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Ocean Engineering
Pergamon Press
Ocean Engineering

Pergamon Press

不定期

0029-8018

Ocean Engineering/Journal Ocean EngineeringSCIEIISTP
正式出版
收录年代

    Numerical investigations of ship hydroelasticity of a 20,000 TEU containership based on CFD-MBD method

    Zhang W.Wang J.Wan D.Guo H....
    1.1-1.15页
    查看更多>>摘要：© 2024 Elsevier LtdIn this paper， a fully coupled fluid-structure interaction method is proposed to study ship hydroelastic responses。 A two-way coupling of CFD (Computational Fluid Dynamics) and MBD (Multi-Body Dynamics) solvers is applied to the numerical study of a 20，000 TEU containership。 The flow field is solved using the RANS equations in OpenFOAM， while the structural dynamic responses are calculated using a beam model in MBDyn。 Another open-source library， preCICE， is utilized for data exchange between the fluid and structural components in the coupling algorithm。 The numerical results for the Response Amplitude Operators (RAOs) of ship motion and vertical bending moment (VBM) at midship are validated against experimental data under different wavelengths。 Additionally， the hydroelastic responses are analyzed。 The longitudinal distribution trends of the VBM under different wavelengths show a consistent pattern， with maximum hogging and sagging values occurring around the midship area。 The maximum VBM responses are observed under conditions of λ/L = 0。8 and λ/L = 0。9， exhibiting significant high-frequency harmonic components。 The comparison between numerical predictions of VBM for elastic and rigid ship body structures reveals a significant underestimation of VBM for rigid ships， even in relatively low sea conditions。 This finding demonstrates the necessity of considering elasticity in the calculations of hydroelastic responses for ultra-large container ships。
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    • Elsevier

    Experimental study and uncertainty analysis on added resistance and pressure distribution of KVLCC2 in regular short waves

    Zhang Z.Ma N.Shi Q.Wen Y....
    1.1-1.19页
    查看更多>>摘要：© 2024 Elsevier LtdThis study investigates the added resistance experienced by the KVLCC2 vessel in extremely short wave conditions， addressing the challenges posed by the increasing size of modern ships， which results in shorter relative wavelengths in actual sea conditions。 Using a 4。5-m-long seakeeping model in a 280-m-long towing tank， experiments were conducted to analyze the added resistance in head waves with a wavelength ratio below 0。3。 The effects of wave steepness and local pressure distribution， particularly in the bow region， were also examined on the KVLCC2 standard model for the first time。 The reasons for the reduction in wave added resistance coefficient with increasing wave steepness were discussed， and three distinct distribution patterns are analyzed according to the physical mechanism of wave added resistance。 Additionally， two distinct movement restriction systems were developed， allowing for a comparative evaluation between surge-fixed and surge-free conditions。 A comprehensive uncertainty analysis， following ITTC guidelines， reveals that Type A uncertainty of measuring added resistance and Type B uncertainty related to wave amplitude， are two dominant factors in the combined uncertainty。 These findings improve the understanding of the physical mechanisms behind added resistance in extremely short waves， which is critical given the ongoing trend of vessel enlargement in the maritime industry。
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    • Elsevier

    ANN-based surrogate model for the structural evaluation of jacket support structures for offshore wind turbines

    Quevedo-Reina R.Alamo G.M.Aznarez J.J.
    1.1-1.11页
    查看更多>>摘要：© 2024 Elsevier LtdThe expansion of offshore wind farms， driven by better offshore wind conditions and fewer spatial limitations， has promoted the growth of this technology。 This study focuses on the design of jacket support structures for Offshore Wind Turbines， which are suitable for deeper waters。 However， the structural analysis required for designing these structures is computationally intensive due to multiple load cases and numerous checks。 To reduce this computational cost， artificial-neural-network-based surrogate models capable of estimating the feasibility of a jacket structure acting as the support structure for any given wind turbine at a specific site are developed。 A synthetic dataset generated through random sampling and evaluated by a structural model is utilized for training and testing the models。 Two kind of models are compared: one is trained to estimate global feasibility， while the other estimates compliance with each of the structural partial requirements。 Also， several assembly methods are proposed and compared。 The best-performing model shows great classification metrics， with a Matthews Correlation Coefficient of 0。674， enabling an initial assessment of the structural feasibility。 The low computational cost of artificial neural networks compared to structural models makes this surrogate model useful for accelerating otherwise prohibitive parametric studies or optimization processes。
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    • Elsevier

    Assessing long short-term memory network significant wave height forecast efficacy in the Caribbean Sea and Northwestern Atlantic Ocean

    Bethel B.J.Dong C.Sun W.Zhou S....
    1.1-1.14页
    查看更多>>摘要：© 2024Precise wave forecasts are crucial， but few studies have directly tested artificial intelligence forecast efficacies in different wave regimes。 Using ten years of buoy observations and Simulating WAves Nearshore (SWAN) simulations， the wave climates of the Caribbean Sea (CS) and Northwestern Atlantic Ocean (NWAO) are studied from 2010 to 2019。 SWAN simulations are used to replace fragmentary buoy observations and then forecasting using the Long Short-Term Memory (LSTM) network is initiated on six sites throughout the CS and NWAO。 Although expected， results illustrate that regardless of test site， LSTM forecasts were highly accurate， reaching correlation values of >0。8， root-mean-square errors <0。4 m， and mean average percentage errors of <14% up to 12-hr forecast horizons。 Location-specific geographic and metocean attributes led to divergent forecast outcomes between test sites。 Forecast correlations were higher near， but not directly under the Caribbean Low-Level Jet， leading to the best forecast results in the western CS， followed by the central CS， and was poorest in the NWAO。 It was conclusively determined NWAO and CS wave fields are sufficiently different to ensure that forecasting using information from either subregion on its counterpart would lead to low correlations and unacceptably high levels of error。
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    A probabilistic framework for assessing helicopter landing conditions within the ship air-wake

    Setiawan H.Zheng K.KevinMonty J.P....
    1.1-1.8页
    查看更多>>摘要：© 2024 Elsevier LtdParticle Image Velocimetry (PIV) measurements were performed in a wind-wave facility to characterise the ship air-wake on the landing deck (LD) of a stationary NATO-GD model。 To our knowledge， this is the first laboratory ship air-wake experiment in a naturally-developed boundary layer over a water surface。 This study builds on our previous wind tunnel tests over a solid floor (Setiawan et al。 2022， Ocean Engineering， vol。 260， 111931)。 The results indicate that the air-wake statistical characteristics are comparable to the wind tunnel data， with the mean flow and turbulence kinetic energy only differing by 5% and 2%， respectively， from the flat-plate baseline flow。 We further developed a new probabilistic method to estimate the “landing risk” percentage based on the likelihood of extreme turbulence events。 Although the exercise was performed using the local vertical wind fluctuations 〈σwn〉LD employing a threshold specified for civil aviation， the approach can be adapted for other metrics or can employ a more suitable limit for the Navy context。 In essence， we mapped the fractional time (out of the total PIV snapshots) when the 〈σwn〉LD exceeded the selected threshold。 Having shown Reynolds number independence， we scaled up the velocity data in order to emulate a set of higher reference velocities。 It is shown there is a non-linear increase in the “landing risk” percentage with increasing reference velocity (wind speed)， and the various inflow conditions affect landing risk。
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    Calculation method of flow drag around a pile in soft soil considering Bingham fluid properties and analysis of single pile response

    Wu M.Zheng L.Deng T.Zheng J....
    1.1-1.9页
    查看更多>>摘要：© 2024 Elsevier LtdThe lateral displacement of deep soft soil caused by large-area heap loading is a common issue in engineering practice， which affects the stability of neighboring pile foundations。 This study investigates the calculation of thrust force exerted by the flow of soft soil around piles and its impact on pile foundations。 The surrounding soft soil is considered a Bingham fluid。 An analytical formula for single pile flow drag during the internal slip of deep soft soil is derived based on fluid mechanics theory and the fluid characteristics of the Bingham fluid。 The traditional cantilever pile approach is modified by assuming a rectangular distribution of flow drag along the pile body and using the matrix transfer method。 The response of a single pile body under field heap loading conditions is then analyzed， and the results are compared with the calculation results of the traditional soil pressure method and field-measured data to validate the proposed calculation method for flow drag around a pile in soft soil。 Finally， a parametric study is conducted to analyze the effects of the relative flow velocity and dynamic viscous coefficient of soft soil on flow drag。
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    Digital twin development towards integration into blue economy: A bibliometric analysis

    Bhati M.Goerlandt F.Pelot R.
    1.1-1.22页
    查看更多>>摘要：© 2024 The AuthorsDigital Twin (DT) technology plays a crucial role in the modernization and optimization of numerous industrial sectors。 The blue economy encompasses established sectors such as marine energy systems， shipbuilding and operation， aquaculture and fisheries， and emerging areas including coastal protection and deep-sea mining。 Many of these sectors are crucial for attaining Sustainable Development Goals (SDGs)， especially pertaining to climate action and marine biodiversity。 The integration of DT technologies within the blue economy can offer added value by enhancing operational efficiency， improving risk management， and fostering sustainable practices。 This paper uses bibliometric research methods to provide a state-of-the-art overview of this research area。 Insights are obtained through several bibliometric indicators， including publication trends， country-based distribution patterns of scholarly communications， and research impact through citation analysis。 Keyword co-occurrence analysis is carried out to identify key research themes within the main blue economy sectors。 This analysis will enable the research community to understand the key research themes， trends， major research hotspots， and influential works to provides a foundation for innovation， efficiency， and sustainability， benefiting researchers and industry actors。 Additionally， it provides policy makers with evidence-based insights crucial for crafting informed policies that promote sustainable development within the blue economy。
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    Physical insight into transient hydrodynamics and corresponding flow structures of a pitching hydrofoil via boundary vorticity dynamics

