scholarly journals REPRODUCTION MODELS OF BEACH CHANGE BY STORM WAVES

1988 ◽  
Vol 1 (21) ◽  
pp. 115
Author(s):  
Masahiro Ito ◽  
Yoshito Tsuchiya
Keyword(s):  
Grain Size ◽  
Model Test ◽  
Irregular Waves ◽  
Scale Model ◽  
Regular Waves ◽  
Wave Duration ◽  
Storm Waves ◽  
The Mean ◽  
Wave Properties ◽  
Sand Grain Size

This paper presents a technique to reproduce, by a twodimensional moveable-bed model, beach change due to the timedependent storm waves which are generated by the passage of an atmospheric depression. In the model test, scaling conditions for sand grain-size, vertical and horizontal lengths, and wave height and period characteristics were established by applying the authors' scale-model relationship which was reported; and wave duration time also was decided. A method of employing regular waves in the model to represent irregular waves in the field is proposed. From the results, it was shown that the model can reproduce well the beach change in the field using the regular waves having the mean wave properties in the irregular waves.

Large scale model test investigation on wave run-up in irregular waves at slender piles

2013 ◽  
Vol 72 ◽  
pp. 69-79 ◽  
Author(s):  
J. Ramirez ◽  
P. Frigaard ◽  
T. Lykke Andersen ◽  
L. de Vos
Keyword(s):  
Model Test ◽  
Large Scale ◽  
Irregular Waves ◽  
Scale Model ◽  
Large Scale Model ◽  
Test Investigation ◽  
Run Up

Experimental Study on Hydrodynamics of Hybrid Deep-V Monohull With Different Built-Up Appendages

2018 ◽  
Author(s):  
Shuzheng Sun ◽  
Hui Li ◽  
Muk Chen Ong
Keyword(s):  
Model Test ◽  
Performance Model ◽  
Hydrodynamic Performance ◽  
Irregular Waves ◽  
Hydrodynamic Characteristics ◽  
Vertical Acceleration ◽  
Test Results ◽  
Regular Waves ◽  
Sea State ◽  
Seakeeping Performance

The hydrodynamic characteristics of a hybrid deep-V monohull with different built-up appendages are investigated experimentally in order to improve the resistance and seakeeping performance. Model tests have been carried out to study the hydrodynamic performance between a bare deep-V vessel and a deep-V monohull with different built-up appendage configurations (i.e. a hybrid deep-V monohull). From the model test results, it is found that the existence of the appendages will reduce the amplitude of pitching angle and bow vertical acceleration compared to that of the bare deep-V vessel in heading regular waves. However, the resistances for the hybrid deep-V monohull with built-up appendages are increased 15.6% for Fn = 0.264, and 0.1% for Fn = 0.441 compared to the resistance of the bare deep-V vessel. The model test results of seakeeping performance in irregular waves show that the hybrid deep-V monohull gives a better seakeeping performance than the deep-V vessel. The pitching angle and bow vertical acceleration of the hybrid deep-V monohull containing a built-up appendage are reduced 15.3% and 20.6% compared to the deep-V monohull in irregular waves at Fn = 0.441 in 6th class sea state (H1/3 = 6m).

Behaviour of a Suspended Wellbay Module and Flare Tower in Waves During Transit to Shore

2019 ◽  
Author(s):  
Hoi-Sang Chan ◽  
Evren Armaoğlu ◽  
Matthew Thomson ◽  
Alistair Garner
Keyword(s):  
Frequency Domain ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Irregular Waves ◽  
Scale Model ◽  
Response Analysis ◽  
Regular Waves ◽  
The North ◽  
Response Amplitude Operators

Abstract The extended lift operation to deliver the Wellbay module (M5) combined with the Flare Tower (M8) from the Miller Platform in the North Sea to the shore using the Semi-Submersible Crane Vessel S7000 was restricted by the clearances between M5/M8 and the vessel crane booms. A method to calculate the clearances of the M5/M8 normal to the vessel crane booms has been developed and used in a frequency-domain response analysis to define operability limits. Investigations based on a series of scale model tests in regular waves and irregular short-crested waves including motion decay tests in calm water, conducted by the Maritime Research Institute (MARIN) in the Netherlands, were also made to further evaluate the behaviour of the suspended M5/M8 on S7000’s main hooks during transit. The time series of decay motions of the suspended M5/M8 obtained from the decay motion tests and a time domain analysis are compared and used to derive rigging damping. The numerical results of the frequency-domain analysis are validated with the experimental data for response amplitude operators (RAOs) found in regular waves and pink noise waves, significant and 3 hour most probable maximum/minimum (MPM) responses of interest in irregular waves.

