Large-Scale Model Tests With Wave Loading on Offshore Platform Deck Elements

2002 ◽  
Author(s):  
Martin J. Sterndorff
Keyword(s):  
Large Scale ◽  
Model Tests ◽  
Offshore Platform ◽  
Irregular Waves ◽  
Scale Model ◽  
Wave Forces ◽  
Wave Loading ◽  
Large Wave ◽  
Wave Channel ◽  
The Individual

The present paper concerns a detailed large-scale experimental study of wave loading on offshore platform decks. A series of model tests with wave loading on different types of deck elements have been performed in the large wave channel (GWK) at Forschungszentrum Kiiste in Hannover, Germany. The following types of deck elements have been considered: tubular elements, plate profiles, and HEB beam profiles. The tests have been performed with individual elements and arrays of elements. Tests have also been performed with an array of beam elements covered with deck plating. A large range of different wave types, air gaps, and inundation’s have been tested. Regular waves with wave height ranging from 1.4 m to 1.8 m, irregular waves and wave packages with crest heights ranging from 0.9 m to 1.6 m have been tested. During the tests the following parameters were measured: wave elevations, deck element inundation’s, wave kinematics profile, and wave forces on the individual deck elements. The model test results will be analysed to provide hydrodynamic load coefficients to a wave-in-deck load programme based on the concept of change of fluid momentum. The results will also be used to verify a CFD code based on the Volume of Fluid method.

Small and Large Scale Experimental Investigations of Wave Loads on a Slender Pile Within Closely Spaced Neighbouring Piles

2014 ◽  
Author(s):  
Lisham Bonakdar ◽  
Hocine Oumeraci
Keyword(s):  
Laboratory Tests ◽  
Large Scale ◽  
Model Tests ◽  
Scale Model ◽  
Research Centre ◽  
Experimental Investigations ◽  
Small Scale ◽  
Wave Loads ◽  
Large Wave ◽  
Wave Flume

Wave loads on a slender pile within a group of piles are studied by means of (i) large-scale laboratory tests carried out in the Large Wave Flume (GWK) of the Coastal Research Centre (FZK) in Hannover, and (ii) small scale experiments performed in 2 m-wide wave flume of Leichtweiss-Institute for Hydraulic Engineering and Water Resources (LWI), in Braunschweig, Germany. The small scale model tests (LWI) were scaled down (1:6.5) by Froude law from the large scale model tests (GWK). Scale and model effects are examined by comparing the results of small and large scale laboratory tests.

scholarly journals BREAKING WAVE KINEMATICS, LOCAL PRESSURES, AND FORCES ON A TRIPOD STRUCTURE

2012 ◽  
Vol 1 (33) ◽  
pp. 71 ◽  
Author(s):  
Arndt Hildebrandt ◽  
Torsten Schlurmann
Keyword(s):  
Wave Front ◽  
Wave Breaking ◽  
Large Scale ◽  
Three Dimensional ◽  
Model Tests ◽  
Scale Model ◽  
Breaking Wave ◽  
Wave Loads ◽  
Large Wave ◽  
The Impact

This paper presents breaking wave loads on a tripod structure from physical model tests and numerical simulations. The large scale model tests (1:12) are described as well as the validation of the three dimensional numerical model by comparison of CFD wave gauge data and pressures with measurements in the large wave flume inside and outside the impact area. Subsequently, the impact areas due to a broken wave, a curled wave front as well as for wave breaking directly at the structure with a partly vertical wave front are compared to each other. Line forces in terms of slamming coefficients with variation in time and space are derived from CFD results and the velocity distribution is presented at the onset of wave breaking. Finally, the results are briefly discussed in comparison to other slamming studies.

Coupled Mooring Analysis and Large Scale Model Tests on a Deepwater Calm Buoy in Mild Wave Conditions

2002 ◽  
Author(s):  
T. H. J. Bunnik ◽  
G. de Boer ◽  
J. L. Cozijn ◽  
J. van der Cammen ◽  
E. van Haaften ◽  
...  
Keyword(s):  
Model Tests ◽  
Irregular Waves ◽  
Scale Model ◽  
Mooring Line ◽  
Wave Forces ◽  
Mooring System ◽  
Mooring Lines ◽  
Pitch Moment ◽  
Numerical Tool ◽  
Decay Tests

This paper describes a series of model tests aimed at gaining insight in the tension variations in the export risers and mooring lines of a CALM buoy. The test result were therefore not only analysed carefully, but were also used as input and to validate a numerical tool that computes the coupled motions of the buoy and its mooring system. The tests were carried out at a model scale of 1 to 20. Captive tests in regular and irregular waves were carried out to investigate non-linearities in the wave forces on the buoy for example from the presence of the skirt. Decay tests were carried out to determine the damping of the buoy’s motions and to obtain the natural periods. Finally, tests in irregular waves were carried out. The dynamics of the mooring system and the resulting damping have a significant effect on the buoy’s motions. A numerical tool has been developed that combines the wave-frequency buoy motions with the dynamical behaviour of the mooring system. The motions of the buoy are computed with a linearised equation of motion. The non-linear motions of the mooring system are computed simultaneously and interact with the buoy’s motions. In this paper, a comparison is shown between the measurements and the simulations. Firstly, the wave forces obtained with a linear diffraction computation with a simplified skirt are compared with the measured wave forces. Secondly, the numerical modelling of the mooring system is checked by comparing line tensions when the buoy moves with the motion as measured in an irregular wave test. Thirdly, the decay tests are simulated to investigate the correctness of the applied viscous damping values. Finally, simulations of a test in irregular waves are shown to validate the entire integrated concept. The results show that: 1. The wave-exciting surge and heave forces can be predicted well with linear diffraction theory. However, differences between the measured and computed pitch moment are found, caused by a simplified modelling of the skirt and the shortcomings of the diffraction model. 2. To predict the tension variations in the mooring lines and risers (and estimate fatigue) it is essential that mooring line dynamics are taken into account. 3. The heave motions of the buoy are predicted well. 4. The surge motions of the buoy are predicted reasonably well. 5. The pitch motions are wrongly predicted.

Large-Scale Investigations of Geotextile Sandcontainers Used for Scour Protection of Offshore Monopiles Supporting Wind Energy Turbines

2006 ◽  
Author(s):  
Joachim Gru¨ne ◽  
Uwe Sparboom ◽  
Reinold Schmidt-Koppenhagen ◽  
Zeya Wang ◽  
Hocine Oumeraci
Keyword(s):  
Large Scale ◽  
Research Programme ◽  
Scale Model ◽  
Research Centre ◽  
Large Wave ◽  
Wave Channel ◽  
Large Scale Model ◽  
First Results ◽  
The Stability ◽  
Scour Protection

An innovative scour protection for monopile structures was proposed by using geotextile sand containers in a research programme started recently. Large-scale model tests on the stability of such alternative scour protection are being performed in the Large Wave Channel (GWK) of the Coastal Research Centre (FZK). First results are reported from basic test series performed with single geotextile sand containers and container groups with different container weights, varied in sizes and percentages of filling. Further an empirical approach on the stability of sand containers is estimated as a first approximation from the results.

scholarly journals ON THE BEHAVIOR OF ARMOR UNIT IN THE COVERLAYER

1986 ◽  
Vol 1 (20) ◽  
pp. 157
Author(s):  
Hans Werner Pertenscky ◽  
John Rutte ◽  
Reinold Schmidt
Keyword(s):  
Large Scale ◽  
Standardized Test ◽  
Model Tests ◽  
Scale Model ◽  
Test Procedures ◽  
Long Term Stability ◽  
Number Of Factors ◽  
The Stability ◽  
The Individual

As a result of the large-scale failure of the rubblemound breakwater at SINES, Portugal in 1978 a number of research programs were begun. At present, however, very little information is available from technical publications regarding new design criteria, recommendations, or test procedures for model tests of rubblemound breakwaters. The need still exists, therefore, for economically practical model tests and standardized test procedures so that more tests can be conducted and reproducible results from different institutions can be compared. At the same time, a number of factors related to the stability of rubblemound surface elements, and the interrelationships between those factors, have not been adequately examined or explained. Apparently without extensive model tests, for example, it has been suggested that greater stability can be obtained by using elements with greater unit weights (comparing elements of the same absolute weight) , either by adding scrap metal or denser materials, such as granite, to the concrete. Furthermore, susceptibility to breakage is of major importance to the long-term stability of armour layer units, particularly for dolos and similar less massive element types. This aspect has been generally neglected in laboratory tests, however, and attempts to simulate the lower ultimate strength of elements in reduced-scale model tests appear extremely difficult, as well as costly in terms of time and materials. Several other factors which can significantly affect the stability of an armour layer include the surface roughness of the individual elements, as well as boundary conditions such as the beach slope.

Large scale model tests on Royal Schelde SES

1989 ◽  
Author(s):  
R. DE GAAIJ ◽  
E. VAN RIETBERGEN ◽  
M. SLEGERS
Keyword(s):  
Large Scale ◽  
Model Tests ◽  
Scale Model ◽  
Large Scale Model

Experimental Assessment of the Performance of CECO Wave Energy Converter in Irregular Waves

2018 ◽  
Author(s):  
Claudio A. Rodríguez ◽  
F. Taveira-Pinto ◽  
P. Rosa-Santos
Keyword(s):  
Wave Energy ◽  
Transfer Functions ◽  
Nonlinear Effects ◽  
Model Tests ◽  
Experimental Results ◽  
Irregular Waves ◽  
Scale Model ◽  
Experimental Assessment ◽  
Simplified Approach ◽  
Wave Basin

A new concept of wave energy device (CECO) has been proposed and developed at the Hydraulics, Water Resources and Environment Division of the Faculty of Engineering of the University of Porto (FEUP). In a first stage, the proof of concept was performed through physical model tests at the wave basin (Rosa-Santos et al., 2015). These experimental results demonstrated the feasibility of the concept to harness wave energy and provided a preliminary assessment of its performance. Later, an extensive experimental campaign was conducted with an enhanced 1:20 scale model of CECO under regular and irregular long and short-crested waves (Marinheiro et al., 2015). An electric PTO system with adjustable damping levels was also installed on CECO as a mechanism of quantification of the WEC power. The results of regular waves tests have been used to validate a numerical model to gain insight into different potential configurations of CECO and its performance (López et al., 2017a,b). This paper presents the results and analyses of the model tests in irregular waves. A simplified approach based on spectral analyses of the WEC motions is presented as a means of experimental assessment of the damping level of the PTO mechanism and its effect on the WEC power absorption. Transfer functions are also computed to identify nonlinear effects associated to higher waves and to characterize the range of periods where wave absorption is maximized. Furthermore, based on the comparison of the present experimental results with those corresponding to a linear numerical potential model, some discussions are addressed regarding viscous and other nonlinear effects on CECO performance.

Sign in / Sign up

Export Citation Format

Share Document