Environment Specification

1. 1 input line.

ENVIronment DATA SPECification

2. Text for describing all environmental conditions, 3 input lines.

TXENV

  • TXENV: character(60): Environmental conditions description

One or more instances of data groups Regular waves, Irregular waves, Wind and Current can be included after this data group.

3. Regular waves

1 identifying input line

REGUlar WAVE SPECification

1 input line

CHREWA

  • CHREWA: character(8): Regular wave condition identifier

1 input line

NREGWA

  • NREGWA: integer: Number of regular waves

NREGWA input lines

WAVAMP WAVPER PHASE DIR

  • WAVAMP: real: Wave amplitude, \(\mathrm {[L]}\)

  • WAVPER: real: Wave period, \(\mathrm {[T]}\)

  • PHASE: real: Phase angle according to the Theory Manual, \(\mathrm {[deg]}\)

  • DIR: real: Wave propagation direction, \(\mathrm {[deg]}\)

4. Irregular waves

When unidirectional waves are used (IWADR1 = 0), the wave elevation may be read from an ASCII file. See Reading wave elevation from file.

1 identifying input line

IRREgular WAVE SPECification

1 input line

CHIRWA

  • CHIRWA: character(8): Irregular wave condition identifier

1 input line

IWASP1    IWADR1   IWASP2    IWADR2

  • IWASP1: integer: Wave spectrum type code, wind sea

    • = 11: Pierson-Moskowitz spectrum with 1 parameter

    • = 12: Pierson-Moskowitz spectrum with 2 parameters (average wave period) - ISSC

    • = 13: Pierson-Moskowitz spectrum with 2 parameters (zero crossing wave period)

    • = 21: JONSWAP spectrum with 6 parameters

    • = 22: JONSWAP spectrum with 2 parameters

    • = 23: JONSWAP spectrum with 3 parameters

    • = 24: Double peaked spectrum (Torsethaugen)

    • = 31: Ochi-Hubble spectrum with 1 parameter

    • =100: Numerically defined spectrum

  • IWADR1: integer: Wave spreading code, wind sea, dummy if IWASP1=100

    • = 0: unidirectional

    • = 1: cos spreading function

  • IWASP2: integer: Wave spectrum type code, swell

    • = 0: no swell spectrum

    • > 0: As for IWASP1

  • IWADR2: integer: Wave spreading code, swell, dummy if IWASP2=0

    • = 0: unidirectional

    • = 1: cos spreading function

If IWASP1=100, IWASP2 must be 0

1 identifying input line

WAVE SPECtrum WIND

For IWA5P1=11, Pierson-Moskowitz spectrum with 1 parameter

SIWAHE

  • SIWAHE: real: Significant wave height, \(\mathrm {[L]}\)

For IWASP1=12, Pierson-Moskowitz spectrum with 2 parameters

SIWAHE AVWAPE

  • SIWAHE: real: Significant wave height, \(\mathrm {[L]}\)

  • AVWAPE: real: Average wave period, \(\mathrm {[T]}\)

For IWASP1=13, Pierson-Moskowitz sectrum with 2 parameters

SIWAHE ZCWAPE

  • SIWAHE: real: Significant wave height, \(\mathrm {[L]}\)

  • ZCWAPE: real: Zero-crossing wave period, \(\mathrm {[T]}\)

For IWASP1=21, JONSWAP spectrum with six parameters

OMEGA ALPHA BETA GAMMA SIGA SIGB

  • OMEGA: real: Peak frequency, \(\mathrm {\omega _p}\), \(\mathrm {[rad}/T]\)

  • ALPHA: real: Spectrum parameter \(\mathrm {\alpha }\)

  • BETA: real, default: 1.25: Form parameter, \(\mathrm {\beta }\)

  • GAMMA: real, default: 3.3: Peakedness parameter, \(\mathrm {\gamma }\)

  • SIGA: real, default: 0.07: Spectrum parameter \(\mathrm {\sigma _a}\)

  • SIGB: real, default: 0.09: Spectrum parameter \(\mathrm {\sigma _b}\)

For IWASP1=22, JONSWAP spectrum with 2 parameters

SIWAHE TPEAK

  • SIWAHE: real: Significant wave height, \(\mathrm {[L]}\)

