Does anybody know whether CAESAR II is able to calculate natural frequencies under water or not?

Thank's a lot

Yes, but the "added mass" contribution of the fluid is not included.

Thank you Richard. May you please tell:

1- Where we identify the surrounding fluid whether it's Air or Water?
2- Where can we include added mass contribution of the fluid?

Best Regards
Hamed

From "Recommended Practice DNV-RP-D101, October 2008, Page 30" :
Added mass ma = Ca*( Rho* Pi/4*D*D )
Rho Density
D = outside diameter
Ca = 1,0 for pipe

Thank you Richard and Ohliger

How do we calculate the natural frequencies in water? I mean where do we identify the invironment (water or air) for the software?

Best Rgards
Hamed

Dear Hamed,

you can not specify the environment in CII. instead, you can insert a unifrom load in your static input equivalent of the added mass suggested by Ohliger.

Thank you Dear Pooria. You are Persian I'm proud of you my dear friends in all around the world. I've just started subsea and during last 14 years I've been working onshore projects. Good luck. Thank you every body.

Thanks Hamed hope to see you around one day

No, no, no !
Uniform Loads are loads and not mass in Caesar 2 dynamic !
Natural freguencies do not change with uniform loads !
One way is : Set a virtuell isolation ( thickness and secific weight)
that equal this fiktive added mass.
But do mind, that your weight load case is then to big (added mass).

Dear Ohliger,

I have to disagree, in a supported piping system with friction, uniform load would play an influential role on the natural frequencies.
I forgot to note out in my previous reply that the buoyancy effect has to be taken off the uniform load in order to have a more accurate result.