Question about different initial platform positions in ElastoDyn input files

[wufangyun92]

Hello,

I noticed that in the attached image, the initial platform positions (PtfmSurge, PtfmSway, PtfmHeave, PtfmRoll, PtfmPitch, and PtfmYaw) are different between the two ElastoDyn input files (IEA-15-240-RWT-UMaineSemi_ElastoDynT1.dat and ...T2.dat).

Why the initial positions of the floating platforms are different?
Also, if I want to add more turbines to my FAST.Farm simulation, how should I adjust these initial platform position values accordingly?

Thank you!

Best regards,

[Yuksel-Rudy]

The initial positions in the MD_shared FAST.Farm example were changed based on the expected mean offset from a quasi-static analysis. Except for platform yaw. The platforms are at 180 deg opposing orientations so that there are two columns facing towards each other due to the shared line. And the nacelle yaw on the rotated platform is also adjusted so that both turbines face upwind.

These initial positions are optional (for X, Y, Z, RX, RY but not for yaw). You can have them as zero but you will experience initial transient in the fast.farm simulation in the beginning of the simulation.

If you want to add more turbines to your FAST.Farm simulation, you could run quasi-static simulation to figure our initial platform position if you want to populate initial platform positions based of the same environmental conditions (e.g., running RAFT or MoorPy beforehand).