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General

The General tab includes a single frame with several check boxes used to select the main types of components to be included in the Environment Set. Activating any of the check boxes raises additional sheets in the Environment Set data form. These sheets are to be used to further specify data related to the individual components.

Individual components types are as follows:

Environment components: These components include all environmental conditions including waves, winds and currents. A maximum number of 3 distinct waves trains can be setup and further combined in the same analysis.
- Main swells: These components define the first set of individual waves. Individual waves may be either regular or irregular waves. Although the name explicitly refers to main swells, these components can be used to model swells or wind seas.
- Secondary swells: These components define the second set of individual waves. Individual waves may be either regular or irregular waves. Although the name explicitly refers to secondary swells, these components can be used to model swells or wind seas.
- Local seas: These components define the third set of individual waves. Individual waves may be either regular or irregular waves. Although the name explicitly refers to local seas, these components can be used to model swells or wind seas.
- Winds: These components define the set of wind data. Wind components may be defined through a spectrum or through the wind velocity history to model squalls.
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 through the *BARCAIR keyword (applicable to bar and cable elements) or the *BEAMCAIR keyword (applicable to beam elements).
Currents: These components define the set of current profiles. Current profiles may be varied function of the quasi-static analysis step. Unless standard current profiles included in the current data form, these components can not be set to vary function of time.
Prescribed motion: These components include all quasi-static and dynamic prescribed motions that apply to structural model components such as lines, rigid bodies, buoys, and floaters. The number of distinct prescribed motion sets can be specified to allow for multiple prescribed motions to be combined within the same analysis.
- Quasi-static motion: These components define the set of quasi-static motion to be applied on structural model components. Each quasi-static motion is defined through the translations along the XYZ global axes and rotations about the XYZ global axes. Use of these quasi-static motion components is restricted to quasi-static analyses.
- Dynamic motion: These components define the set of dynamic motion to be applied on structural model components. Each dynamic motion is defined through an external text-based file which describes the motion as a function of time. Use of these dynamic motion components is restricted to dynamic analyses in the time-domain and cannot be used with dynamic analyses in the frequency domain.
Note

Prescribed motion will actually apply on selected nodes in the model provided that these nodes are anchored using a "constraint" boundary condition. The effects of prescribed loadings would be cancelled in case the nodes to which the motion is expected to apply is left free (this is also valid in case the node is assigned a "fully blocked" boundary condition), or in case the node is connected to another model component (with the node being already slave of another node in the model).
Prescribed loadings: These components include all quasi-static and dynamic prescribed loadings that apply to structural model components such as lines, rigid bodies, buoys, and floaters. The number of distinct prescribed loading sets can be specified to allow for multiple prescribed loadings to be combined within the same analysis.
- Quasi-static loadings: These components define the set of quasi-static loadings to be applied on structural model components. Each quasi-static loading is defined through the forces along the global or local XYZ axes and moments about the global or local XYZ axes. Use of these quasi-static loadings components is restricted to quasi-static analyses.
- Dynamic loadings: These components define the set of dynamic loadings to be applied on structural model components. Each dynamic loading is defined through an external text-based file which describes the loading along the 6 degrees of freedom as a function of time. Loadings may be specified using the global coordinates system or the local coordinates system. Use of these dynamic loading components is restricted to dynamic analyses in the time-domain and cannot be used with dynamic analyses in the frequency domain.
Note

Prescribed loadings will actually apply on selected nodes in the model provided that these nodes are left free to move under the effect of the prescribed loadings. The effects of prescribed loadings would be cancelled in case a boundary condition applies to the nodes to which the loadings is expected to apply (e.g. if the node is anchored or linked to another model component).
Floater motion: These components include sets of quasi-static and dynamic motion that are to be applied on floater components.
- Offsets: These components define the set of vessel offsets (i.e. floater quasi-static excursion) that are to be applied on floater components. Each offset component is defined through the its heading and amplitude. Yaw motion may also be specified. Offsets may apply at the reference point of the floater, or at any existing fairlead/hang-off point. This allows for instance modelling floater rotation about the turret centre for turret moored vessels.
Note

Quasi-static offsets may apply on floaters provided the Floater motion type associated with the Floater component is not calculated by the FE engine as with coupled mooring analyses.
- Low frequency imposed motion: These components define the set of low frequency motion that apply on floater components. Low frequency motion is a special type of prescribed motion featuring harmonic motion along the 6 degrees of freedom (i.e. the low frequency motion is not calculated part of the dynamic analysis and is directly prescribed).
Note

Low frequency motion may apply on floaters provided the Floater motion type associated with the Floater component is not calculated by the FE engine as with coupled mooring analyses.
- Floater motion: These components are used to assign selected Floater motion types to existing Floaters components. Selection of floater motion type to be considered along with other combined environmental conditions can be made in the Combination matrix tab. The floater motion type that is selected will supersede the default floater motion type that is setup in the Floater data form. This feature is useful to setup load case matrices featuring various dynamic responses of the floater (e.g. with part of the analyses being conducted with a certain vessel draft and associated motion RAO, and another part of the analyses being conducted with another vessel draft and associated motion RAO).
Warning

Floater motion components can be setup in the Environment Sets provided at least one Floater component is already included in your model.
Turbine options: This component is used to assign selected wind turbines properties types to existing hawt components.
User Defined Keyword: This component is used to add solver keywords as explained in User Defined Keywords section.

Note

The checkboxes behave independently, i.e. several checkboxes may be activated at the same time.

As a checkbox is activated (respectively non activated) by the user, the corresponding tab is set visible (respectively invisible). For instance, when activating the Swell checkbox, the Swell tab becomes visible to the user. The default state of the checkboxes is not activated.

An example of General tab is presented below: