Wave interaction with tension leg platforms
TL;DR: In this article, a series of small scale wave tank tests on four column TLP models examining wave run-up on the vertical legs and the amplification of the waves beneath the deck are reported.
About: This article is published in Ocean Engineering.The article was published on 1992-01-01. It has received 50 citations till now. The article focuses on the topics: Wave tank & Tension-leg platform.
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TL;DR: In this article, a Takagi-Sugeno (T-S) fuzzy model approach combined with a parallel distributed compensation (PDC) scheme is proposed for time-delay control of the response of a tension leg platform (TLP) system subjected to an external wave force.
Abstract: In this paper, a Takagi-Sugeno (T-S) fuzzy model approach combined with a parallel distributed compensation (PDC) scheme is proposed for time-delay control of the response of a tension leg platform (TLP) system subjected to an external wave force. A global PDC-based fuzzy logic controller is constructed by blending all local state feedback controllers. A fuzzy-model-based control is thereby developed which can attenuate the influence of the external wave force. The controller is evaluated in terms of stability analysis, and the linear matrix inequality (LMI) conditions guaranteeing the stability of the TLP system derived via Lyapunov theory. A simulation example is given to show the feasibility of the proposed fuzzy control approach. The example shows the concept of half-circle fuzzy number can be used in fuzzy control and the proposed control method can be employed in practical engineering problems of oceanic structure.
138 citations
Cites background from "Wave interaction with tension leg p..."
...Researchers have been investigating the wave-structure interaction problem for decades (Harms, 1979 Niedzwecki and Huston, 1992 Skourup et al., 1992 Shumina et al., 1996 Chen and Hsu, 2005 Chen et al., 2006a,b, 2007)....
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TL;DR: In this study, the Takagi-Sugeno (T-S) fuzzy model is employed to approximate the oceanic structure and a parallel-distributed-compensation (PDC) scheme is utilized in a control procedure designed to reduce the structural response.
89 citations
TL;DR: In this article, a physical model study of the run-up heights and runup distribution on two shapes of foundations for offshore wind turbines, including both regular and irregular waves, is presented.
78 citations
Cites background from "Wave interaction with tension leg p..."
...In another paper, Niedzwecki and Huston (1992) allow a second coefficient to vary the linear fit, and arrive at...
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...Linear theories include the velocity stagnation head theory as well as the suggestions from Niedzwecki and Duggal (1992) and Niedzwecki and Huston (1992)....
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...In another paper, Niedzwecki and Huston (1992) allow a second coefficient to vary the linear fit, and arrive at Ru ¼ 0:56H þ 6:52 u 2 2g ð5Þ for a single cylinder....
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...The suggestions made by Niedzwecki and Duggal (1992) and by Niedzwecki and Huston (1992) both overestimate the run-up for smaller wave heights, but for larger wave heights a substantial underprediction is observed....
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TL;DR: In this article, a literature review on offshore compliant structures is presented, focusing on the static and dynamic response of the structure due to various environmental conditions, such as wind, waves and current.
Abstract: Offshore compliant structures such as guyed platforms, tension leg platforms and articulated towers are economically attractive for deep water conditions because of their reduced structural weight compared to conventional platforms. The foundations of these kinds of structures do not resist lateral environmental loads forces; instead, restoring moments are provided by a large buoyancy force, a set of guylines or a combination of both. These structures have a fundamental frequency well below the ocean wave’s lower frequency-bound. As a result of the relatively large displacements, geometric nonlinearity is an important consideration in the analysis of such a structure. This paper presents a literature review on offshore compliant structures. The review focuses on the static and dynamic response of the structure due to various environmental conditions, such as wind, waves and current. Emphasis is placed on modeling techniques and methods of solution. Many modeling and analysis techniques are common to the aerospace and ocean engineering communities due to the similarities in structural and environmental complexities. For example, aerodynamic loads on offshore platforms are a significant part of any analysis. Also, fluid loading models bear great similarities to mechanistic wind loading models. It is in this vein that a review paper with the focus on offshore structures is included in a journal of aerospace engineering.
53 citations
TL;DR: In this article, the authors presented the benchmark simulations of wave run-up on a fixed single truncated circular cylinder and four circular cylinders, where the Navier-Stokes equations are employed as the governing equations, and the volume of fluid (VOF) method is applied for capturing the free surface.
34 citations
References
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Book•
01 Jan 1983
TL;DR: In this article, the basic physical laws used in oceanography and classifications of forces and motions in the sea are discussed, and the role of non-linear terms and the magnitudes of terms in the equations of motion are discussed.
Abstract: CONTENTS INCLUDE: Properties of seawater relevant to physical oceanography The basic physical laws used in oceanography and classifications of forces and motions in the sea The equation of continuity of volume The equation of motion in oceanography The role of the non-linear terms and the magnitudes of terms in the equations of motion Currents without friction - geostrophic flow Currents with friction - wind-driven circulation Numerical models Waves Tides.
745 citations
TL;DR: In this article, the second-order double-frequency diffraction potential of a vertically axisymmetric body is obtained explicitly by a sequence of one-dimensional integral equations along the generator of the body involving free-surface ring sources of general order.
Abstract: The authors studied the diffraction, to second order, of plane monochromatic incident gravity waves by a vertically axisymmetric body. The second-order double-frequency diffraction potential is obtained explicitly. A sequence of one-dimensional integral equations along the generator of the body involving free-surface ring sources of general order are formulated and solved for the circumferential components of the second-order potential. The solution is expedited by analytic integrations in the entire local-wave-free outer field of a requisite free-surface integral. The method is validated by extensive convergence tests and comparisons to semi-analytic results for the second-order forces and moments on a uniform vertical circular cylinder. Complete second-order forces, moments, surface pressures and run-up on the vertical cylinder as well as a truncated vertical cone are presented. A summary is given of the most important findings.
199 citations
TL;DR: In this article, simple rules are developed to estimate the maximum uplift pressures induced on the underside of a flat plate by various types of incident waves, including standing waves, regular progressive waves, and dispersive waves.
Abstract: Simple rules are developed to estimate the maximum uplift pressures induced on the underside of a flat plate by various types of incident waves. Theoretical prediction techniques are provided for both the slow-rise pressure component and the fast-rise pressure component (impact) for different incident waves: standing waves, regular progressive waves, and dispersive waves, all in constant water depth. Laboratory experiments were conducted in a dispersive wave basin partially to check the validity of prediction techniques and partially to provide additional information so that the prediction techniques can be extended empirically to cover the more complicated but more practical situation of a plate in shoaling water. The fast-rise pressure should be of engineering concern not only because the magnitude of its peak is enormous but also because the magnitude of the corresponding impulse is significant. The slow-rise pressure component was found to range from one to two times the hydrostatic pressure.
52 citations
TL;DR: In this paper, the peak water line around a vertical circular pile in periodic wave action is measured, showing a nonlinear dependence on incident wave height when the pile radius is very small compared to the wavelength.
Abstract: The measured pattern of peak water line around a vertical circular pile in periodic wave action can disagree with wave-scattering theory, showing a nonlinear dependence on incident wave height when the pile radius is very small compared to the wavelength. The peak water line was measured around piles of several diameters in relatively shallow water with various incident laboratory waves. Features of the patterns indicate that a disturbance like a ship's bow wave forms during peak crest flow when a certain Froude number, incident crest velocity head divided by pile radius, becomes large, on the order of 0.1 - 1.0. The laboratory tests shoudl reproduce basic flow effects in situations of coastal and ocean engineering interest, because field and lab situations have the same Froude number, implying geometric flow similarity.
45 citations