Prediction of Wave Crest and Height Distributions and Wave Groups Using a Numerical Wave Tank

2010 ◽  
Author(s):  
Christian Schmittner ◽  
Sascha Kosleck ◽  
Janou Hennig
Keyword(s):  
Current Model ◽  
Power Spectra ◽  
Distribution Functions ◽  
Wave Crest ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Wave Measurements ◽  
Starting Point ◽  
Wave Basin ◽  
Numerical Wave

A major goal in current model test practice is the correct modeling of the environmental conditions, as they denote the starting point for all further hydrodynamic analyses. As a standard, wave power spectra are calibrated prior to the actual model tests whereas the corresponding wave group spectra follow from the arbitrarily chosen wave seeds and are not being predicted in advance. Wave crest and height distributions can be determined from the measured wave time traces at different reference locations in the basin but they are not calibrated purposely either. In this paper, a numerical wave tank based on a boundary element method is used to predict wave time traces measured in the wave basin. Resulting wave crest and height distributions are compared with theoretical distribution functions and wave measurements in MARIN’s Offshore Basin. Some thoughts on a possible application to the generation of “deterministic wave seeds” conclude the paper.

Effect of Variations in Calibrated Wave Parameters on Wave Crest and Height Distributions

2010 ◽  
Author(s):  
Janou Hennig ◽  
Jule Scharnke
Keyword(s):  
Power Spectra ◽  
Distribution Functions ◽  
Wave Crest ◽  
Wave Power ◽  
Wave Group ◽  
Wave Measurements ◽  
Initial Wave ◽  
Alternative Approach ◽  
Wave Basin ◽  
Wave Trains

In common model test practice, wave power spectra are calibrated prior to the actual model tests. The resulting wave crest and height distributions can be determined from the measured wave time traces at different reference location in the basin but they are not calibrated purposely. The corresponding wave group spectra follow from the wave power spectra together with arbitrarily chosen wave seeds applied to the wave trains. As an alternative approach, the seeds which give the highest and lowest wave group spectra can be applied in the tests. In this paper, results of wave measurements in MARIN’s Shallow Water Basin are presented which include a variation in water depth, wave seed (group spectrum) and location of measurement for the same initial wave power spectrum. The resulting wave crest and height distributions at different wave basin locations are analyzed and compared to theoretical distribution functions. A discussion of possible reasons for differences between theory and measurement concludes the investigation.

scholarly journals An Efficient 3-D FNPF Numerical Wave Tank for Virtual Large-Scale Wave Basin Experiment

2012 ◽  
Author(s):  
Seshu Nimmala ◽  
Solomon Yim ◽  
Stephan Grilli
Keyword(s):  
High Performance ◽  
Large Scale ◽  
Mathematical Formulation ◽  
Three Dimensional ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Wave Basin ◽  
Nonlinear Potential ◽  
Numerical Wave ◽  
Computing Platforms

This paper presents an accurate and efficient three-dimensional computational model (3D numerical wave tank), based on fully nonlinear potential flow (FNPF) theory, and its extension to incorporate the motion of a laboratory snake piston wavemaker, to simulate experiments in a large-scale 3D wave basin (i.e. to conduct “virtual” or numerical experiments). The code is based on a higher-order boundary element method combined with a Fast Multipole Algorithm (FMA). Particular efforts were devoted to making the code efficient for large-scale simulations using high-performance computing platforms to complement experimental 3D wave basins. The numerical simulation capability can serve as an optimization tool at the experimental planning and detailed design stages. To date, waves that can be generated in the NWT include solitary, Cnoidal, and Airy waves. In this paper, we detail the model, mathematical formulation, and wave generation. Experimental or analytical comparisons with NWT results are provided for several cases to assess the accuracy and applicability of the numerical model to practical engineering problems.

scholarly journals Generation of Offshore Environments in the Numerical Wave Tank to Model Metocean Conditions Interaction with Offshore Structure Near the Free Surface

2021 ◽  
Vol 945 (1) ◽  
pp. 012018
Author(s):  
Mushtaq Ahmed ◽  
Zafarullah Nizamani ◽  
Akihiko Nakayama ◽  
Montasir Osman
Keyword(s):  
Free Surface ◽  
Offshore Structures ◽  
Operating Conditions ◽  
Wave Crest ◽  
Extreme Conditions ◽  
Numerical Wave Tank ◽  
Offshore Structure ◽  
Wave Tank ◽  
Numerical Wave ◽  
Operating Wave

Abstract Offshore structures play a vital role in the economy of offshore oil-producing countries, where mostly fixed jacket type structures are used to produce oil and gas installed in shallow water. In an offshore environment where structures are installed, there exist met ocean forces such as wind, waves, and currents. These met ocean conditions when interacting with offshore structures near the free surface, generate loads. The estimation of such loads is very much important for the proper design of these structures. The primary aim of this study is to investigate the interaction of waves with a jacket platform by generating offshore environments in the numerical wave tank (NWT). To achieve this goal, ANSYS Fluent is used for the flow analysis by using continuity and Navier Stokes equation. Results are verified and validated with the analytical work. Wave crests under operating condition generate a force of 1.3 MN which is the lowest in magnitude as compared to wave crest which produces 4.5 MN force under extreme conditions. Unlike operating wave crest, the operating wave trough generates a higher force of 1 MN than extreme conditions which account for 1.5 MN forces. Forces produced by the extreme offshore environment are 30% higher than those generated under operating conditions. It is concluded from the results that a positive force is exerted onto the structure during the water entry phase while a negative force is observed when the water leaves the structure.

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

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.

Fully Nonlinear Multidirectional Waves by a 3-D Viscous Numerical Wave Tank

2001 ◽  
Vol 123 (3) ◽  
pp. 124-133 ◽  
Author(s):  
M. H. Kim ◽  
J. M. Niedzwecki ◽  
J. M. Roesset ◽  
J. C. Park ◽  
S. Y. Hong ◽  
...  
Keyword(s):  
Finite Difference ◽  
Side Wall ◽  
Function Technique ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Fully Nonlinear ◽  
Wave Basin ◽  
Fluid Layers ◽  
Numerical Wave ◽  
Two Fluid

A finite-difference scheme and a modified marker-and-cell (MAC) method are used for numerical wave tank (NWT) simulations to investigate the characteristics of nonlinear multidirectional waves. The Navier-Stokes (NS) equations are solved for two fluid layers and the boundary values updated at each time step by a finite-difference time-marching scheme in the frame of rectangular coordinate system. The fully nonlinear kinematic free-surface condition is satisfied by the density-function technique developed for two fluid layers. The directional incident waves are generated from the inflow boundary by prescribing a snakelike motion along the wavemaker direction. The outgoing waves are numerically dissipated inside an artificial damping zone located at the end of the tank. Using the NS-MAC NWT with both solid and transparent side-wall conditions, the effects of side-wall reflections are studied. Bull’s-eye waves are also numerically generated by the phase control of neighboring wavemaker segments or the reverse process of cylindrical wavemakers. The simulation results are compared with the computations by an independently developed potential-based NWT and the experiments conducted in the Offshore Technology Research Center’s 3-D wave basin.

An Efficient Three-Dimensional FNPF Numerical Wave Tank for Large-Scale Wave Basin Experiment Simulation

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Seshu B. Nimmala ◽  
Solomon C. Yim ◽  
Stephan T. Grilli
Keyword(s):  
High Performance ◽  
Large Scale ◽  
Parallel Implementation ◽  
Mathematical Formulation ◽  
Three Dimensional ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Wave Basin ◽  
Numerical Wave ◽  
Computing Platforms

This paper presents a parallel implementation and validation of an accurate and efficient three-dimensional computational model (3D numerical wave tank), based on fully nonlinear potential flow (FNPF) theory, and its extension to incorporate the motion of a laboratory snake piston wavemaker, as well as an absorbing beach, to simulate experiments in a large-scale 3D wave basin. This work is part of a long-term effort to develop a “virtual” computational wave basin to facilitate and complement large-scale physical wave-basin experiments. The code is based on a higher-order boundary-element method combined with a fast multipole algorithm (FMA). Particular efforts were devoted to making the code efficient for large-scale simulations using high-performance computing platforms. The numerical simulation capability can be tailored to serve as an optimization tool at the planning and detailed design stages of large-scale experiments at a specific basin by duplicating its exact physical and algorithmic features. To date, waves that can be generated in the numerical wave tank (NWT) include solitary, cnoidal, and airy waves. In this paper we detail the wave-basin model, mathematical formulation, wave generation, and analyze the performance of the parallelized FNPF-BEM-FMA code as a function of numerical parameters. Experimental or analytical comparisons with NWT results are provided for several cases to assess the accuracy and applicability of the numerical model to practical engineering problems.

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

IEEE Access ◽  
2018 ◽  
Vol 6 ◽  
pp. 6585-6593 ◽  
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

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

2017 ◽  
Vol 139 (4) ◽  
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.

MOTION OF FLOATING CAISSON USING 3D NUMERICAL WAVE TANK

2021 ◽  
Vol 77 (2) ◽  
pp. I_775-I_780
Author(s):  
Atsushi TAKAGI ◽  
Masashi WATANABE ◽  
Taro ARIKAWA
Keyword(s):  
Numerical Wave Tank ◽  
Wave Tank ◽  
Numerical Wave

Numerical simulation of regular waves: Optimization of a numerical wave tank

2018 ◽  
Vol 170 ◽  
pp. 89-99 ◽  
Author(s):  
Fábio M. Marques Machado ◽  
António M. Gameiro Lopes ◽  
Almerindo D. Ferreira
Keyword(s):  
Numerical Simulation ◽  
Numerical Wave Tank ◽  
Regular Waves ◽  
Wave Tank ◽  
Numerical Wave
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