A meshless numerical wave tank for simulation of nonlinear irregular waves in shallow water

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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Development of 3-D Numerical Wave Tank and Applications on Comb-Type Breakwater

29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 6 ◽

10.1115/omae2010-20337 ◽

2010 ◽

Author(s):

Zhuo Fang ◽

Liang Cheng ◽

Ningchuan Zhang

Keyword(s):

Offshore Structures ◽

Wave Generation ◽

Irregular Waves ◽

Secondary Wave ◽

Wave Forces ◽

Numerical Wave Tank ◽

Wave Reflections ◽

Wave Tank ◽

Numerical Wave ◽

Source Wave

In this study, a 3-D numerical wave tank is developed, based on a commercial computational fluid dynamics (CFD) package (FLUENT) to predict wave forces on coastal and offshore structures. A source wave-generation method is introduced to FLUENT through user-defined functions to generate incident waves. Spongy layers are used on both upstream and downstream sides of the wave tank to reduce the effects of wave reflections and secondary wave reflections. Various wave trains, such as linear monochromatic waves, second order Stokes waves and irregular waves were generated by using different source functions. It is demonstrated through numerical examples that the source wave-generation method can accurately generate not only small amplitude waves but also nonlinear waves. The present numerical wave tank is validated against standing waves in front of a vertical breakwater. Interactions between waves and a comb-type breakwater are simulated using the present model. The numerical results are compared with physical experimental results. It is found that the present numerical wave tank simulated the wave and breakwater interactions well.

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A Study on Performance Evaluation of Non-Reflective Boundary for Progressive Waves Reproduction Introduced in Numerical Wave Tank With MPS Method

10.1115/omae2021-62364 ◽

2021 ◽

Author(s):

Yasuhiro Aida ◽

Tomotaka Takeo ◽

Tomoki Ikoma ◽

Koichi Masuda

Keyword(s):

Position Control ◽

Wave Spectrum ◽

Irregular Waves ◽

Finite Width ◽

Water Tank ◽

Numerical Wave Tank ◽

Wave Tank ◽

Reflected Waves ◽

Mps Method ◽

Numerical Wave

Abstract Numerical simulation based on the moving particle semi-implicit (MPS) method is effective for the analysis of floating motion in stormy waves in both coastal and offshore areas. However, when the outer circumference of the calculation area is composed of wall boundaries, superimposed waves are generated by the reflected waves, which makes it difficult to reproduce wave fields in offshore areas. Therefore, in this study, we developed two types of non-reflective boundary that can be applied to a numerical wave tank with the MPS method. One type is an attenuation zone in which a high-viscosity region with a finite width is set from the end of the water tank. The other type is a wave absorption control boundary that detects the amount of water surface fluctuation in front of the boundary and prevents reflection via position control. Regular and irregular waves were created in a numerical wave tank with these boundaries and the wave dissipation performance was quantitatively evaluated by comparing the estimates for incident and reflected waves, the time-series waveform, and the wave spectrum.

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Simulation of irregular waves over submerged obstacle on a NURBS potential numerical wave tank

Latin American Journal of Solids and Structures ◽

10.1590/s1679-78252014001300001 ◽

2014 ◽

Vol 11 (13) ◽

pp. 2308-2332 ◽

Cited By ~ 7

Author(s):

Arash Abbasnia ◽

Mahmoud Ghiasi

Keyword(s):

Irregular Waves ◽

Numerical Wave Tank ◽

Wave Tank ◽

Numerical Wave

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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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Propagation of Fully Nonlinear Waves in Deepwater, Transition Zone and Shallow-Water

Volume 5: Ocean Space Utilization; Polar and Arctic Sciences and Technology; The Robert Dean Symposium on Coastal and Ocean Engineering; Special Symposium on Offshore Renewable Energy ◽

10.1115/omae2007-29398 ◽

2007 ◽

Author(s):

Hoda M. El Safty ◽

Alaa M. Mansour ◽

A. G. Abul-Azm

Keyword(s):

Shallow Water ◽

Transition Zone ◽

Nonlinear Waves ◽

Wave Number ◽

Numerical Wave Tank ◽

Tank Model ◽

Wave Tank ◽

Fully Nonlinear ◽

Nonlinear Solution ◽

Numerical Wave

In this paper, a fully nonlinear numerical wave tank model has been used to simulate the propagation of fully nonlinear waves in different water depths. In the numerical wave tank model, the fully nonlinear dynamic and kinematic free-surface boundary conditions have been applied and the boundary integral equation (BIE) solution to the Laplacian problem has been obtained using the Mixed Eulerian-Lagrangian (MEL) approach. The model solution has been verified through the comparison with the available experimental data. A convergence and accuracy study has been carried out to examine the time stepping scheme and the required mesh density. The nonlinearity effects were evident in the solution by the asymmetrical wave profile around both vertical and horizontal axis along with sharp high crests and broad flat troughs. Fully nonlinear wave propagation in deepwater, in transition zone and in shallow water has been simulated. The nonlinear solution has been compared to the linear solution for various waves. Shoaling coefficient and wave-number have been derived based on the nonlinear solution and compared to the linear theory solution for various wave characteristics.

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Simulation of Irregular Waves in a Numerical Wave Tank

Polish Maritime Research ◽

10.1515/pomr-2015-0027 ◽

2015 ◽

Vol 22 (s1) ◽

pp. 21-25 ◽

Cited By ~ 1

Author(s):

Li Zhi-Fu ◽

Shi YuYun ◽

Ren HuiLonga ◽

Li Hui ◽

Muhammad Aqeel Ashraf

Keyword(s):

Domain Boundary ◽

Surface Condition ◽

Irregular Waves ◽

Open Boundary ◽

Numerical Wave Tank ◽

Wave Tank ◽

Time Marching ◽

Numerical Wave ◽

Wave Energy Spectrum ◽

The Time Domain

Abstract The time domain boundary element method was utilized to simulate the propagation of the irregular waves in a numerical wave tank. The problem was solved in a time-marching scheme, upon the irregular waves being fed through the inflow boundary, in which the theoretical solution was obtained from the wave energy spectrum. The open boundary condition was modeled by the multi transmitting formula (MTF), in which the phase velocity was calculated according to the Sommerfeld’s condition. The velocity potential and wave elevation were directly obtained by integrating the free surface condition twice, with respect to time. The accuracy of the developed numerical scheme was verified by simulating the propagation of irregular waves. The numerical results show good agreements with the analytical solutions, which prove that the proposed scheme is a promising way to the simulation of wave-body interactions.

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