scholarly journals APPLICATIONS OF A NUMERICAL SHALLOW WATER WAVES MODEL

1982 ◽  
Vol 1 (18) ◽  
pp. 54
Author(s):  
A. Hauguel ◽  
Ph. Pechon
Keyword(s):  
Numerical Model ◽  
Water Waves ◽  
Breaking Waves ◽  
Scale Model ◽  
Dimensional Model ◽  
Longshore Current ◽  
Shallow Water Waves ◽  
Storm Waves ◽  
Mean Sea Surface ◽  
The Mean

This paper relates three applications of a numerical model of storm waves in shallow waters developed in LNH. The equations are recalled at first and then the applications performed are presented. The numerical model has been used in the case of the port of Fecamp, on the English Channel coast, on which the results of a scale model were available. The computed results compare well with the scale model measurements. The second case is the s imulation of a t sumami induced by a submarine landslide which appeared in 1979 near Nice ; the mode 1 has permitted the simulation of the rising of the wave. The last applications consisted in simulating breaking waves by introducing a dispersion term in the equations. This simulation has been tested with a one-dimensional model at first. The results show that the numerical model reproduces the elevation of the mean sea surface due to the loss of energy in breakings. Then the longshore current induced by breaking waves coming obliquely over a rectilinear sloping shore has been reproduced with a two dimensional model. The results show that the model is able to compute with a good accuracy re fraction, diffraction and reflection, and that it appears to be very interesting for longshore currents simulation.

scholarly journals Experimental and Numerical Analysis of a 10 MW Floating Offshore Wind Turbine in Regular Waves

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2608
Author(s):  
Hyeonjeong Ahn ◽  
Hyunkyoung Shin
Keyword(s):  
Wind Turbine ◽  
Model Test ◽  
Model Tests ◽  
Offshore Wind ◽  
East Sea ◽  
Irregular Waves ◽  
Offshore Wind Turbine ◽  
Regular Waves ◽  
Floating Offshore Wind Turbine ◽  
Floating Offshore Wind Turbines

Floating offshore wind turbines (FOWTs) experience fluctuations in their platforms, owing to the various wave and wind conditions. These fluctuations not only decrease the output of the wind power generation system, but also increase the fatigue load of the structure and various equipment mounted on it. Therefore, when designing FOWTs, efficient performance with respect to waves and other external conditions must be ensured. In this study, a model test was performed with a 10 MW floating offshore wind turbine. The model test was performed by scaling down a 10 MW FOWT model that was designed with reference to a 5 MW wind turbine and a semisubmersible platform by the National Renewable Energy Laboratory and the DeepCwind project. A scale ratio of 1:90 was used for the model test. The depth of the East Sea was considered as 144 m and, to match the water depth with the geometric similarity of mooring lines, mooring tables were installed. The load cases used in the model test are combined environmental conditions, which are combined uniform wind, regular waves and uniform current. Especially, Model tests with regular waves are especially necessary, because irregular waves are superpositions of regular waves with various periods. Therefore, this study aimed to understand the characteristics of the FOWTs caused by regular waves of various periods. Furthermore, in this model test, the effect of current was investigated using the current data of the East Sea. The results obtained through the model tests were the response amplitude operator (RAO) and the effective RAO for a six degrees-of-freedom motion. The results obtained from the model tests were compared with those obtained using the numerical simulation. The purpose of this paper is to predict the response of the entire system observed in model tests through simulation.

Experimental Investigation of Wave Loads Based on Trimaran Self-Propulsion Model

2016 ◽  
Author(s):  
Wei Xiaobo ◽  
Huilong Ren ◽  
Yanlong Sun ◽  
Di Wang ◽  
Zhen Yu Wang
Keyword(s):  
Model Test ◽  
High Speed ◽  
High Performance ◽  
Similarity Theory ◽  
Scale Model ◽  
Comprehensive Model ◽  
Wave Loads ◽  
Test Results ◽  
Regular Waves ◽  
Test Study

Trimaran, as a high performance ship, its special ship form is different from regular monohull ship. The particular characteristics of longitudinal and transverse wave loads are concerned greatly by ship structure designers. Theoretical methods for forecasting the wave loads of trimaran are under developing. And the relative comprehensive model test study of trimaran’s wave loads is rare in the publication. In this paper, the trimaran model test had been carried out in the tank. According to similarity theory and simulation of stiffness, a scale model of trimaran with measurement system had been manufactured. Then the segmented model had navigated in regular waves of different sea conditions. Through analysis of the experimental data, the wave loads characteristics of this trimaran are presented. A comparison of test results and theoretical values is also made to show the similarities and differences. This study can provide some useful information for further design of high-speed trimaran in the point of wave loads, which maybe a reference for research of trimaran.

