Hydrodynamics of Offshore Structures

A special issue of Journal of Marine Science and Engineering (ISSN 2077-1312). This special issue belongs to the section "Ocean Engineering".

Deadline for manuscript submissions: closed (15 April 2023) | Viewed by 15911

Image courtesy of Dr. Harrif Santo

Special Issue Editors


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Guest Editor
Technology Centre for Offshore and Marine, Singapore (TCOMS), Singapore 118411, Singapore
Interests: extreme waves; fluid–structure interactions; digital twins; cyber-physical systems
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Institute for Ocean Engineering, Tsinghua University, Shenzhen 518055, China
Interests: offshore hydrodynamics; dynamics of floating systems; wave-structure interaction; marine & offshore operation

Special Issue Information

Dear Colleagues,

The marine and offshore (M&O) industry has been undergoing an active transformation toward digitalization to enhance operational efficiency, reduce expenditures, and improve productivity. Concepts and solutions of digital twins are becoming more common. In parallel, sustainability calls for an energy transition from fossil fuels to cleaner energy sources, such as offshore renewable energy. Whether this is to improve the digitalization solution or to produce a more efficient energy-harnessing system, a profound understanding of the hydrodynamics of the structures—how they interact with the operating environment and how they behave as a coupled system—is important.

This Special Issue on “Hydrodynamics of Offshore Structures” will touch on the latest developments and findings that aim to deepen our understanding, such as those obtained from field measurements, physical wave tank tests, numerical simulations ranging from high fidelity to reduced-order models, and data-driven models for real-time predictions. The following topics will be covered:

  • Environment (wind, waves and current);
  • Bottom-founded structures (such as monopiles, jackets, compliant towers, and jack-ups);
  • Floating structures (such as ships, floaters, spars, semi-subs and TLPs);
  • Coupled multi-body systems (such as floating PVs, offshore aquaculture systems);
  • Novel structures (such as wave energy converters).

We look forward to receiving your contribution.

Dr. Harrif Santo
Dr. Binbin Li
Guest Editors


Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Journal of Marine Science and Engineering is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Free-surface wave hydrodynamics
  • Offshore hydrodynamics
  • Wave–structure interactions
  • Fluid–structure interactions
  • Real-time predictions
  • Digital twin

Published Papers (8 papers)

