to analyze the impact and its potential effects on tidal energy converters installed within the region are presented. The analysis is based on predictions obtained with a 3D shallow water model forced by tides and the meteorological conditions generated by Odile. A tidal model with no wind forcing was used for validation of the tidal model predictions. After validation, the two models were used to analyze the maximum anomaly in surface currents and sea surface height caused by the passage of Odile, and to analyze at which depth the devices could be deemed safe from any impact of the hurricane. Some anomalies extended throughout the water column, even in the deep regions of the GC. This paper highlights the importance of including the meteorological forcing in evaluations of tidal range or in-stream renewable energy resources and introduces new measures of device exposure to the current anomalies.
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Najamuddin, T. Prartono, H. S. Sanusi, I. W. Nurjaya, R. E. Pembonan, H. Umasangaji, Mutmainnah, I. Tahir, and Inayah. "Surface currents modeling based on tidal cycles and monsoon in tropical estuary, Indonesia." IOP Conference Series: Earth and Environmental Science 890, no. 1 (October 1, 2021): 012003. http://dx.doi.org/10.1088/1755-1315/890/1/012003.
Повний текст джерелаАнотація:
Abstract The modeling uses a software-based numerical model DHI MIKE user interface developed by The Danish Hydraulic Institute (DHI) Water and Environment, Denmark. Simulation of current uses a 2-dimensional model (averaging to depth) with a finite element approach. Modeling of currents was conducted to know current dynamics by tidal cycle and seasonal variation (west and east monsoon). The models were validated using correlation coefficient value (r) by comparing direct measurement and model output. The r-value for current velocity during west monsoon was 0.653 and east monsoon was 0.697 and for current direct during west monsoon was 0.887 and the east monsoon was 0.857. While the r-value for the tide was 0.858. All these r values showed a strong correlation and these indicated the models were valid. The result of the simulation of the current models showed that the surface currents were strongly influenced by the tidal cycles. The currents direct flowed to the south at flood tide and to the eastern at ebb tide. The maximum current velocity during the west monsoon was 0.50 m/sec and during the east monsoon was 0.40 m/sec. The averages of currents direct were more dominant eastward of Jeneberang estuary.
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Mazé, Robert, Gilbert Langlois, and François Grosjean. "Tidal Eulerian Residual Currents over a Slope: Analytical and Numerical Frictionless Models." Journal of Physical Oceanography 28, no. 7 (July 1998): 1321–32. http://dx.doi.org/10.1175/1520-0485(1998)028<1321:tercoa>2.0.co;2.
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Korgen, Ben J. "Rule-of-Thumb Formulas for Extending the Versatility of Tidal Current Tables." Marine Technology Society Journal 34, no. 2 (January 1, 2000): 18–21. http://dx.doi.org/10.4031/mtsj.34.2.2.
Повний текст джерелаАнотація:
Four rule-of-thumb formulas have been derived for use in conjunction with existing tidal current tables. For near-surface tidal currents, these formulas yield 1) the percent of time current speed is above a critical value, 2) the percent of time current speed is below a critical value, 3) the time interval when current speed is above a critical value, and 4) the time interval when current speed is below a critical value. The formulas presented require as inputs the near-surface tidal current speed predictions found in standard tidal current tables. Intended for making rough approximations, these formulas may be useful in planning operations for which information on near-surface tidal currents is important. They are not scientific results or predictive models on which anyone’s life should depend. They should be used only with generous safety margins and if possible, with in situ current measurements, since local conditions may vary considerably.
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Devlin, Adam T., Edward D. Zaron, David A. Jay, Stefan A. Talke, and Jiayi Pan. "Seasonality of Tides in Southeast Asian Waters." Journal of Physical Oceanography 48, no. 5 (May 2018): 1169–90. http://dx.doi.org/10.1175/jpo-d-17-0119.1.
Повний текст джерелаАнотація:
AbstractAn analysis of water level time series from 20 tide gauges in Southeast Asia finds that diurnal and semidiurnal astronomical tides exhibit strong seasonal variability of both amplitude and phase, which is not caused by known modulations of the astronomical tide-generating forces. Instead, it is found that the tidal properties are coherent with the western North Pacific monsoon index (WNPMI), indicating that monsoonal mechanisms are the likely cause. The study domain includes the Malacca Strait, Gulf of Thailand, the southern South China Sea, and Java Sea. The character of the geography and the tidal variability is different in each of these subregions. A new barotropic regional tide model is developed that incorporates the coupling between geostrophic currents, wind-driven (Ekman) currents, and tidal currents in the bottom boundary layer in order to examine the influence of these factors on tides. The dynamics thus preserve the frictional nonlinearities while neglecting advective nonlinearities and baroclinic tides, approximations that should be valid on the wide and shallow continental shelves in the study region. The model perturbation approach uses the climatological seasonal variability of wind stress and geostrophic currents, which are prescribed singly and in combination in the model, to explain the observed tidal variability. Results are most successful in the southern Gulf of Thailand and near Singapore, where it is found that the combined effect of geostrophic and Ekman currents shows increased skill in reproducing the tidal variability than individual models. Ambiguous results at other locations suggest more localized processes such as river runoff.
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Jaharuddin and Hadi Hermansyah. "Analytical Approach for Solving the Internal Waves Problems Involving the Tidal Force." Journal of Applied Mathematics 2018 (August 7, 2018): 1–5. http://dx.doi.org/10.1155/2018/6835179.
Повний текст джерелаАнотація:
The mathematical model for describing internal waves of the ocean is derived from the assumption of ideal fluid; i.e., the fluid is incompressible and inviscid. These internal waves are generated through the interaction between the tidal currents and the basic topography of the fluid. Basically the mathematical model of the internal wave problem of the ocean is a system of nonlinear partial differential equations (PDEs). In this paper, the analytical approach used to solve nonlinear PDE is the Homotopy Analysis Method (HAM). HAM can be applied to determine the resolution of almost any internal wave problem involving tidal forces. The use of HAM in the solution to basic fluid equations is efficient and simple, since it involves only modest calculations using the common integral.
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Prytz, A., and M. L. Heron. "On the flushing of Port Phillip Bay: an application of HF ocean radar." Marine and Freshwater Research 50, no. 6 (1999): 483. http://dx.doi.org/10.1071/mf96112.
Повний текст джерелаАнотація:
HF ocean radar can produce maps of surface current in coastal ocean and estuarine waters by providing coverage in both the space and time dimensions. The deployment of COSRAD in Port Phillip Bay for two successive five-day periods provided hourly values of surface currents over the topographically complex area at the south end of the bay. Analysis of the current data provided tidal ellipses for the validation of numerical models, with resultant residual currents of the order of 0·05 m s–1. The repeated hourly maps were the basis for producing Lagrangian tracks; most tracks resulted in trapped paths which remained for long periods of time in the matrix of channels and sand-banks. A ‘tidal run’ technique was developed to calculate the length of Lagrangian tracks over one phase (ebb or flood) of the main tidal component. All tidal runs were about equal to, or shorter than, the length of the relevant channel; this indicates that tidal forcing is not effective in flushing the bay. In contrast, the observed residual currents can be an effective flushing agent if they persist for three days or longer. It is suggested that phenomena on the scale of meteorological to seasonal forcing are the effective flushing agents for Port Phillip Bay.
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Kopanev, E. V., S. V. Kryukov, and M. A. Sukhoruchkin. "Conserved currents in quantum integrable models." Theoretical and Mathematical Physics 113, no. 1 (October 1997): 1235–43. http://dx.doi.org/10.1007/bf02634011.
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Wei, Zexun, Guohong Fang, R. Dwi Susanto, Tukul Rameyo Adi, Bin Fan, Agus Setiawan, Shujiang Li, Yonggang Wang, and Xiumin Gao. "Tidal elevation, current, and energy flux in the area between the South China Sea and Java Sea." Ocean Science 12, no. 2 (April 8, 2016): 517–31. http://dx.doi.org/10.5194/os-12-517-2016.
