Subjects -> EARTH SCIENCES (Total: 771 journals)
    - EARTH SCIENCES (527 journals)
    - GEOLOGY (94 journals)
    - GEOPHYSICS (33 journals)
    - HYDROLOGY (29 journals)
    - OCEANOGRAPHY (88 journals)

OCEANOGRAPHY (88 journals)

Showing 1 - 79 of 79 Journals sorted by number of followers
Deep Sea Research Part II: Topical Studies in Oceanography     Hybrid Journal   (Followers: 28)
Estuaries and Coasts     Hybrid Journal   (Followers: 25)
Limnology and Oceanography     Hybrid Journal   (Followers: 25)
Hydrobiology     Open Access   (Followers: 25)
Deep Sea Research Part I : Oceanographic Research Papers     Hybrid Journal   (Followers: 23)
Journal of Physical Oceanography     Hybrid Journal   (Followers: 21)
Frontiers in Marine Science     Open Access   (Followers: 20)
New Zealand Journal of Marine and Freshwater Research     Hybrid Journal   (Followers: 19)
Journal of Marine Biology & Oceanography     Hybrid Journal   (Followers: 19)
Progress in Oceanography     Hybrid Journal   (Followers: 18)
Journal of Marine Sciences     Open Access   (Followers: 18)
Coastal Engineering     Hybrid Journal   (Followers: 16)
Advances in Oceanography and Limnology     Open Access   (Followers: 16)
Maritime Studies     Open Access   (Followers: 13)
Journal of Oceanography     Hybrid Journal   (Followers: 12)
Advances in Statistical Climatology, Meteorology and Oceanography     Open Access   (Followers: 10)
Bulletin of Marine Science     Full-text available via subscription   (Followers: 9)
Atmospheric and Oceanic Science Letters     Open Access   (Followers: 9)
Fisheries Oceanography     Hybrid Journal   (Followers: 8)
International Journal of Oceanography     Open Access   (Followers: 8)
Physical Oceanography     Hybrid Journal   (Followers: 6)
Open Journal of Marine Science     Open Access   (Followers: 6)
Limnology and Oceanography: Fluids and Environments     Full-text available via subscription   (Followers: 6)
Journal of Oceanography and Marine Science     Open Access   (Followers: 6)
Oceanography : Open Access     Open Access   (Followers: 6)
Limnology and Oceanography: Methods     Hybrid Journal   (Followers: 6)
Paleoceanography and Paleoclimatology     Full-text available via subscription   (Followers: 5)
Marine Science     Open Access   (Followers: 5)
Journal of Oceanology and Limnology     Hybrid Journal   (Followers: 4)
Journal of Marine Science and Engineering     Open Access   (Followers: 4)
Ocean Yearbook Online     Hybrid Journal   (Followers: 4)
Limnology and Oceanography Letters     Open Access   (Followers: 4)
African Journal of Marine Science     Hybrid Journal   (Followers: 3)
Journal of Marine Science and Application     Hybrid Journal   (Followers: 3)
Oceanology     Hybrid Journal   (Followers: 3)
Journal of Operational Oceanography     Hybrid Journal   (Followers: 3)
Journal of Coastal Development     Open Access   (Followers: 3)
Ciencias Marinas     Open Access   (Followers: 3)
Journal of Aquatic Sciences     Full-text available via subscription   (Followers: 3)
Journal of Ocean Engineering and Marine Energy     Hybrid Journal   (Followers: 3)
Limnology and Oceanography e-Lectures     Open Access   (Followers: 3)
Development and Applications of Oceanic Engineering     Open Access   (Followers: 2)
Indian Journal of Geo-Marine Sciences     Open Access   (Followers: 2)
Regional Studies in Marine Science     Hybrid Journal   (Followers: 2)
Limnology and Oceanography: Bulletin     Hybrid Journal   (Followers: 2)
Mediterranean Marine Science     Open Access   (Followers: 2)
Annals of Marine Science     Open Access   (Followers: 2)
Annals of Limnology and Oceanography     Open Access   (Followers: 2)
Journal of Ocean University of China (English Edition)     Hybrid Journal   (Followers: 1)
Scientia Marina     Open Access   (Followers: 1)
Western Indian Ocean Journal of Marine Science     Open Access   (Followers: 1)
Marine Technology Society Journal     Full-text available via subscription   (Followers: 1)
Journal of Ocean Engineering and Science     Open Access   (Followers: 1)
Ocean Life     Open Access   (Followers: 1)
Acta Aquatica : Aquatic Sciences Journal     Open Access   (Followers: 1)
Journal of Ocean Engineering and Technology     Open Access   (Followers: 1)
Tropical Oceanography     Open Access   (Followers: 1)
Marine Systems & Ocean Technology     Hybrid Journal   (Followers: 1)
Marine Life Science & Technology     Hybrid Journal   (Followers: 1)
Coastal Engineering Proceedings : Proceedings of the International Conference on Coastal Engineering     Open Access   (Followers: 1)
Asian Journal of Fisheries and Aquatic Research     Open Access  
Thalassas : An International Journal of Marine Sciences     Hybrid Journal  
Oceans     Open Access  
Aquatic Research     Open Access  
Jurnal Kelautan Tropis     Open Access  
Depik Jurnal Ilmu-Ilmu Perairan, Pesisir dan Perikanan     Open Access  
Journal of Agricultural and Marine Sciences     Open Access  
Turkish Journal of Maritime and Marine Sciences     Open Access  
Arquivos de Ciências do Mar     Open Access  
Scientific Drilling     Open Access  
Jurnal Kelautan : Indonesian Journal of Marine Science and Technology     Open Access  
Oceanologia     Open Access  
Revista de Gestão Costeira Integrada     Open Access  
Revista Ciencias Marinas y Costeras     Open Access  
Egyptian Journal of Aquatic Research     Open Access  
China Ocean Engineering     Hybrid Journal  
Revista de Biología Marina y Oceanografía     Open Access  
Latin American Journal of Aquatic Research     Open Access  
Acta Oceanologica Sinica     Hybrid Journal  
Similar Journals
Journal Cover
Journal of Ocean Engineering and Marine Energy
Journal Prestige (SJR): 0.913
Citation Impact (citeScore): 2
Number of Followers: 3  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2198-6444 - ISSN (Online) 2198-6452
Published by Springer-Verlag Homepage  [2468 journals]
  • Iterative dynamics-based mesh discretisation for multi-scale coastal ocean
           modelling

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      Abstract: Abstract Flow in coastal waters contains multi-scale flow features that are generated by flow separation, shear-layer instabilities, bottom roughness and topographic form. Depending on the target application, the mesh design used for coastal ocean modelling needs to adequately resolve flow features pertinent to the study objectives. We investigate an iterative mesh design strategy, inspired by hydrokinetic resource assessment, that uses modelled dynamics to refine the mesh across key flow features, and a target number of elements to constrain mesh density. The method is solver-agnostic. Any quantity derived from the model output can be used to set the mesh density constraint. To illustrate and assess the method, we consider the cases of steady and transient flow past the same idealised headland, providing dynamic responses that are pertinent to multi-scale ocean modelling. This study demonstrates the capability of an iterative approach to define a mesh density that concentrates mesh resolution across areas of interest dependent on model forcing, leading to improved predictive skill. Multiple design quantities can be combined to construct the mesh density, refinement can be applied to multiple regions across the model domain, and convergence can be managed through the number of degrees of freedom set by the target number of mesh elements. To apply the method optimally, an understanding of the processes being model is required when selecting and combining the design quantities. We discuss opportunities and challenges for robustly establishing model resolution in multi-scale coastal ocean models.
      PubDate: 2024-02-23
       
  • Numerical and experimental studies on reconfiguration of flexible beam
           with point buoyancy

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      Abstract: Abstract In nature and engineering, a uniform flexible beam with point buoyancy is common, such as water lily and stem, kelp, buoy and mooring, and deep-sea flexible riser. Response to a flexible beam with point buoyancy is more complicated than that of a flexible beam. Therefore, this paper conducts theoretical numerical and water tank drag experimental research on the drag reduction problem of flexible beams with point buoyancy. First, a governing equation with point buoyancy is established. Then, an explicit iterative numerical method is proposed to solve large geometric nonlinear differential equations. Finally, numerical and experimental methods studied the drag reduction phenomenon of flexible beams with point buoyancy. The results show that the reconfiguration shape of flexible beam with point buoyancy is no longer self-similar, and there are locally bending points in beam deformations. It is found that the Vogel exponent curve fluctuates due to the non-self-similarity of the deformation shape. Moreover, as the buoyancy gets more excellent, the fluctuation range of Vogel values becomes more profound.
      PubDate: 2024-02-21
       
  • A practical wave flume layout to test reflective models without any need
           for an active absorption system

