Learning Forum

[Karim Hussein]

Hi, 

Can I find the natural modes of a moored floating structure in any output file, or is the only way to exract it from from the workbench?

Many thanks,

Karim

[Mike Pettit]

Hi Karim,

Quick answer - no, the only way is to extract from Workbench.

More specifically, we do output the undamped natural modes of the freely-floating structure in still water, and you can find these at the bottom of the Hydrodynamic Diffraction LIS file (e.g. project_files\dp0\AQW\AQW\AQ\Analysis\ANALYSIS.LIS). These do not account for the mooring system, though.

The Natural Modes results you find in a Hydrodynamic Diffraction or Hydrodynamic Response Stability Analysis are running their own post-processing calculations to determine the natural modes of the system. Because the added mass and radiation damping are frequency-dependent, we need to scan through a whole range of frequencies to find the natural modes - this is what the 'mode match indicator' graph is showing. This scanning capability only exists in Aqwa Workbench.

I hope this helps!

Mike

[Karim Hussein]

Hi Mike, 

Many thanks for the clarification!

Karim