Development and Validation of a DFC-Based Numerical Wave Tank for the Analysis of Wave-Structure Interaction of the Novel REEFS WEC

2021 ◽  
Author(s):  
Daniel Oliveira ◽  
José Paulo Pereira de Gouveia Lopes de Almeida ◽  
Aldina Santiago ◽  
Constança Rigueiro
Keyword(s):  
Wave Structure ◽  
The Novel ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Structure Interaction ◽  
Numerical Wave ◽  
Development And Validation ◽  
Wave Structure Interaction

Wave-Structure Interaction of Focussed Waves With REEF3D

2016 ◽  
Author(s):  
Hans Bihs ◽  
Mayilvahanan Alagan Chella ◽  
Arun Kamath ◽  
Øivind A. Arnsten
Keyword(s):  
Free Surface ◽  
Level Set ◽  
Wave Structure ◽  
High Order ◽  
Navier Stokes ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Structure Interaction ◽  
Numerical Wave ◽  
Wave Structure Interaction

For the stability of offshore structures, such as offshore wind foundations, extreme wave conditions need to be taken into account. Waves from extreme events can become critical from design perspective. In a numerical wave tank, extreme waves can be generated through focussed waves. Here, linear waves are generated from a wave spectrum. The wave crests of the generated waves coincide at a pre-selected location and time. 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 shows good agreement with the measurements from experiments. In further computations, the wave impact of the focussed waves on a vertical circular cylinder is investigated. The focussed 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 CFD code REEF3D solves the three-dimensional Navier-Stokes equations on a staggered Cartesian grid. Solid boundaries are taken into account with the ghost cell immersed boundary method. For the discretization of the convection terms of the momentum equations, the conservative finite difference version of the fifth-order WENO (weighted essentially non-oscillatory) scheme is used. For temporal treatment, the third-order TVD (total variation diminishing) Runge-Kutta scheme is employed. For the pressure, the projection method is used. The free surface flow is solved as two-phase fluid system. For the interface capturing, the level set method is selected. The level set function can be discretized with high-order differencing schemes. This makes it the appropriate solution for wave propagation problems based on Navier-Stokes solvers, which requires high-order numerical methods to avoid artificial wave damping. The numerical model is fully parallelized based on the domain decomposition, using MPI (message passing interface) for internode communication.

scholarly journals Focused waves and wave–structure interaction in a numerical wave tank

2012 ◽  
Vol 45 ◽  
pp. 9-21 ◽  
Author(s):  
J. Westphalen ◽  
D.M. Greaves ◽  
C.J.K. Williams ◽  
A.C. Hunt-Raby ◽  
J. Zang
Keyword(s):  
Wave Structure ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Structure Interaction ◽  
Numerical Wave ◽  
Wave Structure Interaction

Development of 3-Dimensional Fully Nonlinear Potential Flow Planar Wave Tank in Framework of OpenFOAM

2019 ◽  
Author(s):  
Zaibin Lin ◽  
Ling Qian ◽  
Wei Bai ◽  
Zhihua Ma ◽  
Hao Chen ◽  
...  
Keyword(s):  
Free Surface ◽  
Potential Flow ◽  
Wave Structure ◽  
Wave Model ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Fully Nonlinear ◽  
3 Dimensional ◽  
Nonlinear Potential ◽  
Numerical Wave

Abstract A 3-Dimensional numerical wave tank based on the fully nonlinear potential flow theory has been developed in OpenFOAM, where the Laplace equation of velocity potential is discretized by Finite Volume Method. The water surface is tracked by the semi-Eulerian-Lagrangian method, where water particles on the free surface are allowed to move vertically only. The incident wave is generated by specifying velocity profiles at inlet boundary with a ramp function at the beginning of simulation to prevent initial transient disturbance. Additionally, an artificial damping zone is located at the end of wave tank to sufficiently absorb the outgoing waves before reaching downstream boundary. A five-point smoothing technique is applied at the free surface to eliminate the saw-tooth instability. The proposed wave model is validated against theoretical results and experimental data. The developed solver could be coupled with multiphase Navier-Stokes solvers in OpenFOAM in the future to establish an integrated versatile numerical wave tank for studying efficiently wave structure interaction problems.

