An operational investigation of wave slamming detection

The CFD software FLUENT was used as the foundation to develop the numerical wave flume, in which the governing equations are the Reynolds-averaged Navier-Stokes (RANS) equations and the standard k~ε turbulence model. The wave generating and absorbing were introduced into the RANS equations as the source terms using the relaxation approach. A new module of the wave generating and absorbing function, which is suitable for FLUENT based on the volume of fluid method (VOF), was established. Within the numerical wave flume, the reflected waves from the model within the computation domain can be absorbed effectively before second reflection appears due to the wave generating boundary. The computational results of the wave pressures on the bottom of the rectangular slab were validated for the different relative clearance by the experimental data. Good agreements were found.

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Bifurcation behaviour and wave slamming force on a compliant horizontal cylinder

Engineering Structures ◽

10.1016/0141-0296(95)00210-3 ◽

1996 ◽

Vol 18 (9) ◽

pp. 675-684

Author(s):

C.Y. Liaw ◽

K.Y. Lam ◽

E.S. Chan ◽

H.F. Cheong ◽

N.J. Shankar

Keyword(s):

Horizontal Cylinder ◽

Wave Slamming ◽

Bifurcation Behaviour

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Detailed Study on Breaking Wave Interactions With a Jacket Structure Based on Experimental Investigations

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4037829 ◽

2017 ◽

Vol 140 (2) ◽

Author(s):

Jithin Jose ◽

Olga Podrażka ◽

Ove Tobias Gudmestad ◽

Witold Cieślikiewicz

Keyword(s):

Wind Turbines ◽

Wave Breaking ◽

Offshore Structures ◽

Offshore Wind ◽

Wave Forces ◽

Breaking Wave ◽

Offshore Wind Turbines ◽

Wave Parameters ◽

Wave Slamming ◽

Breaking Wave Forces

Wave breaking is one of the major concerns for offshore structures installed in shallow waters. Impulsive breaking wave forces sometimes govern the design of such structures, particularly in areas with a sloping sea bottom. Most of the existing offshore wind turbines were installed in shallow water regions. Among fixed-type support structures for offshore wind turbines, jacket structures have become popular in recent times as the water depth for fixed offshore wind structures increases. However, there are many uncertainties in estimating breaking wave forces on a jacket structure, as only a limited number of past studies have estimated these forces. Present study is based on the WaveSlam experiment carried out in 2013, in which a jacket structure of 1:8 scale was tested for several breaking wave conditions. The total and local wave slamming forces are obtained from the experimental measured forces, using two different filtering methods. The total wave slamming forces are filtered from the measured forces using the empirical mode decomposition (EMD) method, and local slamming forces are obtained by the frequency response function (FRF) method. From these results, the peak slamming forces and slamming coefficients on the jacket members are estimated. The breaking wave forces are found to be dependent on various breaking wave parameters such as breaking wave height, wave period, wave front asymmetry, and wave-breaking positions. These wave parameters are estimated from the wave gauge measurements taken during the experiment. The dependency of the wave slamming forces on these estimated wave parameters is also investigated.

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Wave-Vessel Interactions in Beam Seas

Volume 4: Ocean Engineering; Ocean Renewable Energy; Ocean Space Utilization, Parts A and B ◽

10.1115/omae2009-79605 ◽

2009 ◽

Author(s):

Eirini Spentza ◽

Chris Swan

Keyword(s):

Wave Field ◽

Incident Wave ◽

Laboratory Data ◽

Wave Structure ◽

Wave Pattern ◽

Scaled Model ◽

Beam Seas ◽

Wave Basin ◽

Wave Slamming ◽

Speed Of Propagation

This paper concerns the nonlinear interaction of waves with a floating vessel. A detailed experimental study has been undertaken in a 3-D wave basin, using a scaled model tanker subject to a variety of incident wave conditions. The vessel, which is free to move in heave, pitch and roll, has a draft of 14m (at full-scale) and is subject to a range of incident wave periods propagating at right angles to the side shell of the vessel. Measurements undertaken with and without the vessel in place allow the diffracted-radiated wave field to be identified. The laboratory data indicate that the diffracted-radiated wave pattern varies significantly with the incident wave period. Detailed analysis of the experimental results has identified a hitherto unexpected second-order freely propagating wave harmonic generated due to the presence of the vessel. Given its frequency content and its relatively slow speed of propagation, this harmonic leads to a significant steepening of the wave field around the vessel and therefore has an important role to play in terms of the occurrence of wave slamming. Physical insights are provided concerning the latter and the practical implications of the overall wave-structure interactions are considered.

