Hello,
I am writing regarding a problem I have had using setting EdgeDOF to true. Up to now I had only performed rigid blade calculations.
When I try to set EdgeDOF to true, together with FlapDOF1 and FlapDOF2, I get a lot of warnings at the beginning of the simulations, and then NaN values in the results. The other two DOFs for the blades, FlapDOF1 and FlapDOF2, are not too problematic for me, although I have to use very high values for the associated “structural damping in percent of critical”, BldFlDmp(1) and BldFlDmp(2), basically 100%, to get results different than NaN (and for it to work, EdgeDOF has to be set to FALSE). I have tried to change many parameters in the blade structural file, but that has not been of any help.
Has anybody experienced such a problem before?
Thanks in advance,
Simon
Dear Simon,
Sounds like a numerical problem due to the use of a time step that is too large to maintain numerical stability of the solution. See the following FAQ for guidance on selecting a time step for FAST v7: wind.nrel.gov/designcodes/FAQ.html#FASTTimeStep.
Best regards,
Dear Jason,
It seems indeed that this was the problem I had.
Thank you very much!
Simon