Maximum Number of DOFs in OpenFAST

Dear Jason,

What is the maximum number of degrees of freedom that can be used in OpenFAST for a 3-blade turbine? I know the number is 24 for FAST v7, but I’m not sure about FAST v8 and OpenFAST.

Many thanks,
Yanchang

Dear Yanchang,

The maximum number of DOFs in the ElastoDyn module of FAST v8 / OpenFAST, which was derived from the structural model of FAST v7, is still 24. However, in FAST v8 and OpenFAST, structural DOFs are also available in other structural dynamic modules, like BeamDyn for modeling the blades, SubDyn for modeling the substructure, and Structural Control (StC, formerly TMD) for modeling tuned-mass dampers (TMDs) and tuned liquid-column dampers (TLCDs). With these additional structural dynamic modules, the number of DOFs available in FAST v8 and OpenFAST are dynamically allocatable, so, the total number of structural DOFs is not limited.

Best regards,