Повний текст джерелаАнотація:
Abstract. The South China Sea (SCS) and the Java Sea (JS) are connected through the Karimata Strait, Gaspar Strait, and the southern Natuna Sea, where the tides are often used as open boundary condition for tidal simulation in the SCS or Indonesian seas. Tides, tidal currents, and tidal energy fluxes of the principle constituents K1, O1, Q1, M2, S2, and N2 at five stations in this area have been analyzed using in situ observational data. The results show that the diurnal tides are the dominant constituents in the entire study area. The constituent K1 has the largest amplitude, exceeding 50 cm, whereas the amplitudes of M2 are smaller than 5 cm at all stations. The amplitudes of S2 may exceed M2 in the Karimata and Gaspar straits. Tidal currents are mostly of rectilinear type in this area. The semi-major axes lengths of the diurnal tidal current ellipses are about 10 cm s−1, and those of the semidiurnal tidal currents are smaller than 5 cm s−1. The diurnal tidal energy flows from the SCS to the JS. The semidiurnal tidal energy flows from the SCS to the JS through the Karimata Strait and the eastern part of the southern Natuna Sea but flows in the opposite direction in the Gaspar Strait and the western part of the southern Natuna Sea. Harmonic analysis of sea level and current observation also suggest that the study area is located in the antinodal band of the diurnal tidal waves, and in the nodal band of the semidiurnal tidal waves. Comparisons show that the existing models are basically consistent with the observational results, but further improvements are necessary.
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Wei, Z. X., G. H. Fang, R. D. Susanto, T. R. Adi, B. Fan, A. Setiawan, S. J. Li, Y. G. Wang, and X. M. Gao. "Tidal elevation, current and energy flux in the area between the South China Sea and Java Sea." Ocean Science Discussions 12, no. 6 (November 20, 2015): 2831–61. http://dx.doi.org/10.5194/osd-12-2831-2015.
Повний текст джерелаАнотація:
Abstract. The South China Sea (SCS) and the Java Sea (JS) are connected through the Karimata Strait, Gaspar Strait, and the southern Natuna Sea, where the tides are often used as open boundary condition for tidal simulation in the SCS or Indonesian seas. Tides, tidal currents and tidal energy fluxes of the principle constituents K1, O1, Q1, M2, S2 and N2 at five stations in this area have been analyzed using in-situ observational data. The results show that the diurnal tides are the dominant constituents in the entire study area. The constituent K1 has the largest amplitude, exceeding 50 cm, whereas the amplitudes of M2 are smaller than 5 cm at all stations. The amplitudes of S2 may exceed M2 in Karimata and Gaspar Straits. Tidal currents are mostly of rectilinear type in this area. The major semi axis lengths of the diurnal tidal current ellipses are about 10 cm s−1, and those of the semi-diurnal tidal currents are smaller than 5 cm s−1. The diurnal tidal energy flows from the SCS to the JS. The semi-diurnal tidal energy flows from the SCS to the JS through the Karimata Strait and the eastern part of the southern Natuna Sea but flows in the opposite direction in the Gaspar Strait and the western part of the southern Natuna Sea. Harmonic analysis of sea level and current observation also suggest that the study area is located in the loop band of the diurnal tidal waves, and in the nodal band of the semi-diurnal tidal waves. Comparisons show that the existing models are basically consistent with the observational results, but further improvements are necessary.
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Ranji, Zahra, Kourosh Hejazi, Mohsen Soltanpour, and Mohammad Reza Allahyar. "INTER-COMPARISON OF RECENT TIDE MODELS FOR THE PERSIAN GULF AND OMAN SEA." Coastal Engineering Proceedings, no. 35 (June 23, 2017): 9. http://dx.doi.org/10.9753/icce.v35.currents.9.
Повний текст джерелаАнотація:
Using several series of field measurements data along Iranian coastline of the Persian Gulf and Gulf of Oman, eight different tide models have been evaluated in this study. By comparing the results in the frequency domain, it was found that the model discrepancies arise in shallow waters, having maximum error in the shallowest part of the Persian Gulf, where Pohl station is located. On the other hand, maximum error of tide models is limited to 10 cm in deeper part of the Persian Gulf, indicating that different tide models result in close outcome in deeper waters. Considering the results in the time domain, it was found that FES model, which includes more shallow water constituents, results in better tidal level predictions. FES also presents the best tidal current predictions in the area of the interest of this study.
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Shapiro, G. I. "Effect of tidal stream power generation on the region-wide circulation in a shallow sea." Ocean Science 7, no. 1 (February 24, 2011): 165–74. http://dx.doi.org/10.5194/os-7-165-2011.
