Version 1.2 of WEC-Sim is now available on GitHub, and there are lots of great updates!
The NREL/SNL team is also implementing a multi-branch approach, allowing users to use the stable ‘master’ branch or the more advanced/under development ‘dev’ branch.
Updates in ‘master’
- Nonlinear Froude-Krylov hydrodynamics and hydrostatics
- State space radiation
- Wave directionality
- User-defined wave elevation time-series
- Imports non-dimensionalized BEMIO hydrodynamic data (instead of fully dimensional coefficients)
- ‘Variant Subsystems’ implemented to improve code stability (instead of if statements)
- Bug fixes
Updates in ‘dev’:
- Morison Elements
- Body2Body Interactions
WEC-Sim (Wave Energy Converter SIMulator) is an open source wave energy converter simulation tool being developed as a joint effort between the National Renewable Energy Laboratory (NREL) and Sandia National Laboratories (SNL) with funding from the U.S. Department of Energy’s Wind and Water Power Technologies Office. The code is developed in MATLAB/SIMULINK using the multi-body dynamics solver SimMechanics. WEC-Sim has the ability to model devices that are comprised of rigid bodies, power-take-off systems, and mooring systems. Simulations are performed in the time-domain by solving the governing WEC equations of motion in 6 degrees-of-freedom as described in the WEC-Sim Theory Manual.
The NREL/SNL team would like to receive feedback on how WEC-Sim can be improved in the future and to facilitate this process a questionnaire has been created. It is highly encouraged of all users to fill out the questionnaire as soon as possible. Thank you for your time and please direct any questions about the current release to Nathan Tom, Nathan.firstname.lastname@example.org.
Offshore renewable energy should be fun too! Researchers in Oregon, USA have developed a simple working model of a wave energy converter (a direct drive linear generator) that you can make at home with your kids! Actually, it looks like the kids can make it by themselves:
The device was designed as part of a teaching curriculum. For more, including paper instructions and how to make the project into a full-fledged science experiment, see the article by NNMREC:
The Structural Design of Wave Energy Devices (SDWED) project, led by Aalborg University, has had an amazing output of free software including advanced hydrodynamic models, wave to wire models, and a spectral fatigue model:
Also, at the bottom of that page is a list many other free software products.
“The Structural Design of Wave Energy Devices project (SDWED) 2010-2014 is an international research alliance supported by the Danish Council for Strategic Research. The project is a five-year endeavour to harness the energy potential in wave energy at competitive costs.” (www.sdwed.civil.aau.dk/)
MoorDyn is a lumped-mass mooring line model designed for easy coupling with other software (i.e. floating platform models). It supports arbitrary line interconnections, clump weights and floats, and different line properties. The model accounts for internal axial stiffness and damping forces, weight and buoyancy forces, hydrodynamic forces from Morison’s equation, and vertical spring-damper forces from contact with the seabed.
The original version is written in C++ and has been successfully coupled with FAST v7 and other tools/models in Matlab and Simulink. A separate Fortran-based version has recently been incorporated into FAST v8 (nwtc.nrel.gov/FAST8). More information and downloads can be found at www.matt-hall.ca/software/moordyn.
Wave energy converters (WECs) will be deployed in groups or “wave farms”. The hydrodynamic interactions between WECs in a wave farm (i.e. how waves that are absorbed, scattered, or radiated by one WEC affect the others) will have siginificant impacts on the overall power performance of the wave farm.
A recently published paper by researchers at The University of Edinburgh titled “A novel method for deriving the diffraction transfer matrix and its application to multi-body interactions in water waves” presents a new method for computing wave farm performance with results from commercial software. Using the theory, WEC array interactions can be computed on the order of 1,000-10,000 times faster than with standard methods. However, the method presented in the paper is still somewhat complicated to implement, which would make it difficult for others to employ it.
Open source to the rescue! The authors have chosen to share the wave farm code used in the paper for free. The Matlab package that they developed, including examples of WEC array performance, can be found on GitHub:
The authors chose to release the code to increase the impact of the work. The code is already being used by another researcher at Oregon State University as part of his wave farm design optimization work and is being evaluated for use by the International DTOcean project, which “aims at accelerating the industrial development of ocean energy power generation knowledge, and providing design tools for deploying the first generation of wave and tidal energy converter arrays.”