  • TPEAK: real: Peak period, \(\mathrm {T_p}\), \(\mathrm {[T]}\)

For IWASP1=23, JONSWAP spectrum with 3 parameters

SIWAHE TPEAK GAMMA

  • SIWAHE: real: Significant wave height, \(\mathrm {[L]}\)

  • TPEAK: real: Peak period, \(\mathrm {T_p}\), \(\mathrm {[T]}\)

  • GAMMA: real, default: 3.3: Peakedness parameter, \(\mathrm {\gamma }\)

For IWASP1=24, Double peaked JONSWAP spectrum with 2 parameters (described by Torsethaugen)

SIWAHE TPEAK

  • SIWAHE: real: Significant wave height, \(\mathrm {[L]}\)

  • TPEAK: real: Peak period, \(\mathrm {T_p}\), \(\mathrm {[T]}\)

For IWA5P1=31, Ochi-Hubble spectrum with 1 parameter

SIWAHE

  • SIWAHE: real: Significant wave height, \(\mathrm {[L]}\)

Ref.: M. K. Ochi and E. N. Hubble (1976): Six-parameter Wave Spectra, Coastal Engineering

For IWASP1=100, numerically defined spectrum, 1 input line

NWFRE NWDIR

  • NWFRE: integer: Number of wave frequencies

  • NWDIR: integer: Number of wave directions

For IWASP1=100, 1 input line

WADIR(1) ... WADIR(NWDIR)

  • WADIR: real: Wave propagation direction, \(\mathrm {[deg]}\)

Wave propagation direction (NWDIR+1)/2 is used as average wave direction in DYNMOD in cases where responses are pregenerated in a range around the average direction.

For IWASP1=100, NWAFRE input lines

WAFREi SPVAL(1,i) ... SPVAL(NWDIR,i)

  • WAFREi: real: Wave frequency, \(\mathrm {[rad}/T]\)

  • SPVAL: real: Spectrum value, \([L^2T/\mathrm {rad]}\)

1 identifying input line if IWASP2 != 0.

WAVE SPECtrum SWELl

This data group requires the same data as WAVE SPECtrum WIND.

1 identifying input line if IWASP1 != 100

WAVE DIREction PARAmeters

1 input line

WADIR1 EXKPO1 NDIR1

  • WADIR1: real: Average wave propagation direction, wind sea, \(\mathrm {[deg]}\)

  • EXPO1: real, default: 2: Exponent \(\mathrm {\eta }\) in cos spreading function, wind sea

  • NDIR1: integer, default: 11: Number of directions in spreading function, must be uneven

1 input line if IWASP2 != 0

WADIR2 EXPO2 NDIR2

  • WADIR2: real: Average wave propagation direction, swell, \(\mathrm {[deg]}\)

  • EXPO2: integer, default: 2: Exponent \(\mathrm {\eta }\) in cos spreading function, swell

  • NDIR2: integer, default: 11: Number of directions in spreading function, must be uneven

5. Wind

Wind velocity and direction may be read from an ASCII file. See Reading wind time series from file.

1 identifying input line

WIND SPECification

1 input line

CHWIND

  • CHWIND: character(8): Wind condition identifier

1 input line

 IWITYP

  • IWITYP: integer: Wind type

    • = 1: Davenport spectrum

    • = 2: Harris spectrum

    • = 3: Wills (modified Harris) spectrum

    • = 4: Sletringen spectrum

    • = 5: ISO 19901-1 (NPD) wind spectrum

    • = 6: API wind spectrum

    • = 7: ESDU wind spectrum

    • =10: Stationary uniform wind with shear, values interpolated at grid points

    • =11: Fluctuating uniform 2-component wind

    • =12: Fluctuating 3-component wind read from files (IECWind format)

    • =13: Fluctuating 3-component wind read from files (TurbSim format)

    • =14: Stationary uniform wind with shear

Sletringen and ISO 19901-1 (NPD) wind spectra applies only for extreme wind speeds, typically 1, 10 or 100 year return values.

The API wind spectrum is representing typhoon wind conditions.

The wind types 10-13 are intended for wind turbine analyses. However, they may also be applied for other type of analysis. It should be noted that for these wind types the wind velocity time series will be the same for all bodies in the system.