Повний текст джерелаАнотація:
Abstract. This paper quantifies the backward effect on the ocean currents caused by a tidal stream farm located in the open shallow sea. Recent studies in channels with 1-D models have indicated that the power potential is not given purely by the flux of kinetic energy, as has been commonly assumed. In this study, a 3-D ocean circulation model is used to estimate (i) practically extractable energy resource at different levels of rated generation capacity of the farm, (ii) changes in the strength of currents due to energy extraction, and (iii) alterations in the pattern of residual currents and the pathways of passive tracers. As well as tidal streams, the model also takes into account the wind-driven and density-driven ocean currents. Numerical modelling has been carried out for a hypothetical tidal farm located in the Celtic Sea north of Cornwall, an area known for its high level of tidal energy. Modelling results clearly indicate that the extracted power does not grow linearly with the increase in the rated capacity of the farm. For the case study covered in this paper, a 100-fold increase in the rated generation capacity of the farm results in only 7-fold increase in extracted power. In the case of a high power farm, kinetic energy of currents is altered significantly as far as 10–20 km away from the farm. At high levels of extracted energy the currents tend to avoid flowing through the farm, an effect which is not captured with 1-D models. Residual currents are altered as far as a hundred kilometres away. The magnitude of changes in the dispersion of tracers is highly sensitive to the location. Some of the passive drifters analysed in this study experience significant variations in the end-to-start distance due to energy extraction ranging from 13% to 238% while others are practically unaffected. This study shows that both energy extraction estimates and effects on region wide circulation depend on a complex combination of factors, and the specific figures given in the paper should be generally considered as first estimates.
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Kostaschuk, R. A., J. L. Luternauer, J. V. Barrie, P. H. Leblond, and L. Werth Von Deichmann. "Sediment transport by tidal currents and implications for slope stability: Fraser River delta, British Columbia." Canadian Journal of Earth Sciences 32, no. 7 (July 1, 1995): 852–59. http://dx.doi.org/10.1139/e95-071.
Повний текст джерелаАнотація:
Tidal currents on the sandy, southern slope of Fraser River delta have generated dunes with heights of 0.5–3.5 m and lengths of 11–108 m. Dune geometry and migration measurements indicate net sediment transport to the northwest in the direction of flood tidal currents. Two current meters moored in the dune field showed greater frequencies of occurrence and higher mean current speeds in the flood direction compared with the ebb. Predictions from two bed-material load models indicate sediment transport is overwhelmingly dominated by flood currents. There is no obvious source of sand to replace sediment transported in the dune field, suggesting net erosion of the surface. A previous analysis of bathymetric data also shows recent erosion of the lower slope and overall slope steepening. These patterns of erosion could lead to slope failure and damage to coastal structures.
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Bourban, Sébastien E., Noémie D. C. Durand, Tom T. Coates, Lindsay Gill, Michael Harper, and Richardson Stephen. "MODELLING TIDAL ENERGY RESOURCE AND EXTRACTION." Coastal Engineering Proceedings 1, no. 32 (January 31, 2011): 6. http://dx.doi.org/10.9753/icce.v32.posters.6.
Повний текст джерелаАнотація:
A number of areas around the UK coast are being investigated as possible locations for tidal energy harnessing. Detailed assessment using regional hydrodynamic modelling supported by field measurements can be used to quantify the energy resource and to determine limitations in the potential development area, including those due to the interactions between waves and tides. Two case studies illustrate the techniques applied and the implications for tidal device deployment: (a) Marine Current Turbines (MCT) are planning to deploy an array of their SeaGen tidal devices off the northwest Anglesey coast, UK; and (b) THETIS Energy Ltd are planning a development off the north Northern Ireland coast in the North Channel.
The sites are characterised by moderately severe wave conditions, strong currents, and complex geomorphologic features, yielding highly variable and spatially complex, tidal range dependent current patterns. The regional hydrodynamic models (based on the TELEMAC system, an unstructured finite element solver from Electricité de France, now publicly distributed under an open source license) were calibrated against good quality field data for both sites, and captured the strong variability of the currents to a grid resolution of about 10 m over 30-day tidal cycles. Some areas were found to have strong currents on the flood tide but much weaker currents on the ebb, and vice versa and directions were not necessarily opposite. Areas with appropriate water depths, consistently good flow characteristics and, therefore, commercially attractive energy resource comprised only parts of the pre-selected sites.
