Winds

The wind is defined by the following parameters:

Name: Enter the name of the Wind component.
Wind heading (deg): This sets the heading (flowing direction) of the wind . Headings are defined for the "to" direction with respect to the global X-axis of the model.
Average velocity over a defined time period at the point of interest (m/s)
Wind type, to be selected among the following items:
- Constant: the wind velocity is constant.
  - Heading /X: The heading (flowing direction) of the wind . Headings are defined for the "to" direction with respect to the global X-axis of the model.
  - Velocity: Defines the constant wind velocity.
- Harris: the wind velocity follows an Harris spectrum. Input data required to define this wind type are as follows:
  - Heading /X: The heading (flowing direction) of the wind . Headings are defined for the "to" direction with respect to the global X-axis of the model.
  - Mean velocity 10 min: Mean wind velocity averaged over 10 min.
  - Number of components: this sets the number of wind harmonic components used to model the wind spectrum. This number of components must be at least 100 (default value) to ensure accurate modeling of the wind energy distribution along frequencies.
  - Random procedure trigger: Phases associated with each wind component are pseudo-random. Phases are generated with a random number generator which requires a certain random procedure trigger (also named "seed") to be user-specified. The trigger value must be an odd integer value with 5 digits (the default value is 11111). Two dynamic simulations based on the same trigger value would generate similar phase series.
- Davenport: the wind velocity follows a Davenport spectrum. Input data required to define this wind type are as follows:
  - Heading /X: The heading (flowing direction) of the wind . Headings are defined for the "to" direction with respect to the global X-axis of the model.
  - Mean velocity 10 min: Mean wind velocity averaged over 10 min.
  - Number of components: this sets the number of wind harmonic components used to model the wind spectrum. This number of components must be at least 100 (default value) to ensure accurate modeling of the wind energy distribution along frequencies.
  - Random procedure trigger: Phases associated with each wind component are pseudo-random. Phases are generated with a random number generator which requires a certain random procedure trigger (also named "seed") to be user-specified. The trigger value must be an odd integer value with 5 digits (the default value is 11111). Two dynamic simulations based on the same trigger value would generate similar phase series.
- API: the wind velocity follows an API spectrum. Input data required to define this wind type are as follows:
  - Heading /X: The heading (flowing direction) of the wind . Headings are defined for the "to" direction with respect to the global X-axis of the model.
  - Mean velocity 1 hour: Mean wind velocity averaged over 1 hour.
  - Number of components: this sets the number of wind harmonic components used to model the wind spectrum. This number of components must be at least 100 (default value) to ensure accurate modeling of the wind energy distribution along frequencies.
  - Random procedure trigger: Phases associated with each wind component are pseudo-random. Phases are generated with a random number generator which requires a certain random procedure trigger (also named "seed") to be user-specified. The trigger value must be an odd integer value with 5 digits (the default value is 11111). Two dynamic simulations based on the same trigger value would generate similar phase series.
- Squall: This wind type models a squall wind event defined through time-history of wind velocity. A variation of the velocity and the heading of the wind can be taken into account through an external file. See the *SQUALLWIND keyword for details on the external file format.
- NPD: the wind spectrum follows an NPD (Norwegian Petroleum Directory) spectrum. Input data required to define this wind type are as follows:
  - Heading /X: The heading (flowing direction) of the wind . Headings are defined for the "to" direction with respect to the global X-axis of the model.
  - Mean velocity 1 hour: Mean wind velocity averaged over 1 hour.
  - Number of components: this sets the number of wind harmonic components used to model the wind spectrum. This number of components must be at least 100 (default value) to ensure accurate modeling of the wind energy distribution along frequencies.
  - Random procedure trigger: Phases associated with each wind component are pseudo-random. Phases are generated with a random number generator which requires a certain random procedure trigger (also named "seed") to be user-specified. The trigger value must be an odd integer value with 5 digits (the default value is 11111). Two dynamic simulations based on the same trigger value would generate similar phase series.
- Kaimal: the wind velocity follows an Kaimal spectrum. Input data required to define this wind type are as follows:
