Dynamics of Offshore Structures

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

Deadline for manuscript submissions: closed (15 February 2020) | Viewed by 19204

Special Issue Editor


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Guest Editor
SINTEF Ocean AS, Department of Ships and Ocean Structures, SINTEF Ocean, Postboks 4762 Torgard, N-7465 Trondheim, Norway
Interests: hydrodynamics; stability; seakeeping; dynamics of offshore structures; offshore renewable energy; potential flow
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Special Issue Information

Dear Colleagues,

From oil platforms to offshore renewable energy equipment, to fish farms and large floating structures, the offshore sector is composed of a variety of industries and applications.

Offshore installations pose particular engineering challenges in terms of their efficiency, operability and survivability in a potentially harsh environment which is the sea. The effects of wind, waves and current on the dynamic behaviour of these structures needs, therefore, to be properly assessed. Furthermore, technologies aimed at controlling their behaviour through active or passive processes are crucial for their success.

This Special Issue aims at collecting contributions reflecting the latest developments in offshore structures' dynamics. Submissions may address the problems by first principles, theoretical and numerical modelling, model and prototype testing, applications, case studies, operational studies or other scientifically based approaches.

This Special Issue encompasses, but is not limited to, the study of fixed and floating offshore platforms, dynamic positioning, pipelines and risers, cables and mooring, offshore renewable energy and aquaculture structures. Studies addressing marine operations in the installation and maintenance of offshore structures and on the control and optimization of arrays are also within the scope.

Contributions presenting novel creative approaches, properly supported by consistent scientific reasoning, are particularly welcomed.

Dr. José Miguel Rodrigues
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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

  • offshore structures
  • offshore dynamics
  • offshore hydrodynamics
  • offshore renewable energy
  • offshore array
  • offshore marine operations
  • very large floating structures
  • oil and gas

Published Papers (5 papers)