Experimental Optimization of Extreme Wave Sequences for the Deterministic Analysis of Wave/Structure Interaction

2006 ◽  
Vol 129 (1) ◽  
pp. 61-67 ◽  
Author(s):  
Günther F. Clauss ◽  
Christian E. Schmittner
Keyword(s):  
Large Scale ◽  
Wave Structure ◽  
Optimization Approach ◽  
Deterministic Analysis ◽  
Wave Groups ◽  
Wave Tank ◽  
Large Wave ◽  
Structure Interaction ◽  
Local Wave ◽  
Wave Structure Interaction

For the deterministic analysis of wave/structure interaction in the sense of cause-reaction chains, and for analyzing structure responses due to special wave sequences (e.g., three sisters phenomenon or other rogue wave groups) methods for the precise generation of tailored wave sequences are required. Applying conventional wave generation methods, the creation of wave trains satisfying given local wave parameters, and the generation of wave groups with predefined characteristics is often difficult or impossible, if sufficient accuracy is required. In this paper we present an optimization approach for the experimental generation of wave sequences with defined characteristics. The method is applied to generate scenarios with a single high wave superimposed to irregular seas. The optimization process is carried out in a small wave tank. The resulting control signal is then transferred to a large wave tank considering the electrical, hydraulic and hydrodynamical response amplitude operators (RAOs) of the respective wave generator in order to investigate wave/structure interaction at a large scale.

scholarly journals Investigation of Higher-Harmonic Wave Forces and Ringing Using CFD Simulations

2018 ◽  
Author(s):  
Arun Kamath ◽  
Hans Bihs ◽  
Csaba Pakozdi
Keyword(s):  
Structural Response ◽  
Vertical Cylinder ◽  
Wave Interaction ◽  
Wave Structure ◽  
Higher Order ◽  
Wave Forces ◽  
Numerical Wave Tank ◽  
Cfd Model ◽  
Structure Interaction ◽  
Wave Structure Interaction

Typical offshore structures are designed as tension-leg platforms or gravity based structures with cylindrical substructures. The interaction of waves with the vertical cylinders in high sea states can result in a resonant response called ringing. Here, the frequency of the structural response is close to the natural frequency of the structure itself and leads to large amplitude motions. This is a case of extreme wave loading in high sea states. This understanding of higher-order wave forces in extreme sea states is an essential parameter for obtaining a safe, reliable and economical design of an offshore structure. The study of such higher-order effects needs detailed near-field modelling of the wave-structure interaction and the associated flow phenomena. In such cases, a Computational Fluid Dynamics (CFD) model that can accurately represent the free surface and further the wave-structure interaction problem can provide important insights into the wave hydrodynamics and the structural response. In this paper, the open source CFD model REEF3D is used to simulate wave interaction with a vertical cylinder and the wave forces on the cylinder are calculated. The harmonic components of the wave force are analysed. The model employs higher-order discretisation schemes such as a fifth-order WENO scheme for convection discretisation and a third-order Runge-Kutta scheme for time advancement on a staggered Cartesian grid. The level set method is used to obtain the free surface, providing a sharp interface between air and water. The relaxation method is used to generate and absorb the waves at the two ends of the numerical wave tank. This method provides good quality wave generation and also the wave reflected from the cylinder are absorbed at the wave generation zone. In this way, the generated waves are not affected by the wave interaction process in the numerical wave tank. This is very essential in the studies of higher-order wave interaction problems which are very sensitive to the incident wave characteristics. The numerical results are compared to experimental results for higher-order forces on a vertical cylinder to validate the numerical model.

Experimental Optimization of Extreme Wave Sequences for the Deterministic Analysis of Wave/Structure Interaction

2005 ◽  
Author(s):  
Gu¨nther F. Clauss ◽  
Christian E. Schmittner
Keyword(s):  
Large Scale ◽  
Wave Structure ◽  
Optimization Approach ◽  
Deterministic Analysis ◽  
Wave Groups ◽  
Wave Tank ◽  
Large Wave ◽  
Structure Interaction ◽  
Local Wave ◽  
Wave Structure Interaction

For the deterministic analysis of wave/structure interaction in the sense of cause-reaction chains, and for analyzing structure responses due to special wave sequences (e.g. three sisters phenomenon or other rogue wave groups) methods for the precise generation of tailored wave sequences are required. Applying conventional wave generation methods, the creation of wave trains satisfying given local wave parameters and the generation of wave groups with predefined characteristics is often difficult or impossible, if sufficient accuracy is required. In this paper we present an optimization approach for the experimental generation of wave sequences with defined characteristics. The method is applied to generate scenarios with a single high wave superimposed to irregular seas. The optimization process is carried out in a small wave tank. The resulting control signal is then transferred to a large wave tank considering the electrical, hydraulic and hydrodynamical RAOs of the respective wave generator in order to investigate wave/structure interaction at a large scale.

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