scholarly journals Experimental Data of a Hexagonal Floating Structure under Waves

Data ◽  
2021 ◽  
Vol 6 (10) ◽  
pp. 105
Author(s):  
Roman Gabl ◽  
Robert Klar ◽  
Thomas Davey ◽  
David M. Ingram
Keyword(s):  
Irregular Waves ◽  
Experimental Investigations ◽  
Mooring System ◽  
Floating Structure ◽  
Floating Structures ◽  
Validation Experiment ◽  
Wide Range ◽  
Wave Heights ◽  
The Individual ◽  
Six Degree Of Freedom

Floating structures have a wide range of application and shapes. This experimental investigations observes a hexagonal floating structure under wave conditions for three different draft configurations. Regular waves as well as a range of white noise tests were conducted to quantify the response amplitude operator (RAO). Further irregular waves focused on the survivability of the floating structure. The presented dataset includes wave gauge data as well as a six degree of freedom motion measurement to quantify the response only restricted by a soft mooring system. Additional analysis include the measurement of the mass properties of the individual configuration, natural frequency of the mooring system as well as the comparison between requested and measured wave heights. This allows us to use the provided dataset as a validation experiment.

A Numerically Efficient Method for Analysis of Very Large Articulated Floating Structures

1998 ◽  
Vol 42 (03) ◽  
pp. 174-186
Author(s):  
C. J. Garrison
Keyword(s):  
Hydrodynamic Interaction ◽  
Near Field ◽  
Three Dimensional ◽  
Computational Effort ◽  
Floating Structure ◽  
Complete Structure ◽  
Field Interaction ◽  
Floating Structures ◽  
Computing Effort ◽  
The Individual

A method is presented for evaluation of the motion of long structures composed of interconnected barges, or modules, of arbitrary shape. Such structures are being proposed in the construction of offshore airports or other large offshore floating structures. It is known that the evaluation of the motion of jointed or otherwise interconnected modules which make up a long floating structure may be evaluated by three dimensional radiation/diffraction analysis. However, the computing effort increases rapidly as the complexity of the geometric shape of the individual modules and the total number of modules increases. This paper describes an approximate method which drastically reduces the computational effort without major effects on accuracy. The method relies on accounting for hydrodynamic interaction effects between only adjacent modules within the structure rather than between all of the modules since the near-field interaction is by far the more important. This approximation reduces the computational effort to that of solving the two-module problem regardless of the total number of modules in the complete structure.

Yaw Drift Moment of a Floating Structure in Waves

2005 ◽  
Author(s):  
Dimitris Spanos ◽  
Apostolos Papanikolaou
Keyword(s):  
Hydrodynamic Forces ◽  
Computational Method ◽  
Irregular Waves ◽  
Linear Potential ◽  
Floating Bodies ◽  
Floating Structure ◽  
Natural Wave ◽  
Positioning Systems ◽  
Floating Structures ◽  
Wave Induced

The wave induced yaw drift moment on floating structures is of particular interest when the lateral yaw motion of the structure should be controlled by moorings and/or active dynamic positioning systems. In the present paper, the estimation of the yaw drift moment in the modeled natural wave environment is conducted by application of a nonlinear time domain numerical method accounting for the motion of arbitrarily shaped floating bodies in waves. The computational method is based on linear potential theory and includes the non-linear hydrostatic terms in an exact way, whereas the higher-order wave-induced effects are partly approximated. Despite the approximate modeling of the second order hydrodynamic forces, the method proved to satisfactorily approach the dominant part of the exerted hydrodynamic forces enabling the calculation of drift forces and of other drift effects in irregular waves. Hence, the subject yaw drift moment in the modeled natural wave environment is derived, resulting to a basic reference for the design of similar type floating structures.

Hydrodynamic Analysis of Multi-Body Floating Piers

2008 ◽  
Author(s):  
Zahra Tajali ◽  
Mehdi Shafieefar ◽  
Mahmood Akhyani
Keyword(s):  
Transfer Functions ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Dynamic Responses ◽  
Floating Structure ◽  
Hydrodynamic Analysis ◽  
Wide Range ◽  
The Individual ◽  
Multi Body ◽  
Wave Induced

Hydrodynamic analysis of a floating multi-body pier interacting with incident waves is carried out in the present research and results of wave-induced motions and structural responses are described. The objective is to develop a procedure which can be used to analyze the motions of such a floating structure consisting of a number of rigid pontoons linked together. Also, optimization of pontoons geometry for a desired length of the pier is examined. In this regard, different alternative arrangements of pontoons with different numbers and dimensions are studied and dynamic responses of these alternatives are investigated. Analysis of the multi-body floating structure is carried out in the frequency domain. The wave-induced forces and the responses are computed by three-dimensional diffraction method. To examine the effect of using different pontoons on pier hydrodynamic response, motion-amplitude transfer functions (RAO) and connector forces for a wide range of wave frequency and heading angle are computed. Results include the absolute and relative responses of the individual pontoons and prediction of pier motions for a wide variety of pontoon geometries in different wave frequencies and heading angles. Also results include effects of pontoons dimension on the response of structure and present heave, roll and pitch motions for floating pier structural system.

Numerical Simulation of a Spar Interacting With a Polyester Mooring System

2004 ◽  
Author(s):  
Minsuk Kim ◽  
Yu Ding ◽  
Jun Zhang
Keyword(s):  
Energy Dissipation ◽  
Cyclic Loads ◽  
Mooring System ◽  
Floating Structure ◽  
Mooring Lines ◽  
Floating Structures ◽  
System A ◽  
Large Elongation ◽  
The Mean ◽  
Offset Curve

A numerical scheme, known as CABLE3D, originally developed for the simulation of dynamics of steel mooring lines is extended to allow for special properties pertaining to polyester ropes, such as relatively large elongation under tension, dependence of the modulus on loads, and energy dissipation under cyclic loads. The modified CABLE3D is then integrated into a numerical package, known as COUPLE6D, for computing the interaction between a floating structure and its polyester mooring system. A classical SPAR is chosen in this study as a representative of deepwater floating structures. By considering large elongation in polyester ropes, the static offset curve of a polyester mooring system is softer than that calculated under the assumption of small elongation. The effects of the mean loads on the modulus of polyester ropes are much greater than those of the dynamic loads. The energy dissipation in polyester ropes under cyclic loading does not play a significant role in the responses of the SPAR and tensions in a polyester mooring system. The above observations though made based on a classical SPAR may still have important implications to other floating structures moored by a polyester mooring system.

scholarly journals ON JOINT DISTRIBUTION OF WAVE HEIGHTS AND DIRECTIONS

1988 ◽  
Vol 1 (21) ◽  
pp. 37 ◽  
Author(s):  
Masahiko Isobe
Keyword(s):  
Wave Height ◽  
Joint Distribution ◽  
Joint Probability ◽  
Irregular Waves ◽  
Wave Analysis ◽  
Wave Direction ◽  
Individual Wave ◽  
Wave Heights ◽  
The Individual ◽  
Joint Probability Density

In the individual wave analysis of short-crested irregular waves, the wave direction of an individual wave is an important quantity as well as the wave height and period. In this paper, the joint probability density of the wave height and direction is derived theoretically on the assumption of a narrow-banded frequency spectrum. A field experiment was carried out to examine the validity of the theory. The measured joint distribution agreed well with that predicted by the theory.

Hydrodynamic Interaction of Floating Structure in Regular Waves

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Hassan Abyn ◽  
Adi Maimun ◽  
Jaswar Jaswar ◽  
M. Rafiqul Islam ◽  
Allan Magee ◽  
...  
Keyword(s):  
Hydrodynamic Interaction ◽  
Oil And Gas ◽  
Irregular Waves ◽  
Source Distribution ◽  
Floating Bodies ◽  
Floating Structure ◽  
Distribution Method ◽  
Floating Structures ◽  
Motion Responses ◽  
Hydrodynamics Coefficients

Floating structures play an important role for exploring the oil and gas from the sea. In loading and offloading, motion responses of offshore floating structures are affected through hydrodynamic interaction. Large motions between floating bodies would cause the damage of moorings, offloading system and may colloid to each other. This research studies on hydrodynamic interaction between Tension Leg Platform (TLP) and Semi-Submersible (Tender Assisted Drilling (TAD)) in regular and irregular waves with scenario as follows: fixed TLP and 6-DOF floating semi-submersible and 6-DOF both TLP and semi-submersible. Under these conditions, hydrodynamics coefficients, mooring and connectors forces, motions and relative motions of TLP and Semi-Submersible will be simulated numerically by using 3D source distribution method. As the scope is big, this paper only presents model experiment of floating TLP and semi-submersible in the regular wave. The experiment is carried out in the UTM Towing Tank.