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      Abstract: Abstract Introducing a new flume layout with bottom-mounted wavemaker in the presence of fully reflective model, this paper investigates how it could be effectively utilized to eliminate different source of wave reflections. Compared with common type wave makers, bottom-mounted wavemakers could effectively eliminate wave re-reflections from the wavemaker. This paper uses analytical solution based on velocity potential to derive wave propagation for steady state excitation, where the results is verified by ANSYS CFX. It is shown that using the proposed layout it is possible, (a) to diminish the disturbing effect of re-reflection of progressive waves from the wavemaker and also to remove the possibility of resonance, and (b) to decrease the distance from the wavemaker to the absorbing beach, which results in the shorter flume length. These finding show that using the proposed layout, there is no need to use active absorbing wavemaker.
      PubDate: 2024-02-02
       
  • Experimentally calibrated finite element fatigue reliability assessment of
           an offshore platform in the Persian Gulf

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      Abstract: Abstract The Persian Gulf as one of the regions with a large number of gas and oil reservoirs hosts a considerable number of fixed offshore platforms. Corrosion and fatigue are among the main reasons for damages to these structures. Despite the importance of these structures, little is known about their fatigue reliability in this region. In this paper, we use a scaled-prototype to verify a finite element model used for the reliability assessment of this structure. Historical wave height and period data as well as data from corrosion measurements performed in this region are used to model the fatigue reliability of this platform. Fatigue reliability of this structure is assessed by first-order reliability method results of which are verified by Monte Carlo and importance sampling methods. We studied the effect of corrosion, wave height, and depth of water in the Persian Gulf on the fatigue reliability of this structure. Reliability assessment is carried out in different locations for different ages of the structure.
      PubDate: 2024-02-01
       
  • Benchmarking study of 10 MW TLB floating offshore wind turbine

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      Abstract: Abstract This paper presents a benchmarking study of four floating wind platform’ motion and dynamic tension responses to verify an innovative design with the intention of overall cost reduction of a durable, reliable, safe design. An aero-hydro-servo-elastic code is applied to benchmark a 10 MW tension leg buoy (TLB) floating wind turbine to the current leading technology types for floating offshore wind platforms, specifically spar buoy, Semi-submersible and tension leg platform (TLP) floating wind turbines. This study assumes that the platforms will deploy in the northern region of the North Sea, with a water depth of 110 m under various environmental conditions, including wind field descriptions covering uniform wind to fluctuating turbulent wind. The obtained dynamic response results showed low motion responses for the TLB platform for all design load cases. More specifically, the TLB surge and pitch motion responses are insignificant under both operational and survival conditions, allowing decreased spacing between individual wind turbines and increasing wind farms' total energy generation capacity. An additional benefit is that the wind turbine systems can be installed without significant pitch modification to the control system. The TLB platform is less complex which simplifies the construction process and has the potential for significant cost reductions.
      PubDate: 2024-02-01
       
  • Experimental and finite element analysis of the buckling response of thin
           spherical shells under hyperbaric pressure

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      Abstract: Abstract Spherical shell plays an important role in deep-water submersibles. This work reports the analysis and testing of spherical shells with an inner diameter of 150 mm and a wall thickness of 1 mm. Five spherical shell models are manufactured and subjected to hyperbaric pressure. By using a bridge gauge and ultrasonic thickness gauge, imperfection and thickness are measured respectively at various grid points. The shell is pressurized in steps until it is permanently collapsed. The pressure at which the shell collapses is compared to the pressure calculated based on a nonlinear buckling analysis. Analyses are performed considering both geometric and material nonlinearities. Results obtained from analysis and experiments are comparable. It is important to note that the initial imperfections have a significant impact on the buckling performance of the spheres.
      PubDate: 2024-02-01
       
  • Conceptual design and optimisation of a novel hybrid device for capturing
           offshore wind and wave energy