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Research

24 pages, 4987 KiB  
Article
A Coupled Hydrodynamic–Structural Model for Flexible Interconnected Multiple Floating Bodies
by Mingsheng Chen, Mingjun Ouyang, Hongrui Guo, Meiyan Zou and Chi Zhang
J. Mar. Sci. Eng. 2023, 11(4), 813; https://doi.org/10.3390/jmse11040813 - 11 Apr 2023
Cited by 13 | Viewed by 1733
Abstract
Evaluating the structural safety and seakeeping performance of very large floating structures (VLFS) using the rigid module flexible connector (RMFC) method remains challenging due to the complexity of the coupled hydrodynamic–structural responses in this system. In this study, a coupled hydrodynamic–structural frequency–time domain [...] Read more.
Evaluating the structural safety and seakeeping performance of very large floating structures (VLFS) using the rigid module flexible connector (RMFC) method remains challenging due to the complexity of the coupled hydrodynamic–structural responses in this system. In this study, a coupled hydrodynamic–structural frequency–time domain model is developed based on the RMFC method employing the planar Euler–Bernoulli beam elements to investigate the dynamic responses of multi-module floating systems. To reveal the dynamic characteristics of the systems, the coupled hydrodynamic–structural responses are investigated using a frequency–time-domain numerical model with viscous correction, in which the mass and stiffness attributes of connectors are incorporated into the system. Given the effects of hydrodynamic interaction, consideration is given to the case of three modular boxes connected by flexible beams aligned in series in shallow water to validate the present model. Higher efficiency and accuracy can be found in the system using viscous correction in potential flow theory and introducing state–space model to replace the convolution terms in the Cummins equation for the time domain. Moreover, this model can be extended to a considerable number of floating modules, which provides possibilities to analyze N-module floating systems. Full article
(This article belongs to the Special Issue Hydrodynamics of Offshore Structures)
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29 pages, 7484 KiB  
Article
Dynamic Analysis of Full-Circle Swinging Hoisting Operation of a Large Revolving Offshore Crane Vessel under Different Wave Directions
by Dapeng Zhang, Bowen Zhao, Keqiang Zhu and Haoyu Jiang
J. Mar. Sci. Eng. 2023, 11(1), 197; https://doi.org/10.3390/jmse11010197 - 12 Jan 2023
Cited by 3 | Viewed by 1707
Abstract
Waves have an important influence on the motion performances of offshore crane vessels. The floating crane vessel in waves gives rise to the motion of the lifted object which is connected to the hoisting wire. Based on the geometric parameters of a revolving [...] Read more.
Waves have an important influence on the motion performances of offshore crane vessels. The floating crane vessel in waves gives rise to the motion of the lifted object which is connected to the hoisting wire. Based on the geometric parameters of a revolving offshore crane vessel, combined with the specific process of the floating crane vessel at work, a model of the offshore crane vessel under full-circle swing hoisting has been established by OrcaFlex. With the change in wave direction, the dynamic response of the system is made and the impact force between the support vessel and the hanging object and the tension of the crane wire under different wave directions is obtained. At the same time, the minimum impact forces between the support vessel and the hanging object and the tension of the crane wire and their wave directions are obtained. According to the calculated result, the optimal design of the full-circle swing hoisting operation of large revolving offshore crane vessel has been determined. Full article
(This article belongs to the Special Issue Hydrodynamics of Offshore Structures)
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16 pages, 5396 KiB  
Article
Combining Reduced-Order Stick Model with Full-Order Finite Element Model for Efficient Analysis of Self-Elevating Units
by Chi Zhang, Shanli Zhang, Harrif Santo, Minbo Cai, Modi Yu and Michael Si
J. Mar. Sci. Eng. 2023, 11(1), 119; https://doi.org/10.3390/jmse11010119 - 5 Jan 2023
Cited by 3 | Viewed by 1157
Abstract
Reduced-order stick models are frequently employed to obtain dynamic amplification factors of self-elevating units (SEU), while the full-order finite element (FE) models are used for quasi-static analyses. This paper develops an efficient framework to create structural digital twins for SEUs by combining both [...] Read more.
