4.1. API changes between versions

This page lists the main changes in the OpenFAST API (input files) between different versions.

The changes are tabulated according to the module input file, line number, and flag name. The line number corresponds to the resulting line number after all changes are implemented. Thus, be sure to implement each in order so that subsequent line numbers are correct.

4.1.1. OpenFAST v2.3.0 to OpenFAST dev

Added in OpenFAST dev
Module	Line	Flag Name	Example Value
HydroDyn	53	ExctnMod	0 ExctnMod - Wave Excitation model {0: None, 1: DFT, 2: state-space} (-)
OpenFAST	44	CalcSteady	true CalcSteady - Calculate a steady-state periodic operating point before linearization? [unused if Linearize=False] (flag)
OpenFAST	45	TrimCase	3 TrimCase - Controller parameter to be trimmed {1:yaw; 2:torque; 3:pitch} [used only if CalcSteady=True] (-)
OpenFAST	46	TrimTol	0.0001 TrimTol - Tolerance for the rotational speed convergence [used only if CalcSteady=True] (-)
OpenFAST	47	TrimGain	0.001 TrimGain - Proportional gain for the rotational speed error (>0) [used only if CalcSteady=True] (rad/(rad/s) for yaw or pitch; Nm/(rad/s) for torque)
OpenFAST	48	Twr_Kdmp	0 Twr_Kdmp - Damping factor for the tower [used only if CalcSteady=True] (N/(m/s))
OpenFAST	49	Bld_Kdmp	0 Bld_Kdmp - Damping factor for the blades [used only if CalcSteady=True] (N/(m/s))
InflowWind	48	InitPosition(x)	0.0 InitPosition(x) - Initial offset in +x direction (shift of wind box) [Only used with WindType = 5] (m)
AeroDyn	13	CompAA	False CompAA - Flag to compute AeroAcoustics calculation [only used when WakeMod=1 or 2]
AeroDyn	14	AA_InputFile	“unused” AA_InputFile - Aeroacoustics input file
AeroDyn	35	[separator line]	====== OLAF – cOnvecting LAgrangian Filaments (Free Vortex Wake) Theory Options ================== [used only when WakeMod=3]
AeroDyn	36	OLAFInputFileName	“Elliptic_OLAF.dat” OLAFInputFileName - Input file for OLAF [used only when WakeMod=3]
AirFoilTables	4*	BL_file	“unused” BL_file - The file name including the boundary layer characteristics of the profile. Ignored if the aeroacoustic module is not called.

*non-comment line count

Additional nodal output channels added for AeroDyn15, BeamDyn, and ElastoDyn.

4.1.2. OpenFAST v2.2.0 to OpenFAST v2.3.0

Removed in OpenFAST v2.3.0
Module	Line	Flag Name	Example Value
AeroDyn Airfoil Input File - Airfoil Tables	2	Ctrl	0 Ctrl ! Control setting (must be 0 for current AirfoilInfo)

Added in OpenFAST v2.3.0
Module	Line	Flag Name	Example Value
AeroDyn Airfoil Input File - Airfoil Tables	2	UserProp	0 UserProp ! User property (control) setting
AeroDyn	37	AFTabMod	1 AFTabMod - Interpolation method for multiple airfoil tables {1=1D interpolation on AoA (first table only); 2=2D interpolation on AoA and Re; 3=2D interpolation on AoA and UserProp} (-)

4.1.3. OpenFAST v2.1.0 to OpenFAST v2.2.0

No changes required.

4.1.4. OpenFAST v2.0.0 to OpenFAST v2.1.0

Added in OpenFAST v2.1.0
Module	Line	Flag Name	Example Value
BeamDyn driver	21	GlbRotBladeT0	True GlbRotBladeT0 - Reference orientation for BeamDyn calculations is aligned with initial blade root?

4.1.5. OpenFAST v1.0.0 to OpenFAST v2.0.0

Removed in OpenFAST v2.0.0
Module	Line	Flag Name	Example Value
BeamDyn	5	analysis_type	analysis_type - 1: Static analysis; 2: Dynamic analysis

Added in OpenFAST v2.0.0
Module	Line	Flag Name	Example Value
AeroDyn	22	SkewModFactor	“default” SkewModFactor - Constant used in Pitt/Peters skewed wake model {or “default” is 15/32*pi} (-) [used only when SkewMod=2; unused when WakeMod=0]
AeroDyn	30	Section header	====== Dynamic Blade-Element/Momentum Theory Options ============================================== [used only when WakeMod=2]
AeroDyn	31	DBEMT_Mod	2 DBEMT_Mod - Type of dynamic BEMT (DBEMT) model {1=constant tau1, 2=time-dependent tau1} (-) [used only when WakeMod=2]
AeroDyn	32	tau1_const	4 tau1_const - Time constant for DBEMT (s) [used only when WakeMod=2 and DBEMT_Mod=1]
BeamDyn	5	QuasiStaticInit	True QuasiStaticInit - Use quasi-static pre-conditioning with centripetal accelerations in initialization (flag) [dynamic solve only]
BeamDyn	11	load_retries	DEFAULT load_retries - Number of factored load retries before quitting the simulation
BeamDyn	14	tngt_stf_fd	DEFAULT tngt_stf_fd - Flag to use finite differenced tangent stiffness matrix (-)
BeamDyn	15	tngt_stf_comp	DEFAULT tngt_stf_comp - Flag to compare analytical finite differenced tangent stiffness matrix (-)
BeamDyn	16	tngt_stf_pert	DEFAULT tngt_stf_pert - perturbation size for finite differencing (-)
BeamDyn	17	tngt_stf_difftol	DEFAULT tngt_stf_difftol - Maximum allowable relative difference between analytical and fd tangent stiffness (-)
BeamDyn	18	RotStates	True RotStates - Orient states in the rotating frame during linearization? (flag) [used only when linearizing]

4.1.6. FAST v8.16 to OpenFAST v1.0.0

The transition from FAST v8 to OpenFAST is described in detail at FAST v8 and the transition to OpenFAST.

Removed in OpenFAST v1.0.0
Module	Line	Flag Name	Example Value
OpenFAST	18	CompSub	0 CompSub - Compute sub-structural dynamics (switch) {0=None; 1=SubDyn}

Added in OpenFAST v1.0.0
Module	Line	Flag Name	Example Value
OpenFAST	18	CompSub	0 CompSub - Compute sub-structural dynamics (switch) {0=None; 1=SubDyn; 2=External Platform MCKF}
AeroDyn	12	CavityCheck	False CavitCheck - Perform cavitation check? (flag)
AeroDyn	17	Patm	9999.9 Patm - Atmospheric pressure (Pa) [used only when CavitCheck=True]
AeroDyn	18	Pvap	9999.9 Pvap - Vapor pressure of fluid (Pa) [used only when CavitCheck=True]
AeroDyn	19	FluidDepth	9999.9 FluidDepth - Water depth above mid-hub height (m) [used only when CavitCheck=True]