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      Abstract: Abstract The access to the offshore wind resource in the deep sea requires the development of innovative solutions which reduce the cost of energy. Novel technologies propose the hybrid combination of wind and wave energy to improve the synergy between these technologies sharing costs, such as mooring and electrical connexion. This work proposes a novel hybrid wind and wave energy system integrating a floating offshore wind turbine with three-point absorbers wave energy converters (WECs). The WECs are an integral part of the floating structure and contribute significantly to the hydrostatic and dynamic stability of the system. Their geometry is optimised considering a cylindrical, semi-cylindrical and spherical shape for the Pantelleria case study. The cylindrical shape with the largest radius and the lowest height is the optimal solution in terms of reducing structural costs and maximising the performance of the WECs. The in-house hydrostatic stability tool and the time domain model MOST are used to optimise the WECs, with a combined meta-heuristic genetic algorithm with the Kriging surrogate model and a local Nelder–Mead optimization in the final simulations. The power of the WECs is estimated with both linear and variable motor flow hydraulic PTOs to obtain a more realistic electrical power generation. Generally, the hybrid device proved to be more competitive than the floating wind turbine alone, with a LCOE reduction up to 11%. Performance of the hybrid device can be further improved when more energetic sites are considered, as the energy generated by the WECs is higher.
      PubDate: 2024-02-01
       
  • Preliminary study of the performance of a new wave energy converter

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      Abstract: Abstract The power generation challenge of any wave energy converter (WEC) depends on the efficiency of the power take-off (PTO) system. The complexity of the WEC represents a relevant factor in installation and maintenance. To increase the power generation in a direct mechanical drive PTO system the gearbox represents a necessary component, a high gear ratio affects the cost, size, complexity and maintenance of this component. This study aims to address the first analysis of power performance and operation of a new wave energy converter composed of a point absorber, a hinged arm and a direct mechanical drive PTO system. The PTO is characterized by a pulley system, the main components of PTO such as the gear ratio, the electric generator and the main pulley are analyzed in the WEC performance, a cylindrical point absorber is considered in the present study. A wave-to-wire model is developed to simulate the coupled hydro-electro-mechanical system in regular waves. The performance of the wave energy converter is analyzed using the potential linear theory but considering the viscous damping effect according to the Morison equation to avoid the overestimated responses. The new WEC shows a maximum mean power of about 28 kW. The capture width ratio shows a maximum value of 36.5% indicating that the WEC shows a better performance at small values of height and period of wave.
      PubDate: 2024-02-01
       
  • The global techno-economic potential of floating, closed-cycle ocean
           thermal energy conversion

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      Abstract: Abstract Ocean Thermal Energy Conversion (OTEC) is an emerging renewable energy technology using the ocean’s heat to produce electricity. Given its early development stage, OTEC’s economics are still uncertain and there is no global assessment of its economic potential, yet. Here, we present the model pyOTEC that designs OTEC plants for best economic performance considering the spatiotemporally specific availability and seasonality of ocean thermal energy resources. We apply pyOTEC to more than 100 regions with technically feasible sites to obtain an order-of-magnitude estimation of OTEC’s global technical and economic potential. We find that OTEC’s global technical potential of 107 PWh/year could cover 11 PWh of 2019 electricity demand. At ≥ 120 MWgross, there are OTEC plants with Levelised Cost of Electricity (LCOE) below 15 US¢(2021)/kWh in 15 regions, including China, Brazil, and Indonesia. In the short-to-medium term, however, small island developing states are OTEC’s most relevant niche. Systems below 10 MWgross could fully and cost-effectively substitute Diesel generators on islands where that is more challenging with other renewables. With the global analysis, we also corroborate that most OTEC plants return the best economic performance if designed for worst-case surface and deep-sea water temperatures, which we further back up with a sensitivity analysis. We lay out pyOTEC’s limitations and fields for development to expand and refine our findings. The model as well as key data per region are publically accessible online.
      PubDate: 2024-02-01
       
  • Review and assessment of the German tidal energy resource

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      Abstract: Abstract To mitigate climate change, a transformation of the energy sector towards a low-emission power generation is necessary. Tidal energy technology has matured in recent years and has the potential to balance Europe’s future power grid. While reviews of the tidal energy resource exist for a number of European countries, along the German North Sea coast is overlooked so far. This paper closes this gap and provides a comprehensive review and assessment of the German tidal energy resource. Germany’s North Sea coast is characterised by comparatively low current velocities and shallow waters. Using available data from the EasyGSH-DB North Sea Model, Germany’s practical tidal energy resource is estimated in a range between 66.6 and 565.8 GWh y \(^{-1}\) to, excluding the most energetic sites in the estuaries of Elbe, Weser, and Ems. A stakeholder questionnaire aimed at tidal energy technology developers has shown that it is considered important to further develop the technology towards the use in shallow water and under low current velocities.
      PubDate: 2023-12-27
       
  • Sensitivity of turbulence parameters to tidal energy converter loads in
           BEM simulations

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      Abstract: Abstract Renewable energy is playing an increasingly central role in the global energy supply due to decarbonisation and energy security aims. A vital aspect of renewable energy systems will be the predictability of the energy source, something that tidal stream energy can provide. The tidal sites suitable for energy extraction are by their nature turbulent, creating variations in the tidal energy converter (TEC) loads and affecting device durability. Developers use Blade Element Momentum (BEM) models to predict loading and improve designs of TECs. To simulate turbulence effects within these models, a synthetic flow field is generated using a combination of measured and assumed parameters. Inaccuracies in these parameters can lead to uncertainties in the simulated loads. This study investigates the sensitivity of turbulence characteristics to loads using a commercial BEM software. Variability in parameters shows a profound impact on the loads. Varying turbulence intensity resulted in a \(90\%\) change in fatigue loads for intensities ranging 2–24%. Length-scales showed a \(49\%\) decrease in loads across the range tested (5–70 m). A coherent flow field increased loads by \(45\%\) compared to a non-coherent flow. Hub-bending loads varied by \(30\%\) between different shear profiles, however varying the standard deviation profiles did not show notable effects. The results from this study emphasise the necessity for accurate turbulence parameter inputs to reduce uncertainty in device load modelling. It also highlights the importance of using realistic shear profiles as well as appropriate coherence models.
      PubDate: 2023-12-13
       
  • Tidal turbine array modelling using goal-oriented mesh adaptation

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      Abstract: Abstract To examine the accuracy and sensitivity of tidal array performance assessment by numerical techniques applying goal-oriented mesh adaptation. The goal-oriented framework is designed to give rise to adaptive meshes upon which a given diagnostic quantity of interest (QoI) can be accurately captured, whilst maintaining a low overall computational cost. We seek to improve the accuracy of the discontinuous Galerkin method applied to a depth-averaged shallow water model of a tidal energy farm, where turbines are represented using a drag parametrisation and the energy output is specified as the QoI. Two goal-oriented adaptation strategies are considered, which give rise to meshes with isotropic and anisotropic elements. We present both fixed mesh and goal-oriented adaptive mesh simulations for an established test case involving an idealised tidal turbine array positioned in a channel. With both the fixed meshes and the goal-oriented methodologies, we reproduce results from the literature which demonstrate how a staggered array configuration extracts more energy than an aligned array. We also make detailed qualitative and quantitative comparisons between the fixed mesh and adaptive outputs. The proposed goal-oriented mesh adaptation strategies are validated for the purposes of tidal energy resource assessment. Using only a tenth of the number of degrees of freedom as a high-resolution fixed mesh benchmark and lower overall runtime, they are shown to enable energy output differences smaller than 2% for a tidal array test case with aligned rows of turbines and less than 10% for a staggered array configuration.
      PubDate: 2023-12-08
       
  • Numerical analysis of a ducted water current turbine for low energetic
           flow conditions

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      Abstract: Abstract Ducted wind turbines have been investigated for decades to improve the efficiency of renewable energy production. Previous research has attempted to obtain a competitive commercial design without any relevant success. However, there is not enough evidence to disregard the potential advantages of the ducted concept for water turbines. In the ocean and marine energy industry, most prototypes are in a relatively early stage of technical development, which opens up an opportunity to re-examine alternative designs through numerical computation. This paper aims to describe the numerical performance of a unidirectional duct coupled to a 30 cm diameter horizontal axis water turbine using computational fluid dynamics. Two different approaches were used to assess the system’s performance. In the first approach, the turbine was modeled as a momentum source region according to the linear momentum actuator disk (LMAD) theory. At a flow velocity of 0.7 \({\mathrm{ms}}^{-1}\) , the ideal ducted turbine produced 1.42 times more power than its ideal bare counterpart. In the second approach, a blade geometry was designed using the standard blade element momentum (BEM) method, and the fluid interactions were simplified to a steady state by applying a moving reference frame (MRF) simulation model. For this configuration, the ducted turbine produced 1.48 times more power than its bare counterpart. An additional analysis was performed based on the power densities, and it was found that the use of a duct does not represent a real power increase in terms of the efficiency. However, several alternative advantages for the exploitation of ocean currents with low energetic flow conditions were identified and discussed.
      PubDate: 2023-12-08
       
  • Hydrodynamic coefficients of mussel dropper lines derived from large-scale
           experiments and structural dynamics

