Learning Forum

[Erhan Sokmn]

Hi,

I’m currently studying on a full scale ship model to obtain the roll RAO values. Unfortunately i don’t have the experimental data of Roll RAO for full scale ship. I have the scaled ship’s roll RAO values and thus, i study on scaled ship. RAO values i obtained by scaled ship is too high (around 2500) . When i divide it to the scale amount of the ship, results are getting more meaningful. Is it something convenient to do ?

How can i have the wave amplitude data in hydrodynamic diffraction in AQWA?

My question is,
How can i evaluate roll RAO values of a scaled ship on Ansys AQWA?

Regards,
Erhan.

[Yu Bi]

Hi, Erhan,

You need to use Froude scaling to convert all the dimensional values, e.g. mass, length, frequency, stiffness, force, RAOs, etc, when setting up the model in the Aqwa and comparing the results if its scale is different from the experimental model. For example, the rotational RAO has a length unit in its unit, therefore we need to do a length scaling to it, i.e., Full-scale roll RAO = scaled ship roll RAO/length scale, where length scale>1. 

The coefficients and RAO results in Hydrodynamic Diffraction are calculated under unit wave amplitude (e.g. 1 meter if you use meter as the length unit). 

Regards,

Yu

 

 

[Erhan Sokmn]

Thank you so much for the satisfying answer.