Sorry for the software-specific info, but hope it helps someone.Ĭlick to expand.A disclaimer. The natural periods for each model component is listed in a table.Ĭ) Artificial short period oscillations (0.01s) are likely due to short line segments or high stiffness values in components such as lines, winches, or seabed where lines touch.ĭ) You can animate any of the modal oscillations in Results > Modal Analysis to get more insight into them, 7.
6.4.6ī) You can get the natural period of all components of your model by calculating the statics (Calculation > Single Statics), then Results > Full Results > All Objects. For explicit time integration, consider adding numerical damping via 'Line Target Damping'. Numbers refer to sections of the manual.Ī) Implicit time integration includes numerical damping, and should be the first choice for stable simulations. Some more information on high-frequency modes in OrcaFlex, so other users can learn from my 'experience' (mistakes). Useful OrcaFlex tips for spurious high-frequency oscillations I would have thought there is the ability to add damping to make the calculations stable, though then the amount of damping which stabalizes the calculations without too much impact on the solution has to be determined. And based on a quick look at the OrcaFlex website it appears to be suitable software, though having to use time steps based on natural period of individual elements is surprising to me.
None of this is intended as a comment on floating and his knowledge or ability. Good data into good software which is the wrong software for the job = garbage out.
#ORCAFLEX THEORY MANUAL HOW TO#
There are a lot of educated people with degrees, some advanced, who believe that all which is needed for an engineering analysis is running computer software, and the only knowledge which is required is how to enter input.
I have to disagree with gonzo about the uneducated people. I should have added a smilely face which I'll do.