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      Abstract: Abstract The expansion of marine aquaculture production is driven by a high market demand for marine proteins and a stagnation of wild catch of fish. Bivalve farming, i.e., the cultivation of oysters, mussels and scallops, is an important part of the ongoing market dynamics and production expansion. As marine spatial planning is considering various use purposes, available space for near-shore aquaculture is already becoming scarce; this has fueled research and development initiatives to enable production installations further offshore. The highly energetic conditions at more exposed offshore marine sites lead to increased loads on aquaculture systems and their components and it is still not sufficiently understood how the load transfer from oceanic environmental conditions onto shellfish-encrusted surfaces attached to elastic ropes may be appropriately quantified. This study data gathered large-scale data sets in a wave tank facility, which are used to validate a novel, numerical model, building on the dynamics of rope structures which allows for the determination of the hydrodynamic loads transferred to the dropper lines. The forces and hydrodynamic parameters are measured and numerically analyzed. Based on the results, drag and inertia coefficients are determined. A drag coefficient of \(C_\textrm{D} = 1.1\) and an inertia coefficient of \(C_\textrm{M} = 1.7\) are recommended to model shellfish-encrusted dropper lines exposed to oscillatory flows with KC  \(=\)  40–90. The numerical model for the determination of wave-induced forces on mussel dropper lines is developed and validated using the experimental data. It employs a modified Morison equation, which takes into account the displacement of the mussel dropper line. The influence of varying aquaculture-related parameters is discussed by applying the numerical model. Based on the gathered insights, recommendations can be given from an engineering point of view concerning the optimal placement of mussel aquaculture within the water column.
      PubDate: 2023-11-28
      DOI: 10.1007/s40722-023-00306-w
       
  • Future predictions of wave and response of multiple floating bodies based
           on the Kalman filter algorithm

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      Abstract: Abstract The present work explores the possibility of predicting future waves by extending the Kalman filter algorithm by incorporating the spatial distance between two points. Experimental data at 2D tank are used to validate the effectiveness of the proposed method. When causality limitation is fulfilled, it is found that 3–8 s or several cycles of waves ahead can be predicted in model scale, depending on the distance between the two points. If a scaling of 1/100 is adopted, this means 30–80 s waves ahead can be estimated. The longer the distance, the longer future predictable time will be. Response predictions using wave prediction data are also investigated. The results for the response prediction also exhibits high accuracy, with even higher predictable future time (80–120 s ahead given 1/100 scale ratio) compared to its associated predictable future time of waves.
      PubDate: 2023-11-26
      DOI: 10.1007/s40722-023-00304-y
       
  • Experimental comparison of passive adaptive blade pitch control strategies
           for an axial-flow current turbine

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      Abstract: Abstract Two passive blade pitch control strategies for an axial-flow current turbine were developed and tested experimentally in a recirculating flume. The goal of the control is to regulate mechanical power, while limiting rotor loads, when flow conditions exceed the rated condition. Both strategies use blades fabricated with unidirectional carbon fiber oriented off-axis, such that the blades twist passively as they deflect in response to loading. One control strategy combines passive adaptive blades with overspeed control (operating at a rotational speed above the tip-speed ratio corresponding to peak efficiency) while the other combines passive adaptive blades with active pitch control (actuating blade pitch using motors at the blade root). Both strategies were implemented with a 0.45-m diameter turbine in linearly increasing inflow from 0.7 to 0.8 m/s and compared to control strategies using rigid, aluminum blades under the same flow conditions. The passive adaptive blades combined with active pitch control saw no improvement in steady-state load reductions relative to rigid blades used with active pitch control. However, the passive adaptive blades combined with overspeed control successfully produced constant torque with an only 12% increase in thrust, relative to the rated flow condition. The flow confinement likely enhanced the relative benefit of passive adaptive blades compared to speed control strategies with rigid blades. Overall, results indicate that passive adaptive blades combined with overspeed control can be an effective strategy in currents above the rated flow speed, removing the need for an active pitch mechanism in some applications. In addition to measuring turbine loads, deflection and twist of the passive adaptive blades during experimental testing were observed using a high-speed camera to support our understanding of the bend–twist behavior during turbine operation over a range of flow speeds, rotation rates, and preset pitch angles.
      PubDate: 2023-11-25
      DOI: 10.1007/s40722-023-00302-0
       
