Bureau Veritas (BV) has introduced new software for analysis of mooring lines and floating platform behavior. Cable 3D is a fast, non-linear 3D finite element package which provides static and time domain analysis of mooring lines and flexible risers. It also enables simulation of dynamic structure response caused by regular waves or random seas, with or without current.
BV is incorporating Cable 3D into its Ariane suite as a post-processor, as time domain analysis of line dynamics is typically more time-consuming than simulating overall mooring system behavior. This means that the user will first have to perform a time domain analysis that takes into account the low frequency response of the vessel, and then select a line for dynamic analysis.
Ariane 3D will impose on the fairlead of the selected line the motions calculated by the previous time domain analysis, in order to compute wave and current loads on the lifted part of the line as well as the tangential and transverse friction effect on the laid-down part of the line at each time step.
BV has also enhanced Diodore, the hydrodynamic module of its Oceanos suite for floater behavior modeling. A pre-design method has been introduced for multi-column structures such as TLPs or semisubmersibles. This is said to be a fast and accurate, semi-analytical method for computing 1st order wave load and horizontal drift forces. Non-linearities in the wave crest can be taken into account.
BV has also improved its time domain simulation modules for moored structures. For the low frequency module, improvements include:
- LF hydrodynamic load with full QTF or with Newman approximations
- specific features for TLP motions in the vertical plane (& Morison load on tether and risers)
- complex connection capabilities between structures, such as turrets
- computation of LF damping including wave drift and mooring line damping
- connection with the Ariane mooring program for use of complex mooring line characteristics.
For the non-linear frequency wave module, newly available is full multi-body non-linear wave frequency time domain simulation, including:
- non-linear hydrostatic (remeshing at each step)
- memory effect on the radiation forces
- non-linear forces in the wave crest (stretching method) - complex connection between structures and mooring capabilities.
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