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 v2.6.0 to OpenFAST dev

No changes.

4.1.2. OpenFAST v2.5.0 to OpenFAST v2.6.0

Many changes were applied to SubDyn input file format. You may consult the following example: (SubDyn's Input File): and the online SubDyn documentation.

Added in OpenFAST v2.6.0

Module

Line

Flag Name

Example Value

AeroDyn 15

TwrTi

0.0000000E+00 6.0000000E+00 1.0000000E+00 1.0000000E-01 [additional column in Tower Influence and Aerodynamics table]

SubDyn

8

GuyanLoadCorr.

False GuyanLoadCorection - Include extra moment from lever arm at interface and rotate FEM for floating

SubDyn

15

GuyanDampMod

0 GuyanDampMod - Guyan damping {0=none, 1=Rayleigh Damping, 2=user specified 6x6 matrix}

SubDyn

16

RayleighDamp

0.001, 0.003 RayleighDamp - Mass and stiffness proportional damping coefficients (Rayleigh Damping) [only if GuyanDampMod=1]

SubDyn

17

GuyanDampSize

6 GuyanDampSize - Guyan damping matrix size (square, 6x6) [only if GuyanDampMod=2]

SubDyn

18

GuyanDampMat

0.0000e+00 0.0000e+00 0.0000e+00 0.0000e+00 0.0000e+00 0.0000e+00

SubDyn

-23

GuyanDampMat

0.0000e+00 0.0000e+00 0.0000e+00 0.0000e+00 0.0000e+00 0.0000e+00

SubDyn

na

CablesSection

————————– CABLE PROPERTIES ————————————-

SubDyn

na

CablesSection

0 NCablePropSets - Number of cable cable properties

SubDyn

na

CablesSection

PropSetID EA MatDens T0

SubDyn

na

CablesSection

(-) (N) (kg/m) (N)

SubDyn

na

RigidSection

———————- RIGID LINK PROPERTIES ————————————

SubDyn

na

RigidSection

0 NRigidPropSets - Number of rigid link properties

SubDyn

na

RigidSection

PropSetID MatDens

SubDyn

na

RigidSection

(-) (kg/m)

HydroDyn

52

NBody

1 NBody - Number of WAMIT bodies to be used (-) [>=1; only used when PotMod=1. If NBodyMod=1, the WAMIT data contains a vector of size 6*NBody x 1 and matrices of size 6*NBody x 6*NBody; if NBodyMod>1, there are NBody sets of WAMIT data each with a vector of size 6 x 1 and matrices of size 6 x 6]

HydroDyn

53

NBodyMod

1 NBodyMod - Body coupling model {1: include coupling terms between each body and NBody in HydroDyn equals NBODY in WAMIT, 2: neglect coupling terms between each body and NBODY=1 with XBODY=0 in WAMIT, 3: Neglect coupling terms between each body and NBODY=1 with XBODY=/0 in WAMIT} (switch) [only used when PotMod=1]

Modified in OpenFAST v2.6.0

Module

Line

Flag Name

Example Value

AeroDyn 15

9

TwrShadow

0 TwrShadow - Calculate tower influence on wind based on downstream tower shadow (switch) {0=none, 1=Powles model, 2=Eames model}

SubDyn

26

Joints

JointID JointXss JointYss JointZss JointType JointDirX JointDirY JointDirZ JointStiff

SubDyn

27

Joints

(-) (m) (m) (m) (-) (-) (-) (-) (Nm/rad)

SubDyn

na

Members

MemberID MJointID1 MJointID2 MPropSetID1 MPropSetID2 MType COSMID

SubDyn

na

Members

(-) (-) (-) (-) (-) (-) (-)

SubDyn

na

ConcentratedM

CMJointID JMass JMXX JMYY JMZZ JMXY JMXZ JMYZ MCGX MCGY MCGZ

SubDyn

na

ConcentratedM

(-) (kg) (kg*m^2) (kg*m^2) (kg*m^2) (kg*m^2) (kg*m^2) (kg*m^2) (m) (m) (m)

HydroDyn

48

ExtnMod

1 ExctnMod - Wave-excitation model {0: no wave-excitation calculation, 1: DFT, 2: state-space} (switch) [only used when PotMod=1; STATE-SPACE REQUIRES *.ssexctn INPUT FILE]