- Heading /X: The heading (flowing direction) of the wind . Headings are defined for the "to" direction with respect to the global X-axis of the model.
- Mean velocity 10min: Mean wind velocity averaged over 10 min.
- Number of components: this sets the number of wind harmonic components used to model the wind spectrum. This number of components must be at least 100 (default value) to ensure accurate modeling of the wind energy distribution along frequencies.
- Random procedure trigger: Phases associated with each wind component are pseudo-random. Phases are generated with a random number generator which requires a certain random procedure trigger (also named "seed") to be user-specified. The trigger value must be an odd integer value with 5 digits (the default value is 11111). Two dynamic simulations based on the same trigger value would generate similar phase series.
- Coefficient A: A-coefficient used in the Kaimal wind spectrum equation.
- Coefficient B: B-coefficient used in the Kaimal wind spectrum equation.
- FF Wind: This wind type models a full field turbulent wind defined through time-history of wind velocity. Input data required to define this wind type are as follows:
- Heading /X: The heading (flowing direction) of the wind . Headings are defined for the "to" direction with respect to the global X-axis of the model.
- File: Path and name of the external file used to define the wind data. A full turbulence field is read by DeepLines. The input data consists either of a .sum file (ASCII) and a .wnd file (binary) or a single .bts file (binary). This file is generated by a wind generating software. DeepLines points to the binary file. Both files should be in the same directory.
- Reference position /X: Origin of the file axis in DeepLines Global frame (X direction)
- Reference position /Y: Origin of the file axis in DeepLines Global frame (Y direction)
- Time for mirror effect: If the windfile is too short in duration compared to the simulation time, it is possible to use a mirror effect whereby the wind file is played back and forth over the whole simulation time. On the first Time for mirror effect seconds of the simulation, the wind file is used, then it is played backwards over another Time for mirror effect seconds and so on. Only Time for mirror effect seconds of the windfile is used therefore the variable Time for mirror effect should be smaller than the windfile simulation time.
- HH Wind: This wind type models a hub height wind defined through time-history of wind velocity. Input data required to define this wind type are as follows:
- Heading /X: The heading (flowing direction) of the wind . Headings are defined for the "to" direction with respect to the global X-axis of the model.
- File: Path and name of the external file used to define the wind data. The path to the ASCII file containing the data is provided. See the *WINDFILE keyword for details on the external file format.
- Reference position /X: Origin of the file axis in DeepLines Global frame (X direction)
- Reference position /Y: Origin of the file axis in DeepLines Global frame (Y direction)
- Reference height: Reference Height of the file (usually hub height).
- Width: Horizontal extend of the wind velocity data included in the file.
- Steady wind: This wind type models a steady wind profile with the velocity and heading being defined function of the height above the sea-level. Input data required to define this wind type are as follows:
- Quasi-static evolution: Selects the quasi-static loading table. Set the quasi-static evolution to Constant to account for permanent wind loads since the start of the quasi-static analysis. Select Linear evolution to progressively apply the wind loads between the initial and final quasi-static steps of the analysis. Select user-defined evolution to define the ratio of wind velocity that is accounted for as a finction of the quasi-static analysis step.
- Dynamic evolution: Select either Constant or Variable to define a permanent or variable wind profile. Variable wind profile is defined through series of wind profiles defined at different time values.
- Steps: Number of vertical positions used to define the wind profile.
- Height from sea-level / Velocity / Heading: use this table to define the wind profile, i.e. wind velocity and heading as a function of the height above the sea-level.

Warning

Wind loads primarily apply on floater components within coupled mooring analyses. Wind loads have no effect on line components unless drag coefficients in air are specified in the Line Segment type.

Wind spectrum Details :

The next Table provides details on the available wind energy spectra:

: Wind energy spectrum function
: Gust factor
: Mean velocity at z=10m above sea level
: Mean velocity at elevation z
: Normalised frequency
: Turbulence intensity
: RMS Velocity

Spectrum
HARRIS	Cd = 0.003 ()	averaged on 10 min	-	-	L V =1800m	-
DAVENPORT	Cd = 0.00044	-	averaged on 10 min	-	L V =1200m	-
API	A=40 B=60	averaged on 1 hour				p=0.125 for z < 20m p=0.275 for z >20m
NPD	A=320 n=0.468	averaged on 1 hour	-	-	B=172	-
KAIMAL	A=33.3 B=50	-	averaged on 10 minutes			and z0=0.005 in open sea (z0 rugosity length)