RAO from Nemoh data

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ThiagoMarinho

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I need to produce an RAO and looking through nemoh's source code it seems that it does provide an RAO in post processing but the closest I could find was an excitation force RAO. I'm about to go through the route of generating the RAO from the added mass and damping coefficients, but even that is not trivial as the data output header is quite ambiguious.

Is there anyone here who has been able to extract RAO data from nemoh results that could share some insight with me?

Kind regards,
Thiago
 
Have you try the Nemoh team "contact us" directly :
CONTACT US
For questions, comments or bug reports, please leave a post on NEMOH’s forum: http://lheea.ec-nantes.fr/redmine/projects/nemoh . You must register first (http://lheea.ec-nantes.fr/redmine/account/register). In case of problems with your account activation, please send an email to adrien.grellier@ec-nantes.fr

For other queries, you may contact Dr. Aurélien Babarit, 95cac7f8-a20e-4da8-9814-7132214faf63@ec-nantes.fr" class="lien_externe">aurelien.babarit@ec-nantes.fr
 
I've tried the forum, but apparently it is offline as I get an error when clicking the link. I'll try emailing Aurelien directly. Thanks for the tip.
 
Hi,
I am also trying to obtain RAO data from NEMOH Results. Could you solve it?
Could anyone here help?
 
Ais said:
Hi,
I am also trying to obtain RAO data from NEMOH Results. Could you solve it?
Could anyone here help?
Click to expand...

Hello mate,

I have not written a manual on it. The values are given in dimensional format.

Added mass and damping from RadiationCoefficients.tec
Excitation from ExcitationForce.tec

RAO equation
RAO[i,:] = exc[:,i,0] / np.sqrt(np.power(freq_rad,2)*np.power(Brad[i,:],2) + np.power(-1*np.power(freq_rad,2)*(M+Arad[i,:])+C,2))
Arad = Addded mass coefficients
Brad = Damping coefficients
exc = Excitation forces
M = Inertia matrix
C = Restoring coefficient Matrix
freq_rad = frequency vector
i = DOF index

let me know if this is enough. If you speak python I can send you a script.
 
Thank you so much. I shall try this. Kindly send me the python script also, either here or to my mail id aiswariaaa@gmail.com.
 
Last edited:
Hi,
Could you please explain, from where or how you have got 'C = Restoring coefficient Matrix', values?
Also, it will be really helpful if you provide me with the python script to my email id aiswariaaa@gmail.com.

Thank you so much,
 
Hi Thiago.

I know a few about Nemoh's RAO. I have some routines at Matlab/Octave that allow me to calculate the RAO from one submerged body at Nemoh. I put a RAO figure on this site, but it is still pending moderator approval to be posted.

ThiagoMarinho said:
I need to produce an RAO and looking through nemoh's source code it seems that it does provide an RAO in post processing but the closest I could find was an excitation force RAO. I'm about to go through the route of generating the RAO from the added mass and damping coefficients, but even that is not trivial as the data output header is quite ambiguious.

Is there anyone here who has been able to extract RAO data from nemoh results that could share some insight with me?

Kind regards,
Thiago
Click to expand...
 
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