Learning Forum

[Grigor]

Hi

i would like to ask does ANSYS AQWA include gravitational correction in calculations

regards Grigor

[Rob]

It does include gravity, not sure what you mean by gravitational correction. knows more.

[Mike Pettit]

Can you be more specific in what you mean by gravitational correction?
Cheers, Mike

[Grigor]

The accelerations normaly are given in the ship-fixed coordinate system. Beside the dynamic accelerations excited by the waves, the accelerations include also the acceleration due to the gravity. Thus, the longitudinal accelerations contain the influence of the gravity component caused by the pitch motions [g├ùsin╬©]. The predicted lateral accelerations include mainly the influence of the gravity component caused by the roll motions [g├ùsin¤ò├ùcos╬©]. And the vertical accelerations contain the very small influence of the gravity component caused by the pitch motions and the small influence of the gravity component caused by the roll motions [g├ù(1-cos¤ò├ùcos╬©)].
tnx in advance

[Mike Pettit]

Thanks for the clarification. Aqwa results are mostly reported in the global coordinate system ('fixed reference axes'), and would need to be transformed into the vessel coordinate system ('local structure axes') in post-processing.
However, in a frequency statistical Hydrodynamic Response analysis it is possible to output results in the local structure axes. Nodal accelerations do not include the gravity component, but you can use the approach described in Section 14.1 of the Aqwa Theory Manual to evaluate this. An option to include gravity in frequency statistical nodal accelerations will be added in Release 2022 R2.
Cheers, Mike

[Grigor]

Tnx for clarification
will be used
looking forward for new release
regards Grigor