HydroDyn

49

RdtnMod

2 RdtnMod - Radiation memory-effect model {0: no memory-effect calculation, 1: convolution, 2: state-space} (switch) [only used when PotMod=1; STATE-SPACE REQUIRES *.ss INPUT FILE]

HydroDyn

50

RdtnTMax

60 RdtnTMax - Analysis time for wave radiation kernel calculations (sec) [only used when PotMod=1 and RdtnMod>0; determines RdtnDOmega=Pi/RdtnTMax in the cosine transform; MAKE SURE THIS IS LONG ENOUGH FOR THE RADIATION IMPULSE RESPONSE FUNCTIONS TO DECAY TO NEAR-ZERO FOR THE GIVEN PLATFORM!]

HydroDyn

51

RdtnDT

0.0125 RdtnDT - Time step for wave radiation kernel calculations (sec) [only used when PotMod=1 and ExctnMod>0 or RdtnMod>0; DT<=RdtnDT<=0.1 recommended; determines RdtnOmegaMax=Pi/RdtnDT in the cosine transform]

HydroDyn

54

PotFile

“Barge” PotFile - Root name of potential-flow model data; WAMIT output files containing the linear, nondimensionalized, hydrostatic restoring matrix (.hst), frequency-dependent hydrodynamic added mass matrix and damping matrix (.1), and frequency- and direction-dependent wave excitation force vector per unit wave amplitude (.3) (quoted string) [1 to NBody if NBodyMod>1] [MAKE SURE THE FREQUENCIES INHERENT IN THESE WAMIT FILES SPAN THE PHYSICALLY-SIGNIFICANT RANGE OF FREQUENCIES FOR THE GIVEN PLATFORM; THEY MUST CONTAIN THE ZERO- AND INFINITE-FREQUENCY LIMITS!]

HydroDyn

55

WAMITULEN

1 WAMITULEN - Characteristic body length scale used to redimensionalize WAMIT output (meters) [1 to NBody if NBodyMod>1] [only used when PotMod=1]

HydroDyn

56

PtfmRefxt

0.0 PtfmRefxt - The xt offset of the body reference point(s) from (0,0,0) (meters) [1 to NBody] [only used when PotMod=1]

HydroDyn

57

PtfmRefyt

0.0 PtfmRefyt - The yt offset of the body reference point(s) from (0,0,0) (meters) [1 to NBody] [only used when PotMod=1]

HydroDyn

58

PtfmRefzt

0.0 PtfmRefzt - The zt offset of the body reference point(s) from (0,0,0) (meters) [1 to NBody] [only used when PotMod=1. If NBodyMod=2,PtfmRefzt=0.0]

HydroDyn

59

PtfmRefztRot

0.0 PtfmRefztRot - The rotation about zt of the body reference frame(s) from xt/yt (degrees) [1 to NBody] [only used when PotMod=1]

HydroDyn

60

PtfmVol0

6000 PtfmVol0 - Displaced volume of water when the body is in its undisplaced position (m^3) [1 to NBody] [only used when PotMod=1; USE THE SAME VALUE COMPUTED BY WAMIT AS OUTPUT IN THE .OUT FILE!]

HydroDyn

61

PtfmCOBxt

0.0 PtfmCOBxt - The xt offset of the center of buoyancy (COB) from (0,0) (meters) [1 to NBody] [only used when PotMod=1]

HydroDyn

62

PtfmCOByt

0.0 PtfmCOByt - The yt offset of the center of buoyancy (COB) from (0,0) (meters) [1 to NBody] [only used when PotMod=1]

HydroDyn

69-74

AddF0

0 AddF0 - Additional preload (N, N-m) [If NBodyMod=1, one size 6*NBody x 1 vector; if NBodyMod>1, NBody size 6 x 1 vectors]

HydroDyn

75-80

AddCLin

0 0 0 0 0 0 AddCLin - Additional linear stiffness (N/m, N/rad, N-m/m, N-m/rad) [If NBodyMod=1, one size 6*NBody x 6*NBody matrix; if NBodyMod>1, NBody size 6 x 6 matrices]