Numerical Investigation on Interaction Between a Semi-Submersible Platform and its Mooring System

2015 ◽  
Author(s):  
Yuanchuan Liu ◽  
Yao Peng ◽  
Decheng Wan
Keyword(s):  
Mooring Line ◽  
Mooring System ◽  
Floating Structure ◽  
Mooring Lines ◽  
Flow Solver ◽  
Floating Structures ◽  
Marine Renewable Energy ◽  
Motion Responses ◽  
Increasing Demand ◽  
Energy Engineering

With the increasing demand of floating structures in offshore, coastal and marine renewable energy engineering, the interaction between the mooring system and floating structure becomes more and more important. In this paper, motion responses of a semi-submersible platform with mooring system under regular wave conditions are investigated numerically by a viscous flow solver naoe-FOAM-SJTU based on the open source toolbox OpenFOAM. Influence of the mooring system on the platform motion responses is evaluated in two different ways. Investigations are covered for analysis methods adopted for solving mooring lines and the length of each part of a multi-component mooring line. Several important conclusions are drawn.

Experimental and Numerical Study of the Motions of a Turret Moored FPSO in Waves

2004 ◽  
Vol 127 (3) ◽  
pp. 197-204 ◽  
Author(s):  
C. Guedes Soares ◽  
N. Fonseca ◽  
R. Pascoal
Keyword(s):  
Degrees Of Freedom ◽  
Numerical Study ◽  
Numerical Data ◽  
Irregular Waves ◽  
Experimental Program ◽  
Six Degrees Of Freedom ◽  
Strip Theory ◽  
Wide Range ◽  
Wave Heights ◽  
Mooring Forces

This paper presents the results of an experimental program carried out with a model of a FPSO (Floating Production, Storage and Offloading) unit moored and subjected to incoming waves. In regular waves, a wide range of wavelengths were tested and the effect of the wave amplitude was also investigated. In irregular waves the model was subjected to different sea states, including very severe significant wave heights. The measured responses include the six degrees of freedom absolute motions, relative motions, and the mooring forces. The experimental data of surge, heave, and pitch is compared with calculated results from a Green’s function panel method and a strip theory program. In general, the agreement between experimental and numerical data is very good.

Oscillating Wave Surge Converter-Type Attachment for Extracting Wave Energy While Reducing Hydroelastic Responses of Very Large Floating Structures

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
H. P. Nguyen ◽  
C. M. Wang
Keyword(s):  
Wave Energy ◽  
Wave Force ◽  
Mooring System ◽  
Energy Converter ◽  
Floating Structure ◽  
Incident Wavelength ◽  
Floating Structures ◽  
Horizontal Wave ◽  
Horizontal Wave Force ◽  
Better Than

Abstract This paper presents an oscillating wave surge converter (OWSC)-type attachment, comprising a submerged vertical flap connected to the fore edge of a very large floating structure (VLFS) with hinges and linear power take-off (PTO) systems, for extracting wave energy while reducing hydroelastic responses of VLFS. In terms of reductions in hydroelastic responses of VLFS, the OWSC-type attachment is better than the recently proposed raft wave energy converter (WEC)-type attachment for relatively short waves (T < 7 s) and better than the conventional anti-motion device comprising a submerged vertical flap rigidly connected to the fore edge of VLFS for all wave periods. Importantly, the horizontal wave force acting on the submerged flap for the OWSC-type attachment is smaller than that for the conventional anti-motion device, leading to a more economical mooring system. In terms of wave energy extraction, the OWSC-type attachment is better than the raft WEC-type attachment for intermediate and long waves (T ≥ 7 s). In addition, for maximizing power production, the required flap length for the OWSC-type attachment is much smaller than the required pontoon length for the raft WEC-type attachment (about λ/10 as compared to about λ/3, where λ is the incident wavelength).

Optimization of Mooring System for Multi-Arrayed Tidal Turbines in a Strong Current Area

2014 ◽  
Author(s):  
Yu-ho Rho ◽  
Chul-hee Jo ◽  
Do-youb Kim
Keyword(s):  
Power Systems ◽  
Tidal Current ◽  
Mooring Line ◽  
Limited Area ◽  
Mooring System ◽  
Ocean Energy ◽  
Floating Structure ◽  
Energy Potential ◽  
Mooring Lines ◽  
Floating Structures

Recently, focus has been placed on ocean energy resources as environmental concerns regarding the exploitation of hydrocarbons are increasing. The enormous energy potential in tidal current power fields has been exploited by installing floating tidal current power turbines. Due to other floating structures operating within a limited area, stationkeeping is needed in order to keep the motions of the floating structures within permissible limits. In this study, methods for selecting and optimizing the mooring system for floating tidal current power systems in shallow water are investigated. The mooring system provides restoring forces and moments on a floating structure, pulling the structure back toward its equilibrium position. Typically, the mooring lines are segmented in order to optimize the force and displacement characteristics known as the mooring line characteristics. The mooring system concepts investigated in this study include the distributed mass, clump weight, and buoyancy element mooring systems.

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