Nonlinear hydrodynamics of freely floating symmetric bodies in waves by three-dimensional fully nonlinear potential-flow numerical wave tank

2021 ◽  
Vol 113 ◽  
pp. 102727
Author(s):  
Sung-Jae Kim ◽  
Moo-Hyun Kim ◽  
Weoncheol Koo
Keyword(s):  
Potential Flow ◽  
Three Dimensional ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Fully Nonlinear ◽  
Nonlinear Potential ◽  
Nonlinear Hydrodynamics ◽  
Numerical Wave

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.

scholarly journals Investigation of Focusing Wave Properties in a Numerical Wave Tank with a Fully Nonlinear Potential Flow Model

2019 ◽  
Vol 7 (10) ◽  
pp. 375 ◽  
Author(s):  
Weizhi Wang ◽  
Arun Kamath ◽  
Csaba Pakozdi ◽  
Hans Bihs
Keyword(s):  
Wave Height ◽  
Potential Flow ◽  
Wave Steepness ◽  
Numerical Wave Tank ◽  
Wave Groups ◽  
Wave Tank ◽  
Fully Nonlinear ◽  
Nonlinear Potential ◽  
Numerical Wave ◽  
Focused Wave

Nonlinear wave interactions and superpositions among the different wave components and wave groups in a random sea sometimes produce rogue waves with extremely large wave heights that appear unexpectedly. A good understanding of the generation and evolution of such extreme wave events is of great importance for the analysis of wave forces on marine structures. A fully nonlinear potential flow (FNPF) model is proposed in the presented paper to investigate the different factors that influence the wave focusing location, focusing time and focusing wave height in a numerical wave tank. Those factors include wave steepness, spectrum bandwidth, wave generation method, focused wave spectrum, and wave spreading functions. The proposed model solves the Laplace equation together with the boundary conditions on a σ -coordinate grid using high-order discretisation schemes on a fully parallel computational framework. The model is validated against the focused wave experiments and thereafter used to obtain insights into the effects of the different factors. It is found that the wave steepness contributes to changing the location and time of focus significantly. Spectrum bandwidth and directional spreading affect the focusing wave height and profile, for example, a wider bandwidth and a wider directional spread lead to a lower focusing wave height. A Neumann boundary condition represents the nonlinearity of the wave groups better than a relaxation method for wave generation.

scholarly journals Development of a Three-Dimensional Fully Nonlinear Potential Numerical Wave Tank for a Heaving Buoy Wave Energy Converter

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Sung-Jae Kim ◽  
Weoncheol Koo
Keyword(s):  
Wave Energy ◽  
Large Amplitude ◽  
Three Dimensional ◽  
Wave Energy Converter ◽  
Numerical Wave Tank ◽  
Energy Converter ◽  
Wave Tank ◽  
Fully Nonlinear ◽  
Nonlinear Potential ◽  
Numerical Wave

The hydrodynamic performance of a vertical cylindrical heaving buoy-type floating wave energy converter under large-amplitude wave conditions was calculated. For this study, a three-dimensional fully nonlinear potential-flow numerical wave tank (3D-FN-PNWT) was developed. The 3D-FN-PNWT was based on the boundary element method with Rankine panels. Using the mixed Eulerian–Lagrangian (MEL) method for water particle movement, nonlinear waves were produced in the PNWT. The PNWT can calculate the wave forces acting on the buoy accurately using an acceleration potential approach. The constant panels and least-square gradient reconstruction method were applied to regridding of computational boundaries. An artificial damping zone was employed to satisfy the open-sea conditions at the end free surface boundaries. The diffraction and radiation problems were solved, and their solutions were confirmed by a comparison with previous studies. The interaction of the incident wave, floating body, and power take-off (PTO) behavior was examined in the time domain using the developed 3D-FN-PNWT. From comparison, the difference between the conventional linear analysis and the nonlinear analysis in large-amplitude waves was examined.

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.

Free and Forced Sloshing Motions in a 2-D Numerical Wave Tank

2002 ◽  
Author(s):  
Janette B. Frandsen ◽  
Alistair G. L. Borthwick
Keyword(s):  
Potential Flow ◽  
Numerical Solutions ◽  
Breaking Waves ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Flow Equations ◽  
Time Stepping ◽  
Nonlinear Potential ◽  
Numerical Wave ◽  
Difference Time

This article describes a 2D numerical wave tank that utilises stretched mappings in order to resolve accurately the moving free surface of a liquid. It is assumed that the flow is incompressible and inviscid. Numerical solutions of the governing nonlinear potential flow equations are obtained using a finite-difference time-stepping scheme on σ-transformed grids. Free and forced sloshing motions are simulated in a rectangular tank, and the results compare well with analytical and other numerical methods. It is concluded that the present potential flow model provides a simple way of simulating steep non-breaking waves, that may be readily extended to the prediction of 3D wave motions.

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