FASTV8-HydroDyn-Wavemod4

Wind & Water Structural Analysis
1

Dear Dr.Jason

Thanks for reading my message.
I have some problems with the wavemod4. Here is my question:
I’m trying to consider the modifed Jonswap spectrum in shallow water depth. So i need to multiply the Jonswap spectrum with the TMA factors to consider the shallow water effect. Fisrtly, I just multiply the original Jonswap spectrum with the TMA factors in Hydrodyn source code(waves.f90), and it failed. Is there any exmaple for the use of wavemod4? In your reference mannual, it said that the user-difined spectrum can modifie the waves.f90 source code. Can we redifine other parameters in the source code?
If wavemod4 didn’t work, can we use the inverse Fourier transform to transform the modifed spectrum into time-domin in MATLAB,and then input it into the FAST(use wavemode5)?

Thanks very much! I am looking forward to your reply.

Best regards
Lixian Zhang

2

Dear Lixian,

What do you mean when you say that you modified Waves.f90 and “it failed”? To use WaveMod=4, all you should need to change is how WaveS1Sdd is set in SUBROUTINE Waves.f90/UserWaveSpctrm(). The sample UserWaveSpctrm() SUBROUTINE provided in FAST v8 simply sets WaveS1Sdd = 0.

Being open source, you can, of course, change the FAST source any way you want.

If you already have a wave-elevation time series that you want to use within FAST, then you can also use the WaveMod=5 option.

Best regards,

3

Dear Dr. Jason

Thanks for your reply!

Best regards
Lixian Zhang