Hi,
I would like to design an offshore floating wind turbine farm with Fast. I am using Moses software to do the hydrodynamic computations.
I would like to generate the needed files for hydrodyn ( file.1 file.3 file.hst ) . Does anyone know how to convert the Moses files into Wamit format in order to be able to use it in hydrodyn ?
Thanks for your help.
Regards,
Romain
Dear Romain,
I’m not sure whether MOSES can directly output to the WAMIT output format needed by FAST’s HydroDyn module, but if not, it should not be hard to convert to WAMIT output format yourself—the format of the WAMIT-generated output files (*.1, *.3, and *.hst, etc.) can be found in Chapter 4 of the WAMIT User’s Manual, available online: wamit.com/manual6.4/Chap4.pdf.
Best regards,
Dear Jason,
Thank you for your answer. It helps.
I have another question :
How does WAMIT define the period distribution used in the files ( *.1 *.3 ) ? Does it matter for FAST the number of period for which the calculation are done ? I am limited to 200 periods for the calculation in MOSES… However the model file I have got has more than 500 different periods ( semi model provided with FAST).
Same question with the wave headings.
Best regards,
Romain
Dear Romain,
In WAMIT, the period/frequency and wave-heading discretization are user-defined inputs.
The HydroDyn module of FAST doesn’t require a specific discretization for the frequency- and wave-heading resolution of the frequency-domain potential-flow input, but some guidance is provided in Section 6.8.4 of the draft HydroDyn User’s Guide and Theory Manual: wind.nrel.gov/nwtc/docs/HydroDyn_Manual.pdf. Obviously, you’ll want to capture the physical characteristics of the input and the resolution requirement will depend on the nature of the platform. I would expect a coarse resolution would be sufficient for a simple cylinder whereas a finer resolution would be required for a complex-shaped semi-submersible.
Best regards,
Dear Jason,
Thank you for your usefull help.
Romain
Dear Jason,
I am wondering how HydroDyn deals with the case that the simulated wave headings are not included in the .3 or .12 file? Is it based on interpolation or the principle of proximity?
Best regards,
Shengtao
Dear Shengtao,
HydroDyn will linearly interpolate between wave directions if the specified wave direction falls in between wave directions available in the WAMIT output files.
Best regards,