scholarly journals Identification of Wave Energy Device Models From Numerical Wave Tank Data—Part 1: Numerical Wave Tank Identification Tests

2016 ◽  
Vol 7 (3) ◽  
pp. 1012-1019 ◽  
Author(s):  
Josh Davidson ◽  
Simone Giorgi ◽  
John V. Ringwood
2020 ◽  
Vol 146 ◽  
pp. 2499-2516 ◽  
Author(s):  
Christian Windt ◽  
Josh Davidson ◽  
Edward J. Ransley ◽  
Deborah Greaves ◽  
Morten Jakobsen ◽  
...  

Author(s):  
Sung-Jae Kim ◽  
Weoncheol Koo ◽  
Moo-Hyun Kim

Abstract The aim of this paper is to evaluate the hydrodynamic performance of a heaving buoy type wave energy converter (WEC) and power take-off (PTO) system. To simulate the nonlinear behavior of the WEC with PTO system, a three-dimensional potential numerical wave tank (PNWT) was developed. The PNWT is a numerical analysis tool that can accurately reproduce experiments in physical wave tanks. The developed time-domain PNWT utilized the previously developed NWT technique and newly adopted the side wall damping area. The PNWT is based on boundary element method with constant panels. The mixed Eulerian-Lagrangian method (MEL) and acceleration potential approach were adopted to simulate the nonlinear behaviors of free-surface nodes associated with body motions. The PM spectrum as an irregular incident wave condition was applied to the input boundary. A floating or fixed type WEC structure was placed in the center of the computational domain. A hydraulic PTO system composed of a hydraulic cylinder, hydraulic motor and generator was modeled with approximate Coulomb damping force and applied to the WEC system. Using the integrated numerical model of the WEC with PTO system, nonlinear interaction of irregular waves, the WEC structure, and the PTO system were simulated in the time domain. The optimal hydraulic pressure of the PTO condition was predicted. The hydrodynamic performance of the WEC was evaluated by comparing the linear and nonlinear analytical results and highlighted the importance accounting for nonlinear free surfaces.


2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Sung-Jae Kim ◽  
Weoncheol Koo

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.


Author(s):  
Shangyan Zou ◽  
Ossama Abdelkhalik

Abstract This paper presents a high-fidelity numerical wave tank simulation for Variable Geometry Wave Energy Converters (VG-WECs). Typically, wave energy converters require reactive power to optimize the energy conversion, which significantly jeopardizes the economic index of the system. The proposed VGWECs allows comprehensive shape-changing not only in response to ocean climate but also to reduce the reactive power requirements on the power take-off (PTO) unit. This design aims at eliminating reactive power with minimal impact on optimality in terms of energy production. To investigate the dynamic behavior of the VGWEC, this model is simulated in a Computational Fluid Dynamics (CFD) based Numerical Wave Tank (CNWT) using ANSYS 2-way Fluid Structure Interaction (FSI) tool. The interaction between irregular waves and the VGWEC is simulated. The numerical results show that the proposed VGWEC has large deformation and motion in response to the incoming wave. This highly nonlinear interaction between waves and VGWEC can be leveraged to eliminate reactive power.


IEEE Access ◽  
2018 ◽  
Vol 6 ◽  
pp. 6585-6593 ◽  
Author(s):  
Xiaojie Tian ◽  
Qingyang Wang ◽  
Guijie Liu ◽  
Wei Deng ◽  
Zhiming Gao

Author(s):  
Hans Bihs ◽  
Mayilvahanan Alagan Chella ◽  
Arun Kamath ◽  
Øivind Asgeir Arntsen

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.


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