The Wave Energy Converter Software Simulator (WEC-Sim) is an open-source software consisting of Simulink library blocks and MATLAB scripts that facilitate rapid model construction, simulation, and analysis of a wide range of offshore devices. A collaborative effort since 2014 between the National Renewable Energy Laboratory and Sandia National Laboratories, the WEC-Sim v5.0 release represents a substantial update that widely enhances the capabilities and overhauls the code structure in addition to updated documentation, bug-fixes, and clean-up.
Since the release of WEC-Sim v1.0 in December 2014, WEC-Sim has become a popular tool for WEC numerical modeling for many different device types—and even for some non-wave energy applications. Furthermore, a literature review found over 125 publications featuring WEC-Sim between 2013 and 2022. Early WEC-Sim publications were led by the code developers NREL and SNL, but in recent years there has been strong growth in external conference and journal articles. WEC-Sim’s impact on the wave energy community was recently highlighted with an R&D 100 award.
The following sections describe the v5.0 updates in greater detail:
Most significantly, code refactoring was performed to simplify and homogenize function/variable naming conventions, remove duplicate methods, and streamline future development and troubleshooting by simplifying execution pathways. As a result of this significant revision, affecting nearly all supporting libraries and scripts, many models developed in V5.0 will not be backwards compatible with older WEC-Sim versions. Detailed documentation and an automatic code update utility are available on the WEC-Sim GitHub.
Many WECs rely on a flexible tether or cable (i.e., a coupler that can only transmit a tensile force) connecting two hydrodynamically active bodies. This is a distinct implementation from the body-to-seabed mooring problem already supported. A basic cable library, documentation, and examples have been added to facilitate modeling this type of device. This implementation is sufficient to resolve the resultant cable-exerted forces on and associated dynamics of the coupled bodies but does not resolve the motions of the cable itself.
Simulation and control of a WEC Power-Take-Off (PTO) has been enhanced with a substantially expanded PTO-Sim library. This emulates commonly used functions of some other Simscape libraries, like Electrical, Hydraulics, and Driveline, but does not require them. Utilizing PTO-Sim blocks in a WEC-Sim model has been streamlined. Controllers can be specified using the user-defined actuation blocks to interface these PTO-Sim blocks with a WEC-Sim model.
As meshing and Boundary Element Method (BEM) tools continue to expand, v5.0 includes new AQWA examples, accepts binary STL files, and improves tools to work with Capytaine outputs. Additionally, free-surface visualization is now available within the Simscape Explorer window: it is no longer necessary to export results to Paraview to generate a free surface visualization.
This work is supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) through the Water Power Technologies Office (WPTO).