Effect of RANS-based turbulence models on nonlinear wave generation in a two-phase numerical wave tank

2017 ◽  
Vol 17 (3) ◽  
pp. 141 ◽  
Author(s):  
Ahmed Elhanafi ◽  
Alan Fleming ◽  
Zhi Leong ◽  
Gregor Macfarlane
Keyword(s):  
Nonlinear Wave ◽  
Turbulence Models ◽  
Wave Generation ◽  
Numerical Wave Tank ◽  
Two Phase ◽  
Wave Tank ◽  
Numerical Wave

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

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.

Numerical Wave Tank Including a Fixed Vertical Cylinder Subjected to Waves, Towards the Investigation of Floating Offshore Wind Turbine Hydrodynamics

2020 ◽  
Author(s):  
Constance Clément ◽  
Pauline Bozonnet ◽  
Guillaume Vinay ◽  
Adria Borras Nadal ◽  
Philippe Pagnier ◽  
...  
Keyword(s):  
Turbulence Model ◽  
Wave Generation ◽  
Hydrodynamic Forces ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Numerical Wave Tank ◽  
Time Step ◽  
Cfd Simulations ◽  
Wave Tank ◽  
Numerical Wave

Abstract Specific engineering tools are used to design Floating Offshore Wind Turbines (FOWT). These so-called aero-hydro-servo-elastic solvers simulate the coupled behaviour of the turbine subjected to wind with the floater motion due to waves, including elasticity of the whole structure. The implemented hydrodynamic forces rely on a strong Oil&Gas background and include potential flow theory and empirical laws, such as Morison forces. The undergoing study aims at re-evaluating the validity range of such theories, when applied to FOWT. To do so, CFD simulations will be run to model wave propagation and interaction with a FOWT floater. Hydrodynamic forces will be extracted from the CFD simulations and compared to current hydrodynamic theories. A fixed cylinder in regular second order deep water waves (steepness of 0.9) is simulated and results are validated against experiments [1]. This basic first case implemented with Open-FOAM using waves2Foam library allows to master regular wave generation and interaction with a rather simple structure, running multiple simulations. Convergence (mesh refinement, time step) and parameterization (numerical schemes, turbulence models) studies are carried out to ensure controlled wave generation. An accurate Numerical Wave Tank (NWT) is finally obtained. However, the resolution of air/water interface with Volume Of Fluid (VOF) MULES method seems to be responsible for extreme air velocities on crests resulting in wave damping. This phenomena is solved by decreasing time step. Hydrodynamic forces on the cylinder match experiments with an error below 3%. As the flow is turbulent (Re = 105), a turbulence model is included in the simulation giving results rather close to the ones obtained without turbulence model.

scholarly journals Generation and Absorption of Periodic Waves Traveling on a Uniform Current in a Fully Nonlinear BEM-based Numerical Wave Tank

2020 ◽  
Vol 8 (9) ◽  
pp. 727
Author(s):  
Dimitris I. Manolas ◽  
Vasilis A. Riziotis ◽  
Spyros G. Voutsinas
Keyword(s):  
Wave Generation ◽  
Periodic Waves ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Fully Nonlinear ◽  
Outflow Boundary Condition ◽  
Feedback Error ◽  
Uniform Current ◽  
Numerical Wave ◽  
Outflow Boundary

Accurate and efficient numerical wave generation and absorption of two-dimensional nonlinear periodic waves traveling on a steady, uniform current were carried out in a potential, fully nonlinear numerical wave tank. The solver is based on the Βoundary Εlement Μethod (ΒΕΜ) with linear singularity distributions and plane elements and on the mixed Eulerian–Lagrangian formulation of the free surface equations. Wave generation is implemented along the inflow boundary by imposing the stream function wave solution, while wave absorption at both end-boundaries is effectively treated by introducing absorbing layers. On the absorbing beach side, the outflow boundary condition is modified to ensure that the solution accurately satisfies the dispersion relation of the generated waves. The modification involves a free-parameter that depends on the mass flux through the domain and is determined through a feedback error-correction loop. The developed method provides accurate time domain wave solutions for shallow, intermediate, and deep water depths of high wave steepness (wave heights up to 80% of the maximum value) that remain stable for 150 wave periods. This also holds in case a coplanar or opposing uniform current of velocity up to 20% of the wave celerity interacts with the wave.

scholarly journals Analysis of Different Methods for Wave Generation and Absorption in a CFD-Based Numerical Wave Tank

2018 ◽  
Vol 6 (2) ◽  
pp. 73 ◽  
Author(s):  
Adria Miquel ◽  
Arun Kamath ◽  
Mayilvahanan Alagan Chella ◽  
Renata Archetti ◽  
Hans Bihs
Keyword(s):  
Wave Generation ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Numerical Wave

The Analysis and Application of Numerical Wave Tank Based on the Viscous Fluid

2010 ◽  
Author(s):  
Lei Yue ◽  
Zhiguo Zhang ◽  
Dakui Feng
Keyword(s):  
Three Dimensional ◽  
Wave Generation ◽  
Green Water ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Water On Deck ◽  
Impact Forces ◽  
Numerical Wave ◽  
The Impact ◽  
Shipping Water

The so-called numerical wave tank is to use a mathematical model to simulate the process of making waves and interaction between waves and structures. Shipping water occurs when the wave height exceeds the deck level of a floating vessel. A large amount of seawater flows down onto the deck. It damages deck equipment and causes even submergence. The water on deck is called “Green Water”, and it is dangerous for ships. It is of great significance to analyze and simulate wave and green water phenomenon. This paper developed a three-dimensional numerical wave tank and presented VOF method to deal with the movement with free surface, and then simulated process of wave generation numerically. A two-dimensional numerical simulation of the green water phenomenon of a hull placed in regular wave was performed. The process of wave running up and wave deforming were obtained. The results show that the present numerical scheme and methods can be used to simulate process of wave generation and phenomenon of green water on deck, and to predict and analyze the impact forces between waves and structures due to green water.

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