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Research

18 pages, 1741 KiB  
Article
Improved VIV Response Prediction Using Adaptive Parameters and Data Clustering
by Jie Wu, Decao Yin, Halvor Lie, Signe Riemer-Sørensen, Svein Sævik and Michael Triantafyllou
J. Mar. Sci. Eng. 2020, 8(2), 127; https://doi.org/10.3390/jmse8020127 - 17 Feb 2020
Cited by 18 | Viewed by 2798
Abstract
Slender marine structures such as deep-water riser systems are continuously exposed to currents, leading to vortex-induced vibrations (VIV) of the structure. This may result in amplified drag loads and fast accumulation of fatigue damage. Consequently, accurate prediction of VIV responses is of great [...] Read more.
Slender marine structures such as deep-water riser systems are continuously exposed to currents, leading to vortex-induced vibrations (VIV) of the structure. This may result in amplified drag loads and fast accumulation of fatigue damage. Consequently, accurate prediction of VIV responses is of great importance for the safe design and operation of marine risers. Model tests with elastic pipes have shown that VIV responses are influenced by many structural and hydrodynamic parameters, which have not been fully modelled in present frequency domain VIV prediction tools. Traditionally, predictions have been computed using a single set of hydrodynamic parameters, often leading to inconsistent prediction accuracy when compared with observed field measurements and experimental data. Hence, it is necessary to implement a high safety factor of 10–20 in the riser design, which increases development costs and adds extra constraints in the field operation. One way to compensate for the simplifications in the mathematical prediction model is to apply adaptive parameters to describe different riser responses. The objective of this work is to demonstrate a new method to improve the prediction consistency and accuracy by applying adaptive hydrodynamic parameters. In the present work, a four-step approach has been proposed: First, the measured VIV response will be analysed to identify key parameters to represent the response characteristics. These parameters will be grouped by using data clustering algorithms. Secondly, optimal hydrodynamic parameters will be identified for each data group by optimisation against measured data. Thirdly, the VIV response using the obtained parameters will be calculated and the prediction accuracy evaluated. Last but not least, classification algorithms will be applied to determine the correct hydrodynamic parameters to be used for new cases. An iteration of the previous steps may be needed if the prediction accuracy of the new case is not satisfactory. This concept has been demonstrated with examples from experimental data. Full article
(This article belongs to the Special Issue Dynamics of Offshore Structures)
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24 pages, 4874 KiB  
Article
An Effective Multiscale Methodology for the Analysis of Marine Flexible Risers
by B. D. Edmans, D. C. Pham, Z.-Q. Zhang, T. F. Guo, N. Sridhar and G. Stewart
J. Mar. Sci. Eng. 2019, 7(10), 340; https://doi.org/10.3390/jmse7100340 - 28 Sep 2019
Cited by 7 | Viewed by 4578
Abstract
Life extension is an attractive option for subsea flexible risers nearing the end of their design lives. However, techniques for assessing accumulated fatigue damage in flexible risers are often associated with large uncertainties due to the simplified calculation approaches typically used. One approach [...] Read more.
Life extension is an attractive option for subsea flexible risers nearing the end of their design lives. However, techniques for assessing accumulated fatigue damage in flexible risers are often associated with large uncertainties due to the simplified calculation approaches typically used. One approach to reducing uncertainties is the inclusion of nonlinearities in riser structural response and consistent linking between global and local models. In this article, we present the elements of a numerical multiscale procedure capable of predicting the stresses that lead to fatigue damage in flexible pipes, namely: a nonlinear beam element, a nonlinear section response model and a detailed finite element model; the consistent integration of models developed for different length scales; and finally a validation of the flexible riser large-scale model. Full article
(This article belongs to the Special Issue Dynamics of Offshore Structures)
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11 pages, 1516 KiB  
Article
Frequency Domain Response of Jacket Platforms under Random Wave Loads
by Xiaoshuang Han, Weiliang Qiao and Bo Zhou
J. Mar. Sci. Eng. 2019, 7(10), 328; https://doi.org/10.3390/jmse7100328 - 21 Sep 2019
Cited by 11 | Viewed by 2299
Abstract
This article presents a procedure that simplifies an offshore jacket platform as a non-uniform cantilever beam subjected to an axial force. A Ritz method combined with a pseudo-excitation method is then used to analyze the responses of the jacket platform under random wave [...] Read more.
This article presents a procedure that simplifies an offshore jacket platform as a non-uniform cantilever beam subjected to an axial force. A Ritz method combined with a pseudo-excitation method is then used to analyze the responses of the jacket platform under random wave loads with the associated power spectral densities, variances and higher spectral moments. The theoretical basis and pertinent governing equations are derived. The proposed procedure not only eases the process of determining the pseudo wave loads, but also requires only the rudimentary structural details that are typically available at the preliminary design stage. Additionally, the merit of the proposed procedure is that the process does not require one to compute the normal modes, which saves time and is particularly convenient for the dynamic-response analysis of a complex structure (such as an offshore platform). An illustrative example based on a three-deck jacket platform is presented to demonstrate the procedure used to obtain the power spectral densities, variances and second spectral moments of jacket-top displacement and the bending moment of the jacket at the mud line. The results obtained are compared with those obtained using a Finite Element Mothed (FEM) model. Based on the findings of the study and good agreement shown in the comparison of results, it is concluded that the proposed method is effective, simple and convenient, and can be a useful tool for the preliminary design analysis of offshore platforms. Full article
(This article belongs to the Special Issue Dynamics of Offshore Structures)
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14 pages, 2240 KiB  
Article
Dynamic Analysis of an Array of Connected Floating Breakwaters
by Ivan Ćatipović, Maro Ćorak, Neven Alujević and Joško Parunov
J. Mar. Sci. Eng. 2019, 7(9), 298; https://doi.org/10.3390/jmse7090298 - 30 Aug 2019
Cited by 6 | Viewed by 2846
Abstract
In this paper, a model for dynamic analysis of array of floating breakwaters is developed and tested. Special attention is given to modeling connections between neighboring elements of the array. A linear three-dimensional floating multi-body formulation is used as a foundation for the [...] Read more.
In this paper, a model for dynamic analysis of array of floating breakwaters is developed and tested. Special attention is given to modeling connections between neighboring elements of the array. A linear three-dimensional floating multi-body formulation is used as a foundation for the presented model. An additional stiffness matrix is derived which introduces the influence of the connections onto motion of the array. The stiffness matrix is used to couple motions in vertical and horizontal planes i.e., the connections are modeled in three-dimensions. The equation of motion is solved in the frequency domain. The newly developed model is tested on an array of three connected breakwaters. The motion and the performance of the breakwater array are investigated under different significant heights and directions of the incoming waves. Full article
(This article belongs to the Special Issue Dynamics of Offshore Structures)
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19 pages, 5025 KiB  
Article
HAMS: A Frequency-Domain Preprocessor for Wave-Structure Interactions—Theory, Development, and Application
by Yingyi Liu
J. Mar. Sci. Eng. 2019, 7(3), 81; https://doi.org/10.3390/jmse7030081 - 26 Mar 2019
Cited by 47 | Viewed by 5426
Abstract
This paper presents the theoretical background, the numerical implementation, and the applications of a new software that has been developed in recent years for the analysis of wave-structure interactions. The software is developed in the frequency domain, as a preprocessor of computing the [...] Read more.
This paper presents the theoretical background, the numerical implementation, and the applications of a new software that has been developed in recent years for the analysis of wave-structure interactions. The software is developed in the frequency domain, as a preprocessor of computing the wave excitation force, the added mass, and the wave radiation damping, for the input to a time-domain solver via the Fourier cosine and sine transforms. In addition, it can also predict the motion responses of a marine structure with sufficient accuracy, with or without the presence of a mooring system. Unlike other frequency-domain software, such as WAMIT® and Hydrostar®, the present software currently employs the least squares method in association with a partially extended boundary integral equation method to remove the so-called “irregular frequencies”. Calculation of the free-surface Green’s function employs a combination of fast-convergent series expansions in different parametric sub-regions. The solution of the resultant linear algebraic system employs the lower-upper (LU) decomposition method. Symmetry properties can be exploited, and the open multi-processing (OpenMP) parallelization technique can be applied to reduce the computation burden. The accuracy and the efficiency of the developed software are finally confirmed by numerical validations on three benchmark cases of a floating ellipsoid, a truncated circular cylinder and the OC4 DeepCwind semisubmersible floating wind turbine. A free executable version of the software is available to the research communities with a hope of facilitating the advancements in the researches that are relevant to ocean engineering and marine renewable energies. Full article
(This article belongs to the Special Issue Dynamics of Offshore Structures)
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