    Hao H.-Y.Yuan R.Wu Q.Huang B....
    1.1-1.11页
    查看更多>>摘要：© 2024The objective of this study is to investigate the hydrodynamic forces acting on a pitching Clark-Y hydrofoil， with a focus on dynamic flow structures such as boundary-layer separation and vortex evolution， which are driven by the interaction between tangential pressure gradients and on-wall vorticity generation。 Numerical simulations were conducted using the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations at a Reynolds number of 5 × 104。 Proper Orthogonal Decomposition (POD) was applied to identify the energetic flow modes， while Boundary Vorticity Flux (BVF)-based lift decomposition was further employed to explore the dominant lift contribution。 The results showed that the time-space evolution of the laminar separation bubble (LSB) and trailing-edge vortices (TEVs) experienced a notable delay in formation during the upstroke as the pitching rate increased。 The fluctuating LSB and TEV were extracted as the primary energetic modes。 The dominant lift contributions were found to arise from pressure-gradient-induced vorticity generation on the hydrofoil surface。 Especially， substantial lift fluctuations were traced to concentrated σp peaks downstream of the LSB and alternating peaks at the trailing edge。 Moreover， the delayed onset of LSB bursting and an earlier initiation of trailing-edge separation was attributed to variations in the integral magnitude of σp in the leading and trailing regions。 These insights have direct implications for the design and control of hydrofoil-based systems in marine applications， like underwater control surfaces and hydrokinetic turbines， aiding in the development of strategies to enhance stability and efficiency under dynamic flow conditions。
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    Boundary-layer transition on a shallowly submerged vehicle

    Liu B.Yin Z.Zhang X.An Q....
    1.1-1.11页
    查看更多>>摘要：© 2024 Elsevier LtdAs the underwater vehicle travels beneath the free surface， the surface gravity waves are generated， which may have a significant effect on the boundary-layer transition。 The boundary-layer transitions on a shallowly submerged vehicle are investigated by coupling the transition model， wave system model， and volume of fluid model。 The numerical method is validated through the experimental data and theory。 It is found that the free surface has a significant influence on the boundary-layer transition of the upper surface， whereas no such influence is observed on the transition of the lower surface。 On the upper surface， the wave system of the free surface results in a fuller velocity profile and a more extended region of the laminar flow， which causes a delay in the boundary-layer transition。 The underlying mechanism of the transition delay phenomenon on a shallowly submerged vehicle is discussed。 It is observed that the region of the favorable pressure gradient generated by the interaction between the bow and aft shoulder waves of the free surface becomes larger。 Furthermore， as the submergence depth increases， the transition delay effect weakens rapidly， which is closely associated with the sharp reduction in amplitude of the free surface wave and in favorable pressure gradient。
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    • Elsevier

    Structural parameters analysis and optimization design study of double-pier linkage-type anticollision device

    Cai Y.Ma B.Wang F.Fan Y....
    1.1-1.16页
    查看更多>>摘要：© 2024 Elsevier LtdThe double-pier linkage-type anticollision device (DPLT-AD) is a novel protective device for double-bridge systems， allowing two piers to jointly resist ship collisions， thereby enhancing each pier's collision resistance。 To distribute the ship collision force more evenly to the two piers， this paper conducts an optimization study on the DPLT-AD。 Firstly， a novel simplified finite element (FE) model of the viscoelastic energy-absorption ring (VEAR， the crucial force-transmitting component in the DPLT-AD) was proposed and proven to effectively capture the actual mechanical behavior of the VEAR。 The modeling approach in this paper was validated through full-scale ship collision tests。 Subsequently， the effects of the VEAR's quantity and stiffness and the outer steel box's plate thickness on the force transmission performance of DPLT-AD were discussed。 Results show that the synergistic force effect between the double piers was highly sensitive to the quantity and stiffness of the VEARs within the triangular area and the plate thickness of the entire outer steel box。 Based on parameters analysis， a multi-objective optimization design method for the DPLT-AD was proposed using the BBD response surface method and the NSGA-II algorithm。 After optimizing the DPLT-AD， the synergistic force effect between the double piers under high-velocity collisions from large-tonnage ships was significantly enhanced， and the peak ship collision force was also reduced， greatly improving the safety of each bridge。 This study can provide a scientific and rational solution to address the issue of large-tonnage ships colliding with double-bridge systems。
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    • Elsevier