Reduced-order stick models are frequently employed to obtain dynamic amplification factors of self-elevating units (SEU), while the full-order finite element (FE) models are used for quasi-static analyses. This paper develops an efficient framework to create structural digital twins for SEUs by combining both stick models and full-order FE models. A stick model and a detailed FE model of an in-house developed generic SEU are established, respectively, following the standard industry guideline. Dynamic analyses are performed for the stick model based on the modal superposition method. Assuming that the stick model contains the key dynamic characteristics of the full-order FE model, the modal participation factors are multiplied by the corresponding mode shapes of the full FE model to derive the global dynamic responses of the entire SEU. The derived nodal displacements are imposed on the full-order model to obtain the member stresses. The global responses and member stresses are benchmarked with the results from a direct full-order dynamic FE analysis for various environmental conditions. The presented framework is found to significantly increase the efficiency of the simulation while retaining a similar accuracy, and it forms a critical step for the ongoing development of digital twins of fixed offshore structures. Full article
(This article belongs to the Special Issue Hydrodynamics of Offshore Structures)
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16 pages, 4998 KiB  
Article
Design of a Full-Ocean-Depth Macroorganism Pressure-Retaining Sampler and Fluid Simulation of the Sampling Process
by Guangping Liu, Yongping Jin, Youduo Peng, Deshun Liu and Buyan Wan
J. Mar. Sci. Eng. 2022, 10(12), 2007; https://doi.org/10.3390/jmse10122007 - 15 Dec 2022
Cited by 1 | Viewed by 1354
Abstract
Hadal seafloor organisms live under ultra-high pressure, in low temperatures, and other environments for a long time, which puts higher requirements on the structural design of deep-sea biological samplers. In this paper, we present a full-ocean-depth hydraulic suction macroorganism pressure-retaining sampling method, which [...] Read more.
Hadal seafloor organisms live under ultra-high pressure, in low temperatures, and other environments for a long time, which puts higher requirements on the structural design of deep-sea biological samplers. In this paper, we present a full-ocean-depth hydraulic suction macroorganism pressure-retaining sampling method, which actively samples seafloor macroorganisms by pumping and stabilizing the pressure inside the sampler using a pressure compensator. Firstly, the structure and working principle of the hydraulic suction macroorganism pressure-retaining sampler (HSMPS) were introduced. Then the flow field of the HSMPS sampling process was analyzed, and the velocity and pressure distribution of the flow field at different locations of the HSMPS were obtained. In response to the problem of the low viability of samples collected by deep-sea biological samplers, the changes in radial velocity and pressure at different positions of the sampler under different pumping flows were analyzed. Finally, the appropriate suction flow rate was selected based on the analysis results, and HSMPS suction tests and simulated sampling tests, under a 110 MPa high-pressure environment, were carried out using the developed HSMPS engineering prototype. The test results verify the feasibility of the HSMPS design, which will provide strong support for the deep abyssal seafloor sampling operation of the full-ocean-depth manned submersible. Full article
(This article belongs to the Special Issue Hydrodynamics of Offshore Structures)
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20 pages, 7138 KiB  
Article
Stability Analysis of a TLP with Inclined Tension Legs under Different Marine Survival Conditions
by Naying Wei, Zhen Zhang, Xu Xu and Wenjuan Yao
J. Mar. Sci. Eng. 2022, 10(8), 1058; https://doi.org/10.3390/jmse10081058 - 31 Jul 2022
Cited by 1 | Viewed by 2145
Abstract
To verify that inclined tension legs can improve the stability of the tension leg platform, this paper established the dynamic equation of a tension leg platform (TLP) under marine environmental loads by using the modified Morrison equation considering the influence of ocean currents [...] Read more.
To verify that inclined tension legs can improve the stability of the tension leg platform, this paper established the dynamic equation of a tension leg platform (TLP) under marine environmental loads by using the modified Morrison equation considering the influence of ocean currents on wave forces. Additionally, the velocity and acceleration of random wave water particles were simulated via the JONSWAP spectrum. In addition, a three-dimensional model of a tension leg platform with inclined tension legs was established by AQWA, and its dynamic responses under variable survival conditions were compared and analyzed. The results showed that the surge and heave were more sensitive to the sea current, while the pitch was more sensitive to the wind. There is a significant difference in tendon tensions between the atypical TLP with inclined tension legs established in this study and the typical International Ship and Offshore Structures Committee (ISSC) TLP. Full article
(This article belongs to the Special Issue Hydrodynamics of Offshore Structures)
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16 pages, 8059 KiB  
Article
Design and Reconfiguration of Multicomponent Hydrodynamic Manipulation Devices with Arbitrary Complex Structures
by Haixiang Pang, Yunxiang You, Tingqiu Li, Ke Chen and Li Sheng
