Add harmonic force at tower top

Dear Jason,

I’m wondering how to add a customised harmonic excitation (with defined frequencies) on the tower top by changing the source code. Thanks!

Best regards,
Stein

Dear Stein,

Adding your own point force at the tower top will require a minor change to the source code. What I would do, is add your force to the force input to ElastoDyn from the nacelle tuned-mass damper (NTMD) output from ServoDyn. That is, in SUBROUTINE FAST_Solver.f90/ED_InputSolve(), the ServoDyn output y_SrvD%NTMD%Mesh is transferred to u_ED%NacelleLoads using a point-to-point mesh-mapping for loads. You can add your load to u_ED%NacelleLoads after this call i.e.

u_ED%NacelleLoads%Force(1) = u_ED%NacelleLoads(1) + the force you want in X u_ED%NacelleLoads%Force(2) = u_ED%NacelleLoads(2) + the force you want in Y u_ED%NacelleLoads%Force(3) = u_ED%NacelleLoads(3) + the force you want in Z

The Force(:slight_smile: field of the NacelleLoads mesh is in the global inertial-frame coordinate system.

Best regards,

Thanks for your quick reply…I’ll try to modify the code.

Best wishes,
Stein