Off the northwest Anglesey coast, the TELEMAC-2D hydrodynamic model was complemented with a third generation wave transformation model. The local wave conditions are strongly affected by currents, giving rise to potentially dangerous conditions for construction and maintenance operations, as well as complex forces on the energy devices. By simulating the power take-off and physical characteristics of the MCT SeaGen devices, the hydrodynamic model was used to assess the impact of individual devices on the current regime and the actual energy available from the proposed arrays taking account of wake effects (Figure 1). The extent and intensity of the wake areas were calibrated to some degree against field data obtained from the MCT Lynmouth SeaFlow deployment (installed May 2003). Wakes could extend over a significant area, requiring careful placement of the individual devices within each array to avoid reduction in power generation.
Off the north Northern Ireland coast, the TELEMAC-3D hydrodynamic model was used to produce maximum and average kinetic power density maps to identify useful site survey locations. The presence of an amphidromic point not far from the site, with virtually no tidal range yet strong currents, was correctly reproduced by the hydrodynamic model. The modelling study followed or exceeded the Assessment of Tidal Energy Resource guidance set by the European Marine Energy Centre for a full feasibility stage. In particular, comparisons with observed bed-mounted current data showed differences in maximum speed at various elevations throughout the water column within 5% or better at two of the three sites (spring tide currents).
Numerical modelling has proven to be effective and critical in investigating possible locations for tidal energy harnessing at a number of areas around the UK coast.
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Houston, James. "Nearshore and Offshore Modeling by the U.S. Army Corps of Engineers." Marine Technology Society Journal 33, no. 3 (January 1, 1999): 93–94. http://dx.doi.org/10.4031/mtsj.33.3.11.
Повний текст джерелаАнотація:
The corps of Engineers requires predictive models of hydrodynamic conditions in the nearshore and offshore to perform its civil works and military missions. To support these missions, the Corps has developed numerical models that predict tidal and wind-driven elevations and currents, directional-spectral wind-wave climatology, and groundwater movement and interaction with coastal surface waters.
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Orhan, Kadir, Roberto Mayerle, Rangaswami Narayanan, and Wahyu Pandoe. "INVESTIGATION OF THE ENERGY POTENTIAL FROM TIDAL STREAM CURRENTS IN INDONESIA." Coastal Engineering Proceedings, no. 35 (June 23, 2017): 10. http://dx.doi.org/10.9753/icce.v35.management.10.
Повний текст джерелаАнотація:
In this paper, an advanced methodology developed for the assessment of tidal stream resources is applied to several straits between Indian Ocean and inner Indonesian seas. Due to the high current velocities up to 3-4 m/s, the straits are particularly promising for the efficient generation of electric power. Tidal stream power potentials are evaluated on the basis of calibrated and validated high-resolution, three-dimensional numerical models. It was found that the straits under investigation have tremendous potential for the development of renewable energy production. Suitable locations for the installation of the turbines are identified in all the straits, and sites have been ranked based on the level of power density. Maximum power densities are observed in the Bali Strait, exceeding around 10kw/m2. Horizontal axis tidal turbines with a cut-in velocity of 1m/s are considered in the estimations. The highest total extractable power resulted equal to about 1,260MW in the Strait of Alas. Preliminary assessments showed that the power production at the straits under investigation is likely to exceed previous predictions reaching around 5,000MW.
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Erofeeva, S. Y., Laurie Padman, and Gary Egbert. "Assimilation of Ship-Mounted ADCP Data for Barotropic Tides: Application to the Ross Sea." Journal of Atmospheric and Oceanic Technology 22, no. 6 (June 1, 2005): 721–34. http://dx.doi.org/10.1175/jtech1735.1.
Повний текст джерелаАнотація:
Abstract The application of a generalized inverse approach for assimilating vessel-mounted acoustic Doppler current profiler (VM-ADCP) data into numerical solutions of barotropic tides is described. The derived estimates of tidal currents can be used to detide the VM-ADCP data and expose underlying mean circulation. The methodology is illustrated with data assimilation models of tidal currents in the Ross Sea. The prior solution, obtained by solving the nonlinear shallow-water equations by time stepping with a linear bottom friction parameterization and elevation of open boundary conditions obtained from a circum-Antarctic tide model, provides reasonably good fit to most available moored current meter data. Two inverse solutions were obtained: one assimilating moored current meter records and the other assimilating three cruises of VM-ADCP data. Fitting either the mooring time series or the VM-ADCP records leads to only small changes relative to the prior solution currents, except over the shelf break where short length scale, energetic diurnal topographic vorticity waves are present. It is shown that the dynamics embedded in the representer functions provides reasonable tidal corrections even with no prior information about forcing at open boundaries.