For the fluctuating 3-component wind (IWITYP=12), only the fluctuating part of the wind is given in the wind input files. The mean wind speed UMVEL given below is added to the yield the total wind velocity in the longitudinal direction. The input files must conform to the 3-dimensional 3-component wind time series from the rectangular IEC format (See Thomsen, K., 2006. Mann turbulence for the IEC Code Comparison Collaborative (OC3). Risø National Laboratory). More specifically they must include time series of wind velocity in binary format, with a 3-dimensional array having indices in vertical direction running fastest, then indices in lateral direction and indices in longitudinal direction running slowest.

For wind files from NREL’s TurbSim (IWITYP=13), the mean wind speed and shear are included in the binary files. The input files must be generated by TurbSim with WrBLFF=True. Both the .wnd file and .sum file are needed.

Wind spectrum parameters for IWITYP = 1,2,3 1 input line.

 WIDIR  ZREF  ALPHWI  WINREF  LEN  FRIC  NZ  Z_MIN  Z_MAX  EXTOP

  • WIDIR: real: Wind propagation direction \(\mathrm {[deg]}\)

  • ZREF: real, default: 10: Reference height for wind velocity \(\mathrm {[L]}\)

  • ALPHWI: real, default: 0.11: Wind profile exponent

  • WINREF: real: Average velocity at ZREF \(\mathrm {[L/T]}\)

  • LEN: real, default: 1200: Reference length of wind turbulence \(\mathrm {[L]}\)

  • FRIC: real, default: 0.002: Surface drag coefficient, dummy for IWITYP=3.

    • Also used for transverse gust spectrum, if specified in DYNMOD

  • NZ: integer, default: 1: Number of levels in vertical domain (only relevant when transverse gust is used in DYNMOD)

  • Z_MIN, real, default: 0.0: Lower limit of vertical domain

  • Z_MAX, real, default: 0.0: Upper limit of vertical domain

  • EXTOP, character(60), default: 'ERROR': Behaviour outside vertical domain

    • ERROR: Computing wind velocity outside specified boundaries causes an error

    • CONSTANT: Wind fluctuations for Z_MIN/Z_MAX is used outside vertical domain

Wind spectrum parameters for IWITYP = 4, 1 input line.

 WIDIR  ZREF  ALPHWI  WINREF  GAMMA  FRIC  NZ  Z_MIN  Z_MAX  EXTOP

  • WIDIR: real: Wind propagation direction \(\mathrm {[deg]}\)

  • ZREF: real: Reference height for wind velocity \(\mathrm {[L]}\), fixed = 10 m

  • ALPHWI: real, default: 0.11: Wind profile exponent, dummy input

  • WINREF: real: 1 hour average velocity at 10 m \(\mathrm {[L/T]}\)

  • GAMMA: real, default: 10: Temperature stability parameter \(\mathrm {[/L]}\)

  • FRIC: real, default: 0.002: Surface drag coefficient (only used for transverse gust spectrum, if specified in DYNMOD)

  • NZ: integer, default: 1: Number of levels in vertical domain

  • Z_MIN, real, default: 0.0: Lower limit of vertical domain

  • Z_MAX, real, default: 0.0: Upper limit of vertical domain

  • EXTOP, character(60), default: 'ERROR': Behaviour outside vertical domain

    • ERROR: Computing wind velocity outside specified boundaries causes an error

    • CONSTANT: Wind fluctuations for Z_MIN/Z_MAX is used outside vertical domain

Wind spectrum parameters for IWITYP = 5, 1 input line.

 WIDIR  ZREF  ALPHWI  WINREF  GAMMA  FRIC  NZ  Z_MIN  Z_MAX  EXTOP

  • WIDIR: real: Wind propagation direction \(\mathrm {[deg]}\)

  • ZREF: real: Reference height for wind velocity \(\mathrm {[L]}\), fixed = 10 m, dummy input

  • ALPHWI: real: Wind profile exponent, fixed = 0.11, dummy input

  • WINREF: real: 1 hour average velocity at 10 m \(\mathrm {[L/T]}\)

  • GAMMA: real: dummy (but must be given)

  • FRIC: real, default: 0.002: Surface drag coefficient (used for transverse gust spectrum, if specified in DYNMOD)

  • NZ: integer, default: 1: Number of levels in vertical domain

  • Z_MIN, real, default: 0.0: Lower limit of vertical domain

  • Z_MAX, real, default: 0.0: Upper limit of vertical domain

  • EXTOP, character(60), default: 'ERROR': Behaviour outside vertical domain

    • ERROR: Computing wind velocity outside specified boundaries causes an error

    • CONSTANT: Wind fluctuations for Z_MIN/Z_MAX is used outside vertical domain

Wind spectrum parameters for IWITYP = 6, 1 input line.

