Validation of Numerical Wave Tank Simulations Using Reef3d With Jonswap Spectra in Intermediate Water Depth

2005 ◽

Cited By ~ 1

Author(s):

Tim Bunnik ◽

Rene´ Huijsmans

Keyword(s):

Shallow Water ◽

Model Test ◽

Water Depth ◽

Linear Potential ◽

Intermediate Water ◽

Numerical Wave Tank ◽

Wave Tank ◽

Type Wave ◽

Wave Generator ◽

Numerical Wave

During the last few years there has been a strong growth in the availability and capabilities of numerical wave tanks. In order to assess the accuracy of such methods, a validation study was carried out. The study focuses on two types of numerical wave tanks: 1. A numerical wave tank based a non-linear potential flow algorithm. 2. A numerical wave tank based on a Volume of Fluid algorithm. The first algorithm uses a structured grid with triangular elements and a surface tracking technique. The second algorithm uses a structured, Cartesian grid and a surface capturing technique. Validation material is available by means of waves measured at multiple locations in two different model test basins. The first method is capable of generating waves up to the break limit. Wave absorption is therefore modeled by means of a numerical beach and not by mean of the parabolic beach that is used in the model basin. The second method is capable of modeling wave breaking. Therefore, the parabolic beach in the model test basin can be modeled and has also been included. Energy dissipation therefore takes place according to physics which are more related to the situation in the model test basin. Three types of waves are generated in the model test basin and in the numerical wave tanks. All these waves are generated on basin scale. The following waves are considered: 1. A scaled 100-year North-Sea wave (Hs = 0.24 meters, Tp = 2.0 seconds) in deep water (5 meters). 2. A scaled operational wave (Hs = 0.086 meters, Tp = 1.69 seconds) at intermediate water depth (0.86 meters) generated by a flap-type wave generator. 3. A scaled operational wave (Hs = 0.046 meters, Tp = 1.2 seconds) in shallow water (0.35 meters) generated by a piston-type wave generator. The waves are generated by means of a flap or piston-type wave generator. The motions of the wave generator in the simulations (either rotational or translational) are identical to the motions in the model test basin. Furthermore, in the simulations with intermediate water depth, the non-flat contour of the basin bottom (ramp) is accurately modeled. A comparison is made between the measured and computed wave elevation at several locations in the basin. The comparison focuses on: 1. Reflection characteristics of the model test basin and the numerical wave tanks. 2. The accuracy in the prediction of steep waves. 3. Second order effects like set-down in intermediate and shallow water depth. Furthermore, a convergence study is presented to check the grid independence of the wave tank predictions.

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Validation of Numerical Wave Tank Simulations Using REEF3D With JONSWAP Spectra in Intermediate Water Depth

Volume 1: Offshore Technology ◽

10.1115/omae2020-18298 ◽

2020 ◽

Author(s):

Csaba Pakozdi ◽

Sebastien Fouques ◽

Maxime Thys ◽

Arun Kamath ◽

Weizhi Wang ◽

...

Keyword(s):

Test Data ◽

Model Test ◽

Water Depth ◽

Model Tests ◽

Irregular Waves ◽

Wave Crest ◽

Intermediate Water ◽

Numerical Wave Tank ◽

Wave Tank ◽

Numerical Wave

Abstract As offshore wind turbines increase in size and output, the support structures are also growing. More sophisticated assessment of the hydrodynamic loads is needed, particularly for the ultimate limit state design. For higher-order phenomena related to rare steep wave events such as ringing, a better understanding of the stochastic loads is needed. As an innovative step forward to reduce the cost of extensive model tests with irregular waves, a larger number of investigations can be carried out using high-performance high-fidelity numerical simulations after an initial stochastic validation with model test data. In this paper, the open-source hydrodynamic model REEF3D::FNPF (Fully Nonlinear Potential Flow) is used to carry out three-hour long simulations with the JONSWAP spectrum in intermediate water depth conditions. Statistical properties of the free surface elevation in the numerical wave tank are validated using the available data from model tests carried out at SINTEF Ocean/NTNU. The spectral shape, significant wave height, peak period, skewness, kurtosis, and wave crest height statistics are compared. The results are analyzed and it is found that the numerical model provides reasonably good agreement with the model test data.

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Design of a Numerical Wave Tank and Wave Flume for Low Steepness Waves in Deep and Intermediate Water

Procedia Engineering ◽

10.1016/j.proeng.2015.08.394 ◽

2015 ◽

Vol 116 ◽

pp. 221-228 ◽

Cited By ~ 8

Author(s):

Shaswat Saincher ◽

Jyotirmay Banerjeea

Keyword(s):

Intermediate Water ◽

Numerical Wave Tank ◽

Wave Tank ◽

Wave Flume ◽

Numerical Wave

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Numerical and Experimental Studies on a Three-Dimensional Numerical Wave Tank

IEEE Access ◽

10.1109/access.2018.2794064 ◽

2018 ◽

Vol 6 ◽

pp. 6585-6593 ◽

Cited By ~ 7

Author(s):

Xiaojie Tian ◽

Qingyang Wang ◽

Guijie Liu ◽

Wei Deng ◽

Zhiming Gao

Keyword(s):

Experimental Studies ◽

Three Dimensional ◽

Numerical Wave Tank ◽

Wave Tank ◽

Numerical Wave

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Numerical Investigation of Focused Waves and Their Interaction With a Vertical Cylinder Using REEF3D

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4036206 ◽

2017 ◽

Vol 139 (4) ◽

Cited By ~ 15

Author(s):

Hans Bihs ◽

Mayilvahanan Alagan Chella ◽

Arun Kamath ◽

Øivind Asgeir Arntsen

Keyword(s):

Free Surface ◽

Stokes Equations ◽

Free Surface Flows ◽

Surface Elevation ◽

Numerical Wave Tank ◽

Free Surface Elevation ◽

Wave Tank ◽

Numerical Wave ◽

Focused Wave ◽

The Impact

For the stability of offshore structures, such as offshore wind foundations, extreme wave conditions need to be taken into account. Waves from extreme events are critical from the design perspective. In a numerical wave tank, extreme waves can be modeled using focused waves. Here, linear waves are generated from a wave spectrum. The wave crests of the generated waves coincide at a preselected location and time. Focused wave generation is implemented in the numerical wave tank module of REEF3D, which has been extensively and successfully tested for various wave hydrodynamics and wave–structure interaction problems in particular and for free surface flows in general. The open-source computational fluid dynamics (CFD) code REEF3D solves the three-dimensional Navier–Stokes equations on a staggered Cartesian grid. Higher order numerical schemes are used for time and spatial discretization. For the interface capturing, the level set method is selected. In order to test the generated waves, the time series of the free surface elevation are compared with experimental benchmark cases. The numerically simulated free surface elevation shows good agreement with experimental data. In further computations, the impact of the focused waves on a vertical circular cylinder is investigated. A breaking focused wave is simulated and the associated kinematics is investigated. Free surface flow features during the interaction of nonbreaking focused waves with a cylinder and during the breaking process of a focused wave are also investigated along with the numerically captured free surface.

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