How to output the wave height at a specified location.

[banzhiqing]

Dear Professor,

I have encountered an input option in the file named IEA-15-240-RWT-UMaineSemi_HydroDyn.dat, which refers to "the number of points where the incident wave elevations can be computed." May I inquire if this option enables the output of wave elevations at user-specified locations? For instance, could it provide wave elevation data at a fixed point 10 meters in front of the wind turbine (at coordinates x = -10, y = 0)? If it is possible to output wave elevations at a specified location, what would be the procedure to configure it? Your guidance on this matter would be greatly appreciated.

Best regards

[jjonkman]

Dear @banzhiqing,

Yes, that is correct. Specify NWaveElev to the number of points (up to 9) that you want the wave elevations output at and specify the (X,Y) locations of those points in the list of WaveElevxi and WaveElevyi. Then output the wave elevation at those points by listing them in the HydroDyn OutList, i.e., Wave1Elev for point 1, Wave2Elev for point 2, etc. up to NWaveElev. If all you want to do is output the wave elevation at (-10,0) m, keep everything as you have except set WaveElevxi = -10 m, in which case Wave1Elev would be the wave elevation at this point.

Best regards,

[banzhiqing]

Dear @banzhiqing,

Yes, that is correct. Specify to the number of points (up to 9) that you want the wave elevations output at and specify the (X,Y) locations of those points in the list of and . Then output the wave elevation at those points by listing them in the HydroDyn , i.e., for point 1, for point 2, etc. up to . If all you want to do is output the wave elevation at (-10,0) m, keep everything as you have except set = -10 m, in which case would be the wave elevation at this point.NWaveElev``WaveElevxi``WaveElevyi``OutList``Wave1Elev``Wave2Elev``NWaveElev``WaveElevxi``Wave1Elev

Best regards,

Dear @jjonkman,

Thank you very much for your assistance, I now understand how to set these parameters.

Best regards,

[banzhiqing]

Dear @banzhiqing,

Yes, that is correct. Specify NWaveElev to the number of points (up to 9) that you want the wave elevations output at and specify the (X,Y) locations of those points in the list of WaveElevxi and WaveElevyi. Then output the wave elevation at those points by listing them in the HydroDyn OutList, i.e., Wave1Elev for point 1, Wave2Elev for point 2, etc. up to NWaveElev. If all you want to do is output the wave elevation at (-10,0) m, keep everything as you have except set WaveElevxi = -10 m, in which case Wave1Elev would be the wave elevation at this point.

Best regards,

Dear @jjonkman,

I would like to ask a question regarding the use of the JONSWAP spectrum for wave generation. How many frequencies (or phases) are there in total within the range [WvLowCOff, WvHiCOff]? Additionally, if I wish to modify this quantity, where can I make the adjustment?

Best regards,

[jjonkