Wave Drift Loads |
 
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Wave Drift Loads |
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The wave drift loads are calculated from user-specified Quadratic Transfer Function (QTF) values according to the following equation:
(1)
where:
•
is one of the three wave drift loads applied to the vessel CoG (i.e. 
, 
, or 
)
•
is the QTF value for relative wave incidence 
(wave direction relative to the instantaneous vessel orientation) and frequency 
for the load direction in question
•
, 
and 
are the amplitude, frequency and phase respectively of the kth wave harmonic
•sign(p) equals -1 if p < 0, 0 if p = 0, and 1 if p >0
The wave drift loads are calculated for every wave frequency present in the (discretised) wave spectrum and for every wave direction. A mean drift load is calculated in Static Mooring analyses to determine the mean vessel position, using the equation:
(2)
where:
•
is one of three mean wave drift loads applied to the vessel CoG (i.e. 
, 
, or 
)
•
is the wave spectrum
and the remaining symbols have the same meanings as above.
•*QTF is used to specify Quadratic Transfer Functions (QTFs) that allow the slow drift loads on a floating body or moored vessel to be determined.
If you would like to see an example of how this keyword is used in practice, refer to D01 - Moored Vessel.