Crack Resistance Design for the Circular Hydraulic Tunnel Lining Structures

2014 ◽  
Vol 672-674 ◽  
pp. 1851-1854
Author(s):  
Wei Shen
Keyword(s):  
Crack Resistance ◽  
Model Test ◽  
Crack Width ◽  
Large Scale ◽  
Engineering Application ◽  
Hydroelectric Station ◽  
Scale Model ◽  
Reinforcing Bars ◽  
Lining Structure ◽  
The Mean

In this paper, an indoor large scale model test on the crack resistance of hydraulic tunnel structure which has first adopted the real water load in China was conducted in Dalian University of Technology. The model test can reveal the load carrying capacity and the deformation of the lining structure effectively. Based on the test results, models respectively for the mean crack width and the mean stress of reinforcing bars were developed and then compared with existing monitoring data provided by a hydroelectric station. The results shows that the model for predicting the crack width of lining structure has a good accuracy and thus is of great value in the engineering application.

A STUDY ON VISCOUS ROLL DAMPING OF A BOX-SHAPED VESSEL IN THE FREQUENCY DOMAIN USING THE DISCRETE VORTEX METHOD

2021 ◽  
Vol 153 (A2) ◽  
Author(s):  
M Hajiarab ◽  
M Downie ◽  
M Graham
Keyword(s):  
Frequency Domain ◽  
Model Test ◽  
Wave Amplitude ◽  
Vortex Method ◽  
Model Tests ◽  
Irregular Waves ◽  
Regular Waves ◽  
Roll Damping ◽  
Discrete Vortex ◽  
Discrete Vortex Method

This paper presents a study on viscous roll damping of a floating box-shaped vessel in the frequency domain. The application of the discrete vortex method (DVM) for calculation of the viscous roll damping in regular seas has been validated by model tests. Equivalent roll RAOs associated with a range of regular wave amplitudes are calculated to assess behaviour of the viscous roll damping in relation to incident wave amplitude linearisation. A model test is conducted using the model test facilities of the Marine Hydrodynamics Laboratory at Newcastle University to validate the applicability of the DVM in calculating the roll RAO in regular waves and to study the application of this method to irregular waves. Results of these model tests are presented in this paper.

Evaluation of Response Amplitude Operator of Ship Roll Motions Based on the Experiments in White Noise Waves

2017 ◽  
Author(s):  
Sebastian Bielicki ◽  
Antoni Bednarek ◽  
Marek Kraskowski
Keyword(s):  
White Noise ◽  
Response Amplitude ◽  
Irregular Waves ◽  
Scale Model ◽  
Roll Motion ◽  
Viscous Damping ◽  
Regular Waves ◽  
Irregular Wave ◽  
Decay Test ◽  
Ship Roll

Evaluation of the response amplitude operator (RAO) function for ship wave frequency motions by means of scale model tests in regular waves is a standard procedure conducted by hydrodynamic model testing institutions. The resulting RAO function allows for evaluating sufficiently reliable seakeeping predictions for low to moderate sea states. However, for standard hull forms, correct prediction of roll motion in irregular wave (and also in regular waves different than these used in the experiment) on the basis of RAO function presents a substantial challenge due to considerable contribution of viscous damping to roll response. In other words, the RAO values depend strongly on the amplitude of the waves used in the experiment, so the final prediction requires careful application of relevant correction of RAO, dependent on the actual significant wave height, for which the prediction is computed. Thus, in order to collect complete data for ship roll prediction, the roll decay test is usually also required. Additional drawback of evaluating the seakeeping prediction on the basis of RAO is the fact that the experiment in regular waves is quite time-consuming, which refers to the experiment itself as well as to the processing. The following paper presents a proposal of the alternative method for experimental evaluation of response amplitude operator of roll motion in beam waves, consisting in exposing the ship model to irregular wave characterized by white noise spectrum, i.e. the spectrum of uniform energy density. In theory, RAO function is equivalent to the square root of the spectrum of the response to white noise wave. The results of experiments in white noise waves were verified on the basis of the results of comprehensive experiments conducted in usual way. Additionally, the effect of non-linearity of viscous damping was widely studied by comparing the calibrated RAO-based predictions with actual response to irregular waves of different heights. As a result, a method for including the non-linear effects in prediction based on white noise was proposed. It was proved that the proposed method is capable of providing equally valuable information in significantly shorter time.

Motion of OC4 5MW Semi-Submersible Offshore Wind Turbine in Irregular Waves

2013 ◽  
Author(s):  
Hyunkyoung Shin ◽  
Byungcheol Kim ◽  
Pham Thanh Dam ◽  
Kwangjin Jung
Keyword(s):  
Numerical Analysis ◽  
Wind Turbine ◽  
Model Test ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Scale Model ◽  
Offshore Wind Turbine ◽  
Wind Turbine System ◽  
The World ◽  
Energy Shortage

The interests in new and renewable energies increase sharply while our world suffers from environmental pollution and energy shortage. Governments and organizations throughout the world have tried to develop those energies to reduce pollution and solve energy crisis. In this study, we carry out a 1:80 scale model test and full scale numerical analysis of the OC4 5MW semi-submersible offshore wind turbine system designed by DeepCwind project. The purpose of this model test and numerical analysis is to predict and evaluate its motion in irregular waves.

Sign in / Sign up

Export Citation Format

Share Document