J. Mar. Sci. Eng. 2022, 10(7), 861; https://doi.org/10.3390/jmse10070861 - 24 Jun 2022
Cited by 2 | Viewed by 1512
Abstract
Being a powerful strategy to preclude drag and achieve hydrodynamic invisibility, flow field manipulation is attracting widespread attention. In this investigation, we introduce a systematic set of arbitrary-space divide-and-conquer transformation strategies to design complex hydrodynamic cloaks. This theory removes the difficulties associated with [...] Read more.
Being a powerful strategy to preclude drag and achieve hydrodynamic invisibility, flow field manipulation is attracting widespread attention. In this investigation, we introduce a systematic set of arbitrary-space divide-and-conquer transformation strategies to design complex hydrodynamic cloaks. This theory removes the difficulties associated with the analytic description of complicated and irregular structures to construct hydrodynamic cloaks by adopting the divide-and-conquer algorithm and reconfiguring strategies. It also provides an approach for redistributing the flow field energy and guiding the fluid flow as desired. The proposed theory not only opens up new ideas for improving the speed and concealment of marine vehicles but also provides a new strategy for ensuring the safety of aquatic and underwater structure operations. Full article
(This article belongs to the Special Issue Hydrodynamics of Offshore Structures)
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20 pages, 1814 KiB  
Article
Near-Optimal Control for Offshore Structures with Nonlinear Energy Sink Mechanisms
by Wei Chen, Xingyu Du, Bao-Lin Zhang, Zhihui Cai and Zhongqiang Zheng
J. Mar. Sci. Eng. 2022, 10(6), 817; https://doi.org/10.3390/jmse10060817 - 14 Jun 2022
Cited by 3 | Viewed by 1782
Abstract
To improve the safety and reliability of offshore structures subject to wave loading, the active vibration control problem is always one of significant issues in the field of ocean engineering. This paper deals with the near–optimal control problem of offshore structures with a [...] Read more.
To improve the safety and reliability of offshore structures subject to wave loading, the active vibration control problem is always one of significant issues in the field of ocean engineering. This paper deals with the near–optimal control problem of offshore structures with a nonlinear energy sink (NES) mechanism. By taking the dominant vibration mode of the offshore structure with the NES into account, a nonlinear dynamic model of the steel–jacket structure subject to wave loading is presented first. Then, using the parameter perturbation approach to solve a nonlinear two–point boundary value problem, an NES–based optimal controller with the form of infinite series sum is presented to suppress the vibration of the offshore structure. Third, an iteration algorithm is provided to obtain the near–optimal controller. Simulation results demonstrate that the NES–based near–optimal controller can mitigate the oscillation amplitude of offshore structures significantly. Moreover, the NES–based optimal controller outperforms the one based on active tuned mass damper. Full article
(This article belongs to the Special Issue Hydrodynamics of Offshore Structures)
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17 pages, 2791 KiB  
Article
Evaluation of Dynamic Tensions of Single Point Mooring System under Random Waves with Artificial Neural Network
by Peng Li, Conglin Jin, Gang Ma, Jie Yang and Liping Sun
J. Mar. Sci. Eng. 2022, 10(5), 666; https://doi.org/10.3390/jmse10050666 - 13 May 2022
Cited by 6 | Viewed by 1934
Abstract
Real-time monitoring of the mooring safety of floating structures is of great significance to their production operations. A deep learning model is proposed here, based on the long short-term memory (LSTM) artificial neural network. Firstly, the numerical simulation is carried out with the [...] Read more.
Real-time monitoring of the mooring safety of floating structures is of great significance to their production operations. A deep learning model is proposed here, based on the long short-term memory (LSTM) artificial neural network. Firstly, the numerical simulation is carried out with the single-point mooring system of a Floating Production Storage and Offloading (FPSO) as the training data of LSTM. Then the proposed LSTM is performed. Finally, taking the motion of FPSO which is not encountered by LSTM neural network model as input, we predict the mooring line tension with this model. Here, one FPSO in the South China Sea is taken as a research case, hydrodynamic and mooring models are established, and the network structure and hyper-parameters of the LSTM model are determined. The prediction results of the LSTM under different combinations of wind, wave, and current are compared with the calculation results of AQWA software. The model constructed here can well predict the mooring line tension of different combinations of wind, wave and current. Full article
(This article belongs to the Special Issue Hydrodynamics of Offshore Structures)
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