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Journal ArticleDOI

Numerical studies on CALM buoy motion responses and the effect of buoy geometry cum skirt dimensions with its hydrodynamic waves-current interactions

01 Jan 2022-Ocean Engineering-Vol. 244, pp 110378-110378
TL;DR: In this paper , numerical investigations on a free-floating Catenary Anchor Leg Moorings (CALM) buoy were carried out and an Orcaflex-coupled model of the CALM buoy system with submarine hoses in Lazy-S configuration was presented.
About: This article is published in Ocean Engineering.The article was published on 2022-01-01 and is currently open access. It has received 26 citations till now. The article focuses on the topics: Buoy & Mooring.

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Citations
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Journal ArticleDOI
TL;DR: In this article , the fluid-structure interaction (FSI) from wave diffraction forces on CALM buoys and cylindrical structures, based on the hydrodynamics with connections, was investigated.
Abstract: ABSTRACT This research fills the gap in understanding fluid–structure interaction (FSI) from wave diffraction forces on CALM buoys and cylindrical structures, based on the hydrodynamics with connections. Recently, there is an increased application of (un)loading marine hoses for Catenary Anchor Leg Moorings (CALM) buoy systems in the offshore industry due to the need for more flexible marine structures that are cost-saving, easier to install, and service. However, different operational issues challenge these hoses, like during hose disconnection. Also, the fluid behaviour was investigated based on the analytical and numerical models. The numerical modelling involves the boundary element method (BEM) and Orcaflex line theory. Hydrodynamic analysis is conducted on the disconnection-induced load response of marine bonded hoses during normal operation and accidental operation under irregular waves. A comparative study on hose performance during normal operation and accidental operation is also presented. Results of statistical analysis on CALM buoy system shows good motion characteristics.

20 citations

Journal ArticleDOI
TL;DR: In this paper , the authors presented the composite production risers (CPR) behavior with three different configurations: 17 layers, 18 layers, 19 layers, 20 layers, and 21 layers.

20 citations

Journal ArticleDOI
TL;DR: In this paper, experimental and numerical investigations are carried out on the dynamic behavior of the submarine hoses attached to a catenary anchor leg moorings (CALM) buoys in Lazy-S configuration.
Abstract: Recent design challenges in ocean observations, energy storage, offloading/discharging, and loading operations in both the offshore-renewable industry have led to advances in the application of catenary anchor leg moorings (CALM) buoys. Due to different seabed profiles, soil stiffness and environmental conditions, there is the need for numerical assessment to investigate the behaviour of the submarine hoses, based on the structural and hydrodynamic behaviour. In this study, experimental and numerical investigations are carried out on the dynamic behaviour of the submarine hoses attached to a CALM buoy in Lazy-S configuration. Six mooring lines are attached to the CALM buoy with a water depth of 100 m in the numerical model. A hydrodynamic model utilising ANSYS AQWA was developed then coupled unto the dynamic model in Orcina’s Orcaflex. The studies were carried out to study the effect of flow angles, wave height, soil stiffness and hydrodynamic loads on the structural behaviour of the submarine hoses. Waves at different angles to the submarine hose affected the effective tension more where the hose bends due to the floats attached. Parametric studies were carried out on both linear and nonlinear seabed models, and recommendations were made from the investigations on the submarine hose models.

19 citations

Journal ArticleDOI
TL;DR: In this article , a review on the design, hydrodynamics and mechanics of composite risers is presented, which covers both the structure of the composite production riser (CPR) and its end-fittings for offshore marine applications.
Abstract: In recent times, the utilisation of marine composites in tubular structures has grown in popularity. These applications include composite risers and related SURF (subsea umbilicals, risers and flowlines) units. The composite industry has evolved in the development of advanced composites, such as thermoplastic composite pipes (TCP) and hybrid composite structures. However, there are gaps in the understanding of its performance in composite risers, hence the need for this review on the design, hydrodynamics and mechanics of composite risers. The review covers both the structure of the composite production riser (CPR) and its end-fittings for offshore marine applications. It also reviews the mechanical behaviour of composite risers, their microstructure and strength/stress profiles. In principle, designers now have a greater grasp of composite materials. It was concluded that composites differ from standard materials such as steel. Basically, composites have weight savings and a comparative stiffness-to-strength ratio, which are advantageous in marine composites. Also, the offshore sector has grown in response to newer innovations in composite structures such as composite risers, thereby providing new cost-effective techniques. This comprehensive review shows the necessity of optimising existing designs of composite risers. Conclusions drawn portray issues facing composite riser research. Recommendations were made to encourage composite riser developments, including elaboration of necessary standards and specifications.

18 citations

Journal ArticleDOI
TL;DR: In this paper , a detailed presentation on motion characterisation of the Catenary Anchor Leg Moorings (CALM) buoy hose system is presented, which is a structure with six degrees of freedom (6DoF) and a well-detailed experimental presentation on the CALM buoy hose model conducted in Lancaster University Wave Tank is presented using three novel techniques.
Abstract: The application of marine bonded hoses has increased in recent times, due to the need for more flexible conduits and flexible applications in the offshore industry. These marine structures include Catenary Anchor Leg Moorings (CALM) buoys and ocean monitoring buoys. Their attachments include floating hoses, submarine hoses and submarine cables. However, the structural performance challenges of a CALM buoy system from its hydrodynamics water waves and other global loadings, have led to the need for this investigation. In this study, a detailed presentation on the motion characterisation of the CALM buoy hose system is presented. The CALM buoy is a structure with six degrees of freedom (6DoF). A well-detailed experimental presentation on the CALM buoy hose model conducted in Lancaster University Wave Tank is presented using three novel techniques, which are: a digital image captured using Imetrum systems, using an Akaso 4K underwater camera, using wave gauges arranged in a unique pattern and using underwater Bluetooth sensors. The buoy model was also found to respond uniquely for each motion investigated under water waves. The results showed that the higher the profile, the higher the response of the buoy. Thus, this study confirms the existence of flow patterns of the CALM buoy while floating on the water body.

17 citations

References
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Journal ArticleDOI
TL;DR: In this paper, the linearized frequency-domain analysis of wave radiation and diffraction by a three-dimensional body in a fixed mean position is extended to a variety of deformable body motions.

318 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a review of the recent advances in the assessment of loads for ships and offshore structures with the aim to draw the overall technological landscape available for further understanding, validation and implementation by the academic and industrial communities.

226 citations

Journal ArticleDOI
TL;DR: In this article, the authors discuss the potential-flow forces of the second order in the amplitude of ambient velocity fluctuations and the major role played by these forces in wave loading on offshore structures.
Abstract: This article is aimed at relating a certain substantial body of established material concerning wave loading on offshore structures to fundamental principles of mechanics of solids and of fluids and to important results by G. I. Taylor (1928a, b). The object is to make some key parts within a rather specialised field accessible to the general fluid-mechanics reader.The article is concerned primarily to develop the ideas which validate a separation of hydrodynamic loadings into vortex-flow forces and potential-flow forces; and to clarify, as Taylor (1928b) first did, the major role played by components of the potential-flow forces which are of the second order in the amplitude of ambient velocity fluctuations. Recent methods for calculating these forces have proved increasingly important for modes of motion of structures (such as tension-leg platforms) of very low natural frequency.

184 citations