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*Point Buoy |
 
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*Point Buoy
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*Point Buoy |
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To define point buoys and their associated hydrodynamic properties.
Refer to Point Masses and Point Buoys for further information on this feature.
A block of lines used to define a point buoy and its properties, repeated as often as necessary. The block begins with an optional line indicating that rotational terms are being specified. The next line contains the node number, buoyancy, weight, and (optionally) rotational inertia terms and a local axis system. If any of the rotational terms are specified, 6 more lines are required to complete the block. Otherwise 3 more lines are expected.
[OPTION=6D_BUOY]
Node (Number or Label), Total Buoyancy, Total Weight [, Ixx] [, Iyy] [, Izz] [, AXIS=Axis Name]
X:CdAd, X:CmVin, X:CaVin
Y:CdAd, Y:CmVin, Y:CaVin
Z:CdAd, Z:CmVin, Z:CaVin
[X:CdDMA, X:CmHI, X:CaHI]
[Y:CdDMA, Y:CmHI, Y:CaHI]
[Z:CdDMA, Z:CmHI, Z:CaHI]
You must use the *LOCAL AXIS SYSTEM keyword to define any local axis system you reference here. If you specify a node label rather than a node number, it must be enclosed in {} brackets.
To define a 3D point buoy.
Input: |
Description |
Node: |
The node (number or label) at which the point buoy is to be positioned. If you specify a node label rather than a node number, it must be enclosed in {} brackets. |
Total Buoyancy: |
The total buoyancy provided by the buoy. See Note (b). |
Total Weight: |
The total weight (in air) of the buoy. See Note (b). |
Buoy ID (Translational): |
An identifier or name for the buoy, to be used again when specifying the buoy translational hydrodynamic properties using the Buoy Properties – Translational (3D) table. |
(a)This facility is available to include the effect of a subsea buoy in a model. It is intended as an alternative to modelling the buoy explicitly using beam elements. Using this facility also allows you to specify the buoy hydrodynamic properties independently for the different directions.
(b)The net buoyancy provided by the buoy is naturally the difference between the Total Buoyancy and the Total Weight values you specify, while the Total Weight also defines the inertia contribution of the buoy.
To specify translational hydrodynamic properties for 3D point buoys.
Input: |
Description |
Buoy ID: |
The name or ID of the buoy whose translational hydrodynamic properties are being defined. This is also used when defining the buoy itself using Point Buoys – 3D. |
X: CdAd: |
The product of the buoy frontal area and drag coefficient in the global X direction. |
X: CmVin: |
The product of the buoy reference volume and inertia coefficient in the global X direction. |
X: CaVin: |
The product of the buoy reference volume and added mass coefficient in the global X direction. |
Y: CdAd: |
The product of the buoy frontal area and drag coefficient in the global Y direction. |
Y: CmVin: |
The product of the buoy reference volume and inertia coefficient in the global Y direction. |
Y: CaVin: |
The product of the buoy reference volume and added mass coefficient in the global Y direction. |
Z: CdAd: |
The product of the buoy frontal area and drag coefficient in the global Z direction. |
Z: CmVin: |
The product of the buoy reference volume and inertia coefficient in the global Z direction. |
Z: CaVin: |
The product of the buoy reference volume and added mass coefficient in the global Z direction. |
To define a 6D point buoy.
Input: |
Description |
Node: |
The node (number or label) at which the point buoy is to be positioned. If you specify a node label rather than a node number, it must be enclosed in {} brackets. |
Total Buoyancy: |
The total buoyancy provided by the buoy. See Note (b). |
Total Weight: |
The total weight (in air) of the buoy. See Note (b). |
Buoy ID (Translational): |
An identifier or name for the buoy, to be used again when specifying the buoy translational hydrodynamic properties using the Buoy Properties – Translational (6D) table. |
Buoy ID (Rotational): |
An identifier or name for the buoy, to be used again when specifying the buoy rotational hydrodynamic properties using the Buoy Properties – Rotational (6D) table. |
Axis: |
The name of a local axis system to be used in the computation of rotational hydrodynamic loading on the buoy. This entry is optional and the global axis system is used by default. |
Ixx: |
The rotational inertia about the local x-axis for the buoy. This entry is optional and defaults to zero if omitted. |
Iyy: |
The rotational inertia about the local y-axis for the buoy. This entry is optional and defaults to zero if omitted. |
Izz: |
The rotational inertia about the local z-axis for the buoy. This entry is optional and defaults to zero if omitted. |
(a)This facility is available to include the effect of a subsea buoy in a model. It is intended as an alternative to modelling the buoy explicitly using beam elements. Using this facility also allows you to specify the buoy hydrodynamic properties independently for the different directions.
(b)The net buoyancy provided by the buoy is naturally the difference between the Total Buoyancy and the Total Weight values you specify, while the Total Weight also defines the inertia contribution of the buoy.
(c)If a local axis system referenced, it must be defined using the Local Axes table.
To specify translational hydrodynamic properties for 6D point buoys.
Input: |
Description |
Buoy ID: |
The name or ID of the buoy whose translational hydrodynamic properties are being defined. This is also used when defining the buoy itself using Point Buoys – 6D. |
X: CdAd: |
The product of the buoy frontal area and drag coefficient in the global X direction. |
X: CmVin: |
The product of the buoy reference volume and inertia coefficient in the global X direction. |
X: CaVin: |
The product of the buoy reference volume and added mass coefficient in the global X direction. |
Y: CdAd: |
The product of the buoy frontal area and drag coefficient in the global Y direction. |
Y: CmVin: |
The product of the buoy reference volume and inertia coefficient in the global Y direction. |
Y: CaVin: |
The product of the buoy reference volume and added mass coefficient in the global Y direction. |
Z: CdAd: |
The product of the buoy frontal area and drag coefficient in the global Z direction. |
Z: CmVin: |
The product of the buoy reference volume and inertia coefficient in the global Z direction. |
Z: CaVin: |
The product of the buoy reference volume and added mass coefficient in the global Z direction. |
To specify rotational hydrodynamic properties for 6D point buoys.
Input: |
Description |
Buoy ID: |
The name or ID of the buoy whose rotational hydrodynamic properties are being defined. This is also used when defining the buoy itself using Point Buoys – 6D. |
X: CdDMA: |
The product of the drag coefficient and the drag moment of area in the X direction. |
X: CmHI: |
The product of the inertia coefficient and the hydrodynamic inertia in the X direction. |
X: CaHI: |
The product of the added mass coefficient and the hydrodynamic inertia in the X direction. |
Y: CdDMA: |
The product of the drag coefficient and the drag moment of area in the Y direction. |
Y: CmHI: |
The product of the inertia coefficient and the hydrodynamic inertia in the Y direction. |
Y: CaHI: |
The product of the added mass coefficient and the hydrodynamic inertia in the Y direction. |
Z: CdDMA: |
The product of the drag coefficient and the drag moment of area in the Z direction. |
Z: CmHI: |
The product of the inertia coefficient and the hydrodynamic inertia in the Z direction. |
Z: CaHI: |
The product of the added mass coefficient and the hydrodynamic inertia in the Z direction. |