  • Wave energy conversion using a small tubular free-floating device

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      Abstract: Abstract Wave energy devices traditionally tend to be large, as their sizes are often determined by power conversion targets and their operating wave climates. Here we examine a size-constrained device designed to fit within narrow tubes, and using well-known analysis techniques show that converted power amounts may be large enough to meet or exceed the needs of instrumentation to serve a majority of oceanographic and defense ocean measurement needs. The device examined in this paper is designed to fit within, and to be deployed from, torpedo tubes or other equivalently sized cylindrical containers. Examined in this paper is a traditional tubular oscillating water column device, and particular interest here is in designs that lead to optimization of power converted in anticipated wave climates. A two-step design procedure is investigated here, wherein a more approximate two-degree-of-freedom model is first used to identify relative dimensions (of device elements) that optimize power conversion from relative oscillations between the device elements. A more rigorous mathematical model based on the hydrodynamics of oscillating pressure distributions within solid oscillators is then used to provide the hydrodynamic coefficients, forces, and flow rates for the device. These results are next used together with a power take-off model, to provide a quick but rigorous way to estimate the energy conversion performance of the device in various wave climates. A power take-off based on a self-rectifying turbine system is used, and its representative conductance and susceptance values are derived for a chosen geometry and configuration. Calculations are carried out to illustrate the design procedure, and converted power values exceeding ten watts are noted in wind-sea like conditions. Further, performance comparisons with solar panels in Arctic latitudes indicate that such designs may yield considerably better energy conversion during seasons of low insolation. These devices could be designed to convert enough power to perform designated ocean measurement operations while storing any excess energy to support vehicle recharging operations.
      PubDate: 2023-11-13
      DOI: 10.1007/s40722-023-00299-6
       
  • A prediction tool for maintenance costs estimation during the design
           process of a ship engine room

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      Abstract: Abstract When dealing with maintenance in ships engine room, the space available around machinery and systems (clearance) plays an important role and may significantly affect the cost of the maintenance intervention. In a first part of a current research study Gualeni et al. (Ship Technol Res, 10.1080/09377255.2021.2020949, 2022), a quantitative relation between the maintenance costs increment due to the clearance reduction is determined, using a Bayesian approach to General Linear Model (GLM), with reference to a single item/component of a larger system Sánchez-Herguedas et al. (Reliability Eng Syst Saf 207: 107394, 2021). This paper represents the second part of the activity and it enforces a systemic view over the whole machinery or system Sanders and Klein (Proc Comput Sci 8:413–419, 2012). The aim is to identify not only the relation between maintenance costs and clearance reduction, but also how the clearance reductions of the single components/items interact and affect the whole system/machinery accessibility and maintainability, meant as relevant emerging properties. The system emerging properties are investigated through the design and application of a Hidden Markov Model Salvatier et al. (Peer J Comput Sci 2: e55, 2016); i.e., the system is modeled by a Markov process with unobservable states. The sequence of states is the maintainability of the system (which incorporates each one of the single components) while the evidence is the increase in cost of maintenance related to the space reduction. By predicting a sequence of states, it is therefore possible to predict the interactions between the system components clearances and determine how the emerging maintainability property is affected by the engine room design.
      PubDate: 2023-11-01
      DOI: 10.1007/s40722-023-00288-9
       
  • Theoretical and CFD modelling of single and slug oil, water and gas flows
           in a deepwater rigid jumper

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      Abstract: Abstract In the present work, computational fluid dynamics modelling (CFD) of single-phase flow (oil, water, gas) and two-phase flows (oil/water, oil/gas, gas/oil) was performed, to study the behaviour of these types of flow in a rigid jumper employed for the production of oil and gas in deepwater hydrocarbons fields. The jumper conducts the produced fluids from a subsea tree to a PLET. The modelled fluids were extracted from a drill stem testing study, corresponding to multiphase flow of water, gas and oil. In the present modelling strategy, the jumper and was considered thermally insulated to avoid heat transfer between internal fluids and external environmental conditions, and the end connectors of the jumpers were also considered insulated along with tree and PLET connection points. The flow patterns, pressure drops, slugs and flow velocity variations through the jumper were obtained from CFD simulations to visualize and study their behaviour in the jumper during the flow. The CFD pressure results were compared with theoretical calculations with good agreement, producing fast results. However, CFD results allowed to visualize internal flow behaviour, calculate the time needed by each flow condition from jumper inlet to jumper outlet, flow patterns, pressure drops, etc. The methodology can also be used to estimate the production rate of the different modelled flows, to identify critical flow conditions inside a rigid jumper and select the appropriate jumper internal diameter.
      PubDate: 2023-11-01
      DOI: 10.1007/s40722-023-00286-x
       
