Thesis: CFD Simulation of Floating Turbines
 

Dear OpenFOAM community,

Last week I presented my MSc thesis entitled 'CFD Simulation of a Floating Wind Turbine with OpenFOAM: an FSI approach based on the actuator line and relaxation zone methods', for which I graduated in Aerospace Engineering at TU Delft.
I worked on the implementation, in OpenFOAM, of a framework for the CFD simulation of floating wind turbines under wind and wave loads.
By using the actuator line method, the computational cost has been reduced up to 3 orders of magnitude compared to blade-resolved simulations.

Attachment 92718

The tool is built upon two existing libraries: turbinesFoam (by P. Bachant, for rotor modeling based on the actuator line method and waves2Foam (by Niels Jacobsen, for wave-field generation and absorption based on the relaxation zone method).
The multi-phase simulation uses the interFoam solver in combination with a morphing mesh technique and rigid-body model to represent the platform.

The mooring restraints are computed with a quasi-steady, catenary model from waves2Foam.
The turbinesFoam library, targeted at bottom fixed turbines, is modified so that it can accommodate arbitrary motions along the rigid-body DoFs.
Although only pure harmonic motions are available, the user can easily modify the library to include any desired function.
Lastly, the ALM and rigid body libraries were coupled so that the user can also impose the floater’s motion onto the turbine.

The libraries and all cases run throughout the thesis can be accessed on GitHub.
This work should be seen as a proof of concept only: two master students will be focusing their thesis on its careful validation and optimization.
The report is structured in such a way that it can be followed by anyone interested in CFD and floating turbines, no matter their previous experience with the topic.
I wanted to keep everything as transparent, accessible, and replicable as possible.

At the beginning of the project, I was a newcomer to the world of OpenFOAM.
This work has helped me deepen my knowledge of this powerful tool.
Recall however that, as my first contact with OpenFOAM, it is far from perfect and you might as well find errors in the implementation.
However, I would be more than happy if it can help the community gain some insight into floating turbines.

Last, I want to thank you all for building such a nice community.
Building this tool wouldn’t have been possible without the documentation you have made available, and all the questions answered through this forum.

Thank you all, let’s keep up the good work!