Sowfa - Turbine in Yaw


I looked at the SOWFA code and saw that the yaw angle of the turbine(s) is also defined in the coupling component (not just FAST).
Why do all forces and positions from FAST to openFOAM and velocities from openFOAM to FAST are additionally transformed?

void horizontalAxisWindTurbinesFAST::getBldPosForce(int iturb)

At the moment I do not understand why this is done.
Is it not enough to yaw the turbine in FAST?
I thought that all the transformation for the yaw cases are done within FAST aren’t they?
What is the advantage of the additional yaw angle?

Kind regards