Strange oscillation response of openFAST simulation in 'Steady-state' stage

Wind & Water Computer-Aided Engineering Software Tools
1

Dear Jason,

I run the simulation with some results that presented strange oscillation in steady-state. An example is attached below.

We can see that after the 50s, the response reaches a ‘steady-state’, but the oscillation is strange. It should be a harmonic oscillation but seems some step-like output. The module timestep is 0.0025 and there are multiple points on a single plateau in these plots. Do you have any suggestions on how to fix this problem? Thank you!

Ct time history
1.jpg

Local view of the Ct time history
2.jpg

2

Dear Xianping,

The problem you are seeing is related to the precision of your OpenFAST output. A similar question was asked and answered in the following forum topic: Positive vs Negative yaw Error Effect - #3 by Jason.Jonkman.

Best regards,

3

Dear Jason,

That works. Thank you for your help.