On the Application of Advanced Wave Analysis in Shallow Water Model Testing (Wave Splitting)

Waals, Olaf

doi:10.1115/omae2009-79413

Cited by 10 publications

(14 citation statements)

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“…The sloping bottom is 300-meter long and its slope is 1/20. According to recent researches, simulating wave propagation over sloping bottom requires special treatments because nonlinear low frequency component could be generated by reflection and shoaling (Voogt, 2005;Waals, 2009). Fig.…”

Section: Wish-offshorementioning

confidence: 99%

Time-domain analysis of nonlinear motion responses and structural loads on ships and offshore structures: development of WISH programs

Kim

et al. 2011

International Journal of Naval Architecture and Ocean Engineeri

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The present paper introduced a computer program, called WISH, which is based on a time-domain Rankine panel method. The WISH has been developed for practical use to predict the linear and nonlinear ship motion and structural loads in waves. The WISH adopts three different levels of seakeeping analysis: linear, weakly-nonlinear and weak-scatterer approaches. Later, WISH-FLEX has been developed to consider hydroelasticity effects on hull-girder structure. This program can solve the springing and whipping problems by coupling between the hydrodynamic and structural problems. More recently this development has been continued to more diverse problems, including the motion responses of multiple adjacent bodies, the effects of seakeeping in ship maneuvering, and the floating-body motion in finite-depth domain with varying bathymetry. This paper introduces a brief theoretical and numerical background of the WISH package, and some validation results. Also several applications to real ships and offshore structures are shown.

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Section: Wish-offshorementioning

confidence: 99%

Time-domain analysis of nonlinear motion responses and structural loads on ships and offshore structures: development of WISH programs

Kim

et al. 2011

International Journal of Naval Architecture and Ocean Engineeri

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“…By exploiting their different wavelengths and directions, we can reliably separate the three wave components at using a wave-splitting procedure [35,36]. We can assume , = ( ) to have the form: The magnitude of the difference-frequency wave amplitude, |A d |, is significantly lower than those at the wave frequencies, but it varies strongly with x.…”

Section: Wave-only Simulationmentioning

confidence: 99%

Uncertainty Assessment of CFD Investigation of the Nonlinear Difference-Frequency Wave Loads on a Semisubmersible FOWT Platform

et al. 2020

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Current mid-fidelity modeling approaches for floating offshore wind turbines (FOWTs) have been found to underpredict the nonlinear, low-frequency wave excitation and the response of semisubmersible FOWTs. To examine the cause of this underprediction, the OC6 project is using computational fluid dynamics (CFD) tools to investigate the wave loads on the OC5-DeepCwind semisubmersible, with a focus on the nonlinear difference-frequency excitation. This paper focuses on assessing the uncertainty of the CFD predictions from simulations of the semisubmersible in a fixed condition under bichromatic wave loading and on establishing confidence in the results for use in improving mid-fidelity models. The uncertainty for the nonlinear wave excitation is found to be acceptable but larger than that for the wave-frequency excitation, with the spatial discretization error being the dominant contributor. Further, unwanted free waves at the difference frequency have been identified in the CFD solution. A wave-splitting and wave load-correction procedure are presented to remove the contamination from the free waves in the results. A preliminary comparison to second-order potential-flow theory shows that the CFD model predicted significantly higher difference-frequency wave excitations, especially in surge, suggesting that the CFD results can be used to better calibrate the mid-fidelity tools.

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“…The results of past experiments [9] have shown that even a bathymetry as simple as a constant sloping seabed can be difficult to model accurately using a diffraction code. Extensive additional research is carried out in the HA W AI Joint Industry Project, [10] and [11], in which knowledge on waves from the field of coastal engineering is combined with the knowledge of hydrodynamics of moored vessels. The aim of that project is to gain insight in the complex physics related to the hydrodynamics of vessels moored in coastal areas.…”

Section: Time-domain Simulation Modelmentioning

confidence: 99%

“…Furthermore the interaction of waves in the basin with the headland or with the shallow water area near the location of the plant may be sources of low-frequency wave energy near the vessel, without these leading to vessel motions. Research such as performed in the HAWAI Joint Industry Project [10] and [11] is required to identify the wave-and shiprelated hydrodynamic processes involved.…”

Section: Need For Further Randdmentioning

confidence: 99%

Motions and Mooring Loads of an LNG-Carrier Moored at a Jetty in a Complex Bathymetry

Weiler

Cozijn

Wijdeven

et al. 2009

Volume 1: Offshore Technology

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The Yemen LNG Company Ltd. is working on the design and construction of an LNG plant in the Republic of Yemen. The LNG plant, located at Balhaf on the Gulf of Aden, includes a jetty approximately 750 m from the shore to allow loading of LNG carriers. The bathymetry around the jetty is very complex and includes a large variation in water depth along the berth. Furthermore a cape near the jetty affects the incoming wave conditions. Deltares (formerly WL | Delft Hydraulics), together with MARIN, carried out a study of combined hydrodynamic scale model tests and computer simulations. The aim of the project was to determine the limiting environmental conditions for safe mooring of the LNG carriers at the jetty. The hydrodynamic scale model tests at Deltares focused on an accurate modeling of the wave conditions at the jetty and the motion response of the moored ship. To achieve this, the bathymetry around the jetty was modeled in detail, including the cape partially shielding the jetty from incoming waves from the open sea. Wind was applied to the moored ship as constant forces. The time-domain computer simulations were carried out by MARIN, using their TERMSIM simulation model. After calibration against scale model test results, the numerical model was used to quantify the effect of gusting wind for all environmental conditions and all ships as tested in the basin. The results of the scale model tests, corrected for the effect of gusting wind, indicated that the vessel can stay safely moored at the jetty in quite severe conditions. This leads to a high jetty availability, which is a favorable outcome of the project. After describing, in a general way, the methodology and results of the project, this paper focuses on the comparison of the results of the model tests with those of the computer simulations. This comparison showed that the low frequency effects, both excitation and response, in the complex bathymetry that was considered here, are very complex and beyond the present numerical modeling capabilities. Therefore, in the short term, physical model testing will remain necessary for an accurate prediction of the moored ship’s response in such situations. For the longer term the development of additional analysis and simulation methods is required.

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On the Application of Advanced Wave Analysis in Shallow Water Model Testing (Wave Splitting)

Cited by 10 publications

References 0 publications

Time-domain analysis of nonlinear motion responses and structural loads on ships and offshore structures: development of WISH programs

Time-domain analysis of nonlinear motion responses and structural loads on ships and offshore structures: development of WISH programs

Uncertainty Assessment of CFD Investigation of the Nonlinear Difference-Frequency Wave Loads on a Semisubmersible FOWT Platform

Motions and Mooring Loads of an LNG-Carrier Moored at a Jetty in a Complex Bathymetry

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