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An Assessment of Load and Response for Horizontal Slamming Loads From Model Scale Experiments

Volume 3: Structures, Safety, and Reliability ◽

10.1115/omae2018-78355 ◽

2018 ◽

Author(s):

Martin Storheim ◽

Gunnar Lian

Keyword(s):

Structural Response ◽

Breaking Waves ◽

Offshore Structures ◽

Load Level ◽

Material Behavior ◽

Wave Impact ◽

Large Variability ◽

Slamming Load ◽

Reasonable Approach ◽

Wave Slamming

Steep breaking waves can result in high impact loads on offshore structures, and several model test campaigns have been conducted to assess the effect of horizontal wave slamming. High loads have been measured, and they can be challenging to withstand without significant deformation. For wave slamming problems it is common to estimate the characteristic slamming load and assume that this will give an equivalent characteristic response. One challenge related to the slamming load is that it has a large variability in load level, the duration of the load and the shape of the overall load pulse. This variability can have a large impact on the estimated response to the characteristic load, causing a similar or larger variability in response. Due to the sensitivity to the structural response, it may be difficult to interpret large amounts of such data to arrive at a relevant design load without making overly conservative assumptions. This paper investigates the sensitivity of the structural response to assumptions made in the material modelling and how the short term variability is affected if we instead of load use response indicators such as plastic strain and max deformation to arrive at a characteristic load. For this purpose, a simplified dynamic response model is created, and the recorded wave impact events can then be evaluated based on the predicted structural response from the simplified model. It was found that the structural response is sensitive to the structural configuration. The assumed material behavior and hydro-elastoplastic effects were identified to greatly affect the structural response. A reasonable approach to arrive at the q-annual response seems to be to first estimate the q-annual extreme slamming load, and then run the structural analysis on several of the measured slamming time series with the estimated q-annual extreme pressure.

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The suction effect during freak wave slamming on a fixed platform deck: Smoothed particle hydrodynamics simulation and experimental study

Physics of Fluids ◽

10.1063/1.5124613 ◽

2019 ◽

Vol 31 (11) ◽

pp. 117108 ◽

Cited By ~ 10

Author(s):

Peng-Nan Sun ◽

Min Luo ◽

David Le Touzé ◽

A-Man Zhang

Keyword(s):

Experimental Study ◽

Smoothed Particle Hydrodynamics ◽

Freak Wave ◽

Particle Hydrodynamics ◽

Wave Slamming ◽

Smoothed Particle

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Prediction of Extreme Wave Slamming Loads on a Fixed Platform

Volume 2: CFD and FSI ◽

10.1115/omae2018-78179 ◽

2018 ◽

Author(s):

Grzegorz P. Filip ◽

Wenzhe Xu ◽

Kevin J. Maki

Keyword(s):

Wave Structure ◽

Nonlinear Process ◽

Extreme Value ◽

Wave Loads ◽

Oil Platforms ◽

Offshore Oil Platforms ◽

Highly Nonlinear ◽

Extreme Load ◽

Wave Slamming ◽

Extreme Responses

Design of offshore oil platforms requires accurate prediction of the maximum wave loads due to slamming on horizontal decks. The physical processes that influence the load are the propagation of irregular short-crested wind-driven storm seas, wave breaking, and wave-structure interaction. Furthermore, the ocean is a stochastic environment, so the load and its maximum can be considered as random variables. Ideally, the designer would like to know not only the most probable extreme load, but also the extreme load distribution. In this paper we will use a novel technique to prescribe wave environments that lead to extreme responses so that high-fidelity simulations of the highly-nonlinear process can be investigated in detail. Specifically, the dynamics of the relative motion of the sea surface and the platform will be assumed via the selection of a sea spectrum, and the extreme-value probability distribution function (PDF) will be calculated for a given exposure window. The novel aspect of the work is in the way that a set of deterministic sea environments will be generated that are amenable for simulation with a state-of-the-art computational-fluid dynamics (CFD) software. The resulting wave environments will be simulated to estimate the extreme-value PDF.

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