Aerodyn v FAST wind direction convention

A simple question, and one that I should know the answer to, but I am confused by results I am getting:

The manuals say the AeroDyn wind direction convention is opposite the FAST convention. So if I input +5 deg wind direction in a HH wind file in AeroDyn, shouldn’t I get -5 deg wind direction output from FAST (HorWndDir)? But I’m not and that has me confused.

David

Dear David,

Yes, I agree that AeroDyn and FAST v7 have opposite wind-direction conventions. See the following forum topic for more information: http://forums.nrel.gov/t/is-positive-yaw-error-clockwise/582/1. I’d be surprised if you didn’t see an opposite sign in the wind direction between FAST and AeroDyn.

Best regards,