 WIDIR  FREPA  ALPHWI  WINREF  THICK  FRIC  NZ  Z_MIN  Z_MAX  EXTOP

  • WIDIR: real: Wind propagation direction \(\mathrm {[deg]}\)

  • FREPA: real, default: 0.025: Frequency parameter

  • ALPHWI: real, default: 0.125: Wind profile exponent

  • WINREF: real: 1 hour average velocity at 10 m \(\mathrm {[L/T]}\)

  • THICK: real, default: 20: Surface Layer Thickness

  • FRIC: real, default: 0.002: Surface drag coefficient (used for transverse gust spectrum, if specified in DYNMOD)

  • NZ: integer, default: 1: Number of levels in vertical domain

  • Z_MIN, real, default: 0.0: Lower limit of vertical domain

  • Z_MAX, real, default: 0.0: Upper limit of vertical domain

  • EXTOP, character(60), default: 'ERROR': Behaviour outside vertical domain

    • ERROR: Computing wind velocity outside specified boundaries causes an error

    • CONSTANT: Wind fluctuations for Z_MIN/Z_MAX is used outside vertical domain

Wind spectrum parameters for IWITYP = 7, 1 input line.

 WIDIR  WINREF  PSI  NZ  Z_MIN  Z_MAX  EXTOP

  • WIDIR: real: Wind propagation direction \(\mathrm {[deg]}\)

  • WINREF: real: 1 hour average velocity at 10 m \(\mathrm {[L/T]}\)

  • PSI: real: Site latitude in decimal degrees \(\mathrm {[deg]}\)

  • NZ: integer, default: 1: Number of levels in vertical domain

  • Z_MIN, real, default: 0.0: Lower limit of vertical domain

  • Z_MAX, real, default: 0.0: Upper limit of vertical domain

  • EXTOP, character(60), default: 'ERROR': Behaviour outside vertical domain

    • ERROR: Computing wind velocity outside specified boundaries causes an error

    • CONSTANT: Wind fluctuations for Z_MIN/Z_MAX is used outside vertical domain

Wind direction for IWITYP = 10, 1 input line.

WIDIR

  • WIDIR: real: Wind propagation direction, \(\mathrm {[deg]}\)

Wind velocity for IWITYP = 10, 1 input line

UMVEL VMVEL WMVEL

  • UMVEL: real: Longitudinal wind velocity component \(\mathrm {[L/T]}\)

  • VMVEL: real: Lateral wind velocity component \(\mathrm {[L/T]}\)

  • WMVEL: real: Vertical wind velocity component \(\mathrm {[L/T]}\)

The parameters UMVEL and VMVEL refer to the direction given by the WIDIR parameter

Number of levels in shear profile for IWITYP = 10, 1 input line

NZPROF

  • NZPROF: integer: Number of vertical levels for defining the shear profile

Velocity profile definition for IWITYP = 10, NZPROF input lines.

ZLEV  UMFACT  VMFACT  WMFACT

  • ZLEV: real: Vertical coordinate of profile level \(\mathrm {[L]}\)

  • UMFACT: real: Wind speed scaling factor for the longitudinal wind velocity

  • VMFACT: real: Wind speed scaling factor for the lateral wind velocity

  • WMFACT: real: Wind speed scaling factor for the vertical wind velocity

Wind field domain location for IWITYP = 10, 1 input line.

Z0

  • Z0: real: Z coordinate of the lower edge of the wind field domain \(\mathrm {[L]}\)

Domain size for IWITYP = 10, 1 input line.

NZ

  • NZ: integer: Number of grid points in Z- (vertical) direction

Domain resolution for IWITYP = 10, 1 input line.