  • Effects of turbine damping and wave conditions on OWC performances for
           optimal wave energy conversion

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      Abstract: Abstract The oscillating water column (OWC) devices constitute the most widely used systems for the wave energy conversion. Optimizing the performances of such devices mainly composed with a bidirectional air turbine and a water–air chamber still remains of great interest. The present investigations focus on the numerical analysis of an OWC system, the air turbine damping, and on its coupling with the OWC chamber. A validated 2D RANS-VoF numerical model was implemented to determine the optimum induced damping of the OWC device in case of an impulse turbine. The model is based on the concept of the Numerical Wave Tank (NWT). In the present model, the turbine quadratic behavior was simulated with an orifice. Simulations have been conducted in typical cases located on the central zone of the Moroccan Atlantic coast. All the simulated cases are of intermediate water waves which are in compliance with the use of the Stokes’ second-order wave generation. The pneumatic power corresponding to the various values of turbine-induced damping is computed, and the optimum damping accounting for the wave climate variability is identified. It was found that the damping induced by the air turbine is the factor that influence most the OWC chamber efficiency, followed by the climate conditions.
      PubDate: 2023-07-21
      DOI: 10.1007/s40722-023-00293-y
       
 
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  Subjects -> EARTH SCIENCES (Total: 771 journals)
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Deep Sea Research Part II: Topical Studies in Oceanography     Hybrid Journal   (Followers: 28)
Estuaries and Coasts     Hybrid Journal   (Followers: 25)
Limnology and Oceanography     Hybrid Journal   (Followers: 25)
Hydrobiology     Open Access   (Followers: 25)
Deep Sea Research Part I : Oceanographic Research Papers     Hybrid Journal   (Followers: 23)
Journal of Physical Oceanography     Hybrid Journal   (Followers: 21)
Frontiers in Marine Science     Open Access   (Followers: 20)
New Zealand Journal of Marine and Freshwater Research     Hybrid Journal   (Followers: 19)
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Progress in Oceanography     Hybrid Journal   (Followers: 18)
Journal of Marine Sciences     Open Access   (Followers: 18)
Coastal Engineering     Hybrid Journal   (Followers: 16)
Advances in Oceanography and Limnology     Open Access   (Followers: 16)
Maritime Studies     Open Access   (Followers: 13)
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Advances in Statistical Climatology, Meteorology and Oceanography     Open Access   (Followers: 10)
Bulletin of Marine Science     Full-text available via subscription   (Followers: 9)
Atmospheric and Oceanic Science Letters     Open Access   (Followers: 9)
Fisheries Oceanography     Hybrid Journal   (Followers: 8)
International Journal of Oceanography     Open Access   (Followers: 8)
Physical Oceanography     Hybrid Journal   (Followers: 6)
Open Journal of Marine Science     Open Access   (Followers: 6)
Limnology and Oceanography: Fluids and Environments     Full-text available via subscription   (Followers: 6)
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Development and Applications of Oceanic Engineering     Open Access   (Followers: 2)
Indian Journal of Geo-Marine Sciences     Open Access   (Followers: 2)
Regional Studies in Marine Science     Hybrid Journal   (Followers: 2)
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Scientia Marina     Open Access   (Followers: 1)
Western Indian Ocean Journal of Marine Science     Open Access   (Followers: 1)
Marine Technology Society Journal     Full-text available via subscription   (Followers: 1)
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Ocean Life     Open Access   (Followers: 1)
Acta Aquatica : Aquatic Sciences Journal     Open Access   (Followers: 1)
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Tropical Oceanography     Open Access   (Followers: 1)
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Coastal Engineering Proceedings : Proceedings of the International Conference on Coastal Engineering     Open Access   (Followers: 1)
Asian Journal of Fisheries and Aquatic Research     Open Access  
Thalassas : An International Journal of Marine Sciences     Hybrid Journal  
Oceans     Open Access  
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Jurnal Kelautan Tropis     Open Access  
Depik Jurnal Ilmu-Ilmu Perairan, Pesisir dan Perikanan     Open Access  
Journal of Agricultural and Marine Sciences     Open Access  
Turkish Journal of Maritime and Marine Sciences     Open Access  
Arquivos de Ciências do Mar     Open Access  
Scientific Drilling     Open Access  
Jurnal Kelautan : Indonesian Journal of Marine Science and Technology     Open Access  
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Revista de Gestão Costeira Integrada     Open Access  
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