HydroDyn

81-86

AddBLin

0 0 0 0 0 0 AddBLin - Additional linear damping(N/(m/s), N/(rad/s), N-m/(m/s), N-m/(rad/s)) [If NBodyMod=1, one size 6*NBody x 6*NBody matrix; if NBodyMod>1, NBody size 6 x 6 matrices]

HydroDyn

87-92

AddBQuad

0 0 0 0 0 0 AddBQuad - Additional quadratic drag(N/(m/s)^2, N/(rad/s)^2, N-m(m/s)^2, N-m/(rad/s)^2) [If NBodyMod=1, one size 6*NBody x 6*NBody matrix; if NBodyMod>1, NBody size 6 x 6 matrices]

HydroDyn

na

Simple Coef Tab

SimplCd SimplCdMG SimplCa SimplCaMG SimplCp SimplCpMG SimplAxCa SimplAxCaMG SimplAxCa SimplAxCaMG SimplAxCp SimplAxCpMG

HydroDyn

na

(-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-)

HydroDyn

na

Depth Coef Tab

Dpth DpthCd DpthCdMG DpthCa DpthCaMG DpthCp DpthCpMG DpthAxCa DpthAxCaMG DpthAxCa DpthAxCaMG DpthAxCp DpthAxCpMG

HydroDyn

na

  1. (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-)

HydroDyn

na

Member Coef Tab

MemberID MemberCd1 MemberCd2 MemberCdMG1 MemberCdMG2 MemberCa1 MemberCa2 MemberCaMG1 MemberCaMG2 MemberCp1 MemberCp2 MemberCpMG1 MemberCpMG2 MemberAxCd1 MemberAxCd2 MemberAxCdMG1 MemberAxCdMG2 MemberAxCa1 MemberAxCa2 MemberAxCaMG1 MemberAxCaMG2 MemberAxCp1 MemberAxCp2 MemberAxCpMG1 MemberAxCpMG2

HydroDyn

na

(-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-) (-)

HydroDyn

na

OutList names

see OutlistParameters.xlsx for new and revised output channel names

Removed in OpenFAST v2.6.0

Module

Line

Flag Name

Example Value

HydroDyn

68

na

———————- FLOATING PLATFORM FORCE FLAGS ————————– [unused with WaveMod=6]

HydroDyn

69

PtfmSgF

True PtfmSgF - Platform horizontal surge translation force (flag) or DEFAULT

HydroDyn

70

PtfmSwF

True PtfmSwF - Platform horizontal sway translation force (flag) or DEFAULT

HydroDyn

71

PtfmHvF

True PtfmHvF - Platform vertical heave translation force (flag) or DEFAULT

HydroDyn

72

PtfmRF

True PtfmRF - Platform roll tilt rotation force (flag) or DEFAULT

HydroDyn

73

PtfmPF

True PtfmPF - Platform pitch tilt rotation force (flag) or DEFAULT

HydroDyn

74

PtfmYF

True PtfmYF - Platform yaw rotation force (flag) or DEFAULT

4.1.3. OpenFAST v2.4.0 to OpenFAST v2.5.0

Added in OpenFAST v2.5.0

Module

Line

Flag Name

Example Value

IfW driver

6

[separator line]

===================== File Conversion Options =================================

IfW driver

7

WrHAWC

false WrHAWC - Convert all data to HAWC2 format? (flag)

IfW driver

8

WrBladed

false WrBladed - Convert all data to Bladed format? (flag)

IfW driver

9

WrVTK

false WrVTK - Convert all data to VTK format? (flag)

InflowWind

7

VFlowAng

0 VFlowAng - Upflow angle (degrees) (not used for native Bladed format WindType=7)

4.1.4. OpenFAST v2.3.0 to OpenFAST v2.4.0

Added in OpenFAST v2.4.0

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.

4.1.5. Modified in OpenFAST v2.4.0

Module

Line

Flag Name

Example Value

AirFoilTables

40*

filtCutOff

“DEFAULT” filtCutOff - Reduced frequency cut-off for low-pass filtering the AoA input to UA, as well as the 1st and 2nd derivatives (-) [default = 0.5]

*non-comment line count, excluding lines contained if NumCoords is not 0.

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

4.1.6. 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} (-)

4.1.7. OpenFAST v2.1.0 to OpenFAST v2.2.0

No changes required.

4.1.8. 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?

4.1.9. 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]

4.1.10. 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]