Dear Taha,
A few comments:
- It should be easy to separate “B” from a FAST v8 linearization process into separate input (B) and disturbance input (Bd) matrices by simply partitioning the “B” matrix output.
- In your attachment you seem to want to separate the wind disturbance separately for each blade. I’m not sure why you’d want to do this and I don’t agree with your solution, as the wind disturbance that is part of the FAST v8 linearization process provides a uniform disturbance across the complete rotor disk (when the vertical shear is nonzero).
- We typically recommend linearizing the FAST model at a sufficient number of azimuth steps around the rotor revolution. This is discussed in the following forum topic: Campbell diagram for 5MW turbine rotor (especially my posts dated Sep 22, 2016 and Dec 12, 2016).
- It is easy to specify wind input to FAST v8 with ramps or step changes by using “uniform wind” files. See the documentation supplied with the InflowWind module for instructions: wind.nrel.gov/nwtc/docs/InflowWind_Manual.pdf. In older versions of FAST, the “uniform wind” files were called “hub-height” wind files and were entered in the AeroDyn input file instead of an InflowWind input file.
I hope that helps.
Best regards,