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Ward, Sophie L., James D. Scourse, Yusuke Yokoyama, and Simon P. Neill. "The challenges of constraining shelf sea tidal models using seabed sediment grain size as a proxy for tidal currents." Continental Shelf Research 205 (December 2020): 104165. http://dx.doi.org/10.1016/j.csr.2020.104165.
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Côté, Jessica, and Kathryn Ketteridge. "TIDAL CHANNEL GEOMETRY OF BARRIER EMBAYMENT SYSTEMS IN PUGET SOUND." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 76. http://dx.doi.org/10.9753/icce.v36.currents.76.
Повний текст джерелаАнотація:
This paper will present the first year of findings from a research project with the objective of producing empirically based models of tidal channel characteristics that can be broadly applied to design estuary restoration projects in Puget Sound. A combination of field data collection methods and desktop analysis are being utilized to calculate tidal prism, channel dimensions, marsh extent, and water surface elevations to parameterize well-functioning barrier embayments in Puget Sound. The tidal channel data will be used to conduct a regression analysis and develop hydraulic geometry scaling relationships. The goal of the study is to develop one set of regression lines for the Puget Sound basin; however, if the data collection reveals important differences between sub-basins, then two or more regressions may be developed. For example, Hood (2015) found wave exposure contributed to differences in tidal channel geometry in the major river deltas within Puget Sound. Differences in wave exposure and tide range among the sub-regions of Puget Sound could create a need for creating more than one set of scaling relationships (e.g. North Sound and South Sound).
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Murphy, Enda, Mathieu Deiber, and Sylvain Perrin. "SHEAR-DRIVEN FLUSHING OF MICRO-TIDAL MARINAS." Coastal Engineering Proceedings 1, no. 33 (December 15, 2012): 59. http://dx.doi.org/10.9753/icce.v33.currents.59.
Повний текст джерелаАнотація:
Flushing or residence times are typically used as a first step in assessing water quality in marinas, harbours and coastal basins. Recent publications have offered guidance in relation to optimal marina basin and entrance geometries to help achieve rapid renewal. However, these guidelines have been developed for the particular case where water exchange is strongly tide-driven and are not widely applicable, particularly in micro-tidal regions. Where water renewal rates are dominated by shear-driven circulation and lateral transfer of momentum at the interface between the marina and the adjacent water body (i.e. a mixing layer), there is a strong analogy to groyne fields and other cases involving flows containing quasi-stagnant peripheral areas (dead zones). A series of numerical hydrodynamic models, developed in the TELEMAC system, were used to investigate the potential for the dead zone model of water exchange to provide a
better means to guide optimization of basin and entrance geometry under such conditions. Real-world marina case
studies were used to identify any constraints affecting the practical implementation of such an approach. The numerical model results demonstrate particular conditions under which the dead zone model of water exchange can be used effectively to optimize marina basin and entrance geometry.
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Bolaños, Rodolfo, Laurent O. Amoudry, and Ken Doyle. "Effects of Instrumented Bottom Tripods on Process Measurements." Journal of Atmospheric and Oceanic Technology 28, no. 6 (June 1, 2011): 827–37. http://dx.doi.org/10.1175/2010jtecho816.1.
Повний текст джерелаАнотація:
Abstract The measurement and assessment of ocean bottom processes are important sources of information for understanding bedform evolution and sediment entrainment and for improving numerical models. Instrumented tripods have been used to investigate bottom boundary layer and sediment dynamics processes for several decades. In this paper, the effects of instrumented tripods on hydrodynamics and on the sea bed are investigated via numerical modeling and field data collected under moderate to strong tidal currents and mild surface waves. Under high currents, streamlines are modified and structure-induced vertical velocities are produced. To minimize this effect, a rotation of the three-dimensional current measurement under the frame is recommended. Acceleration of the flow under the frame is also significant (on the order of 10%–20%), which leads to an increase in bottom stress and can produce a large scour pit in energetic currents. Wave–structure interactions mainly increase turbulence near the frame. No significant wave effect has been observed near the bed, and scouring thus mostly relates to tidal currents.