Learning Forum

[Gabriele]

Hello,

I have a question regarding the modelling in presence of internal fluid tanks in AQWA...

When there are only solid masses, my understanding is that the reference point for hydrodynamics (addedd masses, damping, generalized forces) is the global centre of gravity (please correct me if I'm wrong).

However, in case there are fluid tanks in the model, I could not find specific information on which point is used as reference. 

The Hydrostatic summary reports information on the position of the "Structure Center of Gravty (CoG)" (only solid masses) and of the "Combined Center of Gravty (CoG)" (fluids + solid masses). 

Which one, if any, of the two is used as reference? The "Combined" one?

If none of the two is used, then which point is used?

Thanks,

Gabriele

[Shuangxing Du]

When there are internal tanks defined with a structure, the motions and total added mass/damping/hydrostatic stiffness matrices and generalised forces are with respect to the rigid body motions at the combined center of COG, which is defined by Equation (3.25) in 3.4.1. Local Internal Tank Axes and Combined COG. 

[Gabriele]

Dear Shuangxing Du,

thank you for the clarification!

Gabriele

[Shuangxing Du]

Hi Gabriele,

You are welcome.

Shuangxing