FAST v7 differential equations and Integration scheme

Dear Sir,

I need proper references with the differential equations solved in FAST v7 along with the details of the integration scheme used.
Additionally, it would help if I could get some information on how and which damping modes are taken in the time domain analysis while the turbine is operational.

Thanks
Subham

Dear @Kashyap.Subham,

The structural equations of motion of FAST v7 are the same as those of the ElastoDyn module of OpenFAST, documented here: 4.2.7. ElastoDyn Users Guide and Theory Manual — OpenFAST v3.2.0 documentation. In FAST v7, the states are updated from one time step to the next based on a fourth-order Adams-Bashforth-Adams-Moulton (ABM4) predictor-corrector integration scheme. This integrator is initialized using a fourth-order Runge-Kutta (RK4) integration scheme.

For an aeroelastic simulation, damping results from structural damping and aerodynamic/aeroelastic damping. Technically, any velocity-dependent force acts like a damping, so, you could also say forces such as gyroscopic, Coriolis, and generator torque-speed curves are also “damping like” terms.

Best regards,

Dear Jason,

I appreciate your input. I would further like to take a step ahead and quantify the aerodynamic damping of an operating wind turbine during a seismic event. How can I use FAST Seismic Module in doing so?

Thanks
Subham

Dear @Kashyap.Subham,

Perhaps you could compute the structural response with and without the aerodynamic loads applied and calculate the effect of aerodynamic damping by comparing these responses?

Best regards,