|
TBuoyInstantaneousCalculationData |
|
|
TBuoyInstantaneousCalculationData |
The TBuoyInstantaneousCalculationData contains information about the instantaneous state of a 6D buoy. This information is available for applied load external functions for 6D Buoys.
typedef struct {
int Size;
TVector Position;
TMatrix Orientation;
TVector Velocity;
TVector AngularVelocity;
double ProportionWet;
TVector WettedCentroidPosition;
TVector FluidVelocity;
double FluidDensity;
} TBuoyInstantaneousCalculationData;
Specifies the size, in bytes, of this data structure.
The global axes X,Y,Z coordinates of the position of the buoy origin relative to the global origin.
A matrix containing the orientation of the buoy, relative to global axes. The matrix is in row-major order, so the first 3 elements are the first row, the next 3 the second row and the last 3 the third row. These rows contain the global axes components of the unit vectors in the buoy local x-, y- and z-axes directions: the first 3 elements of the matrix (first row) are the global axes components of the buoy local x-direction, the next 3 elements (second row) are the global axes components of the buoy local y-direction, and the last 3 (third row) are the global axes components of the buoy local z-direction.
The X,Y,Z components in the global axes directions, of the velocity of the buoy origin relative to global.
The x,y,z components in the buoy axes directions, of the angular velocity of the buoy relative to global.
| Note: | This vector is given in buoy axes components, not global axes components. |
The proportion of the buoy that is submerged in the sea. The value is in the range 0 to 1, a value of 0 meaning no submersion and 1 meaning completely submerged.
Available for Lumped Buoys only.
The buoy local axes coordinates of the position of the centroid of the wetted portion of the buoy, relative to the buoy origin. If the buoy is full submerged (ProportionWet=1) then this is the centre of volume as specified in the buoy data form. If ProportionWet is zero then WettedCentroidPosition is zero.
Available for Lumped Buoys only.
The global axes X,Y,Z components of the velocity of the fluid (current and wave combined) relative to global, at the buoy's wetted centroid. If ProportionWet is zero then FluidVelocity is zero.
Available for Lumped Buoys only.
The density of the fluid at the buoy's wetted centroid. If ProportionWet is zero then FluidDensity is zero.
Available for Lumped Buoys only.
This density value is given in units consistent with the model's length and force units. For example suppose that you wished to use the fluid density (ρ) in a drag formula: ½ρAV². If your model uses US units of length=ft, mass=kp and force=kp then the formula ½ρAV² does not give a force in kps. Instead you must use the so called mass density ρ/g = ρ/32.174 so that the drag formula becomes ½(ρ/g)AV².
OrcaFlex internally uses the convention that density values are mass densities so that formulae like ½ρAV² can be written in their natural form. Accordingly the value passed to the external function in TBuoyInstantaneousCalculationData is a mass density and can be used directly in formulae like ½ρAV².
| Note: | The above issue does not arise in OrcaFlex standard SI units of of length=m, mass=te and force=kN because these are a consistent set of units. |
See also