DLWFZ

  • DLWFZ: real: Domain resolution in Z- (vertical) direction \(\mathrm {[L]}\)

Wind input parameter for IWITYP = 11, 1 input lines.

WIDIR

  • WIDIR: real: Wind propagation direction, \(\mathrm {[deg]}\)

Wind data file name for IWITYP = 11, 1 input line:

CHWF

Mean wind direction for IWITYP = 12, 1 input line.

WIDIR

  • WIDIR: real: Wind propagation direction, \(\mathrm {[deg]}\)

Mean wind velocity for IWITYP = 12, 1 input line.

UMVEL

  • UMVEL: real: Mean wind speed (along WIDIR direction) \(\mathrm {[L/T]}\)

Number of levels in shear profile for IWITYP = 12, 1 input line.

NZPROF

  • NZPROF: integer: Number of vertical levels for defining the shear profile

Velocity profile definition for IWITYP = 12, NZPROF input lines.

ZLEV  UMFACT  UFACT  VFACT  WFACT

  • ZLEV: real: Vertical coordinate of profile level \(\mathrm {[L]}\)

  • UMFACT: real: Wind speed scaling factor for the mean wind speed

  • UFACT: real: Wind speed scaling factor for fluctuating part of the longitudinal wind velocity

  • VFACT: real: Wind speed scaling factor for the lateral wind velocity

  • WFACT: real: Wind speed scaling factor for the vertical wind velocity

Name of file containing the fluctuating longitudinal wind time series, IWITYP = 12, 1 input line

CHWFU

  • CHWFU: character(256): Character string giving path and filename for the fluctuating U-component wind time series

Name of file containing the fluctuating lateral wind time series, IWITYP = 12, 1 input line

CHWFV

  • CHWFV: character(256): Character string giving path and filename for the fluctuating V-component wind time series

Name of file containing the fluctuating vertical wind time series, IWITYP = 12, 1 input line

CHWFW

  • CHWFW: character(256): Character string giving path and filename for the fluctuating W-component wind time series

Wind field domain position for IWITYP = 12, 1 input line.

X0LL  Y0LL  Z0LL

  • X0LL: real: X-coordinate of the lower left corner of the upstream border of the wind field domain \(\mathrm {[L]}\)

  • Y0LL: real: Y-coordinate of the lower left corner of the wind field domain \(\mathrm {[L]}\)

  • Z0LL: real: Z-coordinate of the lower left corner of the wind field domain \(\mathrm {[L]}\)

These three coordinates defines one of the corners of the wind field domain, which is defined as a rectangular cuboid. The coordinates refers to a coordinate system centred at the global origin, with the x-axis (longitudinal direction) pointing in the down-stream mean wind speed direction and the z-axis coincident with the global z-axis.

Domain size for IWITYP = 12, 1 input line.

NX NY  NZ

  • NX: integer: Number of grid points in X- (longitudinal) direction

  • NY: integer: Number of grid points in Y- (lateral) direction

  • NZ: integer: Number of grid points in Z- (vertical) direction

Field size for IWITYP = 12, 1 input line.

LWFX  LWFY  LWFZ

  • LWFX: real: Field size in X- (longitudinal) direction \(\mathrm {[L]}\)

  • LWFY: real: Field size in Y- (lateral) direction \(\mathrm {[L]}\)

  • LWFZ: real: Field size in Z- (vertical) direction \(\mathrm {[L]}\)

Buffer size for IWITYP = 12, 1 input line.

 NSLICE

  • NSLICE: integer, default: 10: Buffer size: Number of wind cross-sectional planes (Slices) in memory

Mean wind direction for IWITYP = 13, 1 input line.

WIDIR

  • WIDIR: real: Wind propagation direction, \(\mathrm {[deg]}\)

Name of binary (.wnd) file containing the TurbSim fluctuating wind time series for IWITYP = 13, one input line

CHWFTW

  • CHWFTW: character(256): Path and filename for the binary TurbSim (.wnd) file

Name of the summary (.sum) file from TurbSim for IWITYP = 13, one input line

CHWFTS

  • CHWFTS: character(256): Path and filename for the summary TurbSim (.sum) file

The wind field domain- and field size are extracted from the TurbSim .sum file.

The wind field domain location in the global coordinate system is not given explicitly by the user. The vertical position of the wind field center is the same as in TurbSim; i.e. taken as the hub height given on the turbsim .sum file.

Horizontally, the wind field is positioned around the global origin, but with a half grid width downwind of the origin. Since the TurbSim wind is non-periodic, this is necessary to ensure that the entire turbine lies in the same part of the wind field at the start of the simulation. The wind at the global origin will thus not start at the first slice

The wind field must be large enough to ensure that the whole structure is within the wind field during the entire simulation. As the TurbSim wind field is nonperiodic, the beginning and end of the wind field will not fit together.

Buffer size for IWITYP = 13, one input line

NSLICE

  • NSLICE: integer, default: 800: Buffer size: Number of wind cross-sectional planes (Slices) in memory

Note: Since TurbSim files are not periodic, time series are shifted by 1/2 Grid Width. The number of slices in memory must be greater than (Grid Width/MeanWindSpeed/WindFileTimeStep).

Wind direction, velocity and shear profile type for IWITYP = 14, one input line

WIDIR UMVEL WMVEL CH_SHEAR

  • WIDIR: real: Wind propagation direction in global XY-plane \(\mathrm {[deg]}\)

  • UMVEL: real: Longitudinal wind velocity component \(\mathrm {[L/T]}\)

  • WMVEL: real: Vertical (global Z-axis) wind velocity component \(\mathrm {[L/T]}\)

  • CH_SHEAR: character(4): Shear profile type

    • NONE - No shear profile

    • POWR - Power shear profile

    • LOGA - Logarithmic shear profile

UMVEL is the wind velocity in the direction WIDIR.

Power shear profile input for IWITYP = 14 and CH_SHEAR = POWR, one input line

ZREF ALPHA

  • ZREF: real: Reference height \(\mathrm {[L]}\)

  • ALPHA: real: Wind shear exponent \(\mathrm {[-]}\)

The power shear profile is given as

\[\bar{u}(z)=\bar{u_r}(\frac{z}{z_r})^\alpha\]

where

\(z\)

height above water plane

\(z_r\)

reference height, normally \(10 ~ \mathrm{m}\)

\(\bar{u_r}\)

average velocity at the reference height \(z_r\) above the calm water level

\(\alpha\)

height coefficient \((0.10 - 0.14)\)

\(\bar{u}\)

average velocity at height \(z\)

Logarithmic shear profile input for IWITYP = 14 and CH_SHEAR = LOGA, one input line

ZREF Z0

  • ZREF: real: Reference height \(\mathrm {[L]}\)

  • Z0: real: Roughness length \(\mathrm {[L]}\)

The logarithmic shear profile is given as

\[\bar{u}(z)=\bar{u_r}(\frac{\ln(\frac{z}{z_0})}{\ln(\frac{z_r}{z_0})})\]

where

\(z\)

height above water plane

\(z_0\)

height for zero wind speed

\(z_r\)

reference height, normally \(10 ~ \mathrm{m}\)

\(\bar{u_r}\)

average velocity at the reference height \(z_r\) above the calm water level

\(\bar{u}\)

average velocity at height \(z\)

6. Current

1 identifying input line

CURRent SPECification

1 input line

CHCURR    L_EXTERN

  • CHCURR: character(8): Current condition identifier

  • L_EXTERN: integer, default: 0: Flag describing if current data is given in this input file, or if it shall be read from a separate file

    • = 0: Data specified in this input file

    • = 1: Data read from external file

For details on the external file format, confer the CURMOD user documentation.

IF L_EXTERN = 0, 1 input line

NCUR

  • NCUR: integer: Number of current levels

IF L_EXTERN = 0, Current parameters, NCUR lines

CURVEL CURDIR CURLEV

  • CURVEL: real: Current velocity, \(\mathrm {[L/T]}\)

  • CURDIR: real: Current propagation direction, \(\mathrm {[deg]}\)

  • CURLEV: real: Global z-coordinate of current level, \(\mathrm {[L]}\)

IF L_EXTERN = 1, 1 input line

CURRFILE

  • CURRFILE: character(120): Name of external file with specified current data