Learning Forum

[javier.medina.galera]

Hi,

I would like to perform a time history analisys of a floating wind turbine by using a white noise. I have tried to use the 'User defined spectrum option with a constant spectral ordinate of 1.875 m^2/Hz between 0.05 and 0.2 Hz but I would like to know if this is the best approach or if instead I should import a wave elevation time history whose spectrum is the target white noise. What do you think? How do you usually do it?

Thank you very much!!!!

[Yu Bi]

Hi, for white noise, it would be better to use the User Defined Spectrum option with the defined frequencies from a very low frequency to a high frequency under which the structure still has a response. 

[javier.medina.galera]

Thank you very much! 
By the way, is there any way to enter a time series of waves with a duration of less than 7200s in AQWA or any of its programmes?

[Yu Bi]

Hi, Aqwa allows entering a time history of wave elevation that has a duration of less than 7200s.

[javier.medina.galera]

When I try to import a *.wht file from a wave generated in matlab and run the analysis, the duration is automatically extended to 7200s despite the duration indicated in the analysis settings, is there any way to change that??

Thank you very much!

[Yu Bi]

Hi, in order to give sufficient resolution of low-frequency resonant responses, the program requires a 2-hour duration. You can give less than 7200s wave elevation history, however, as you observed, Aqwa will extend the imported wave elevation time history to 7200 seconds by an approach which is elaborated in Aqwa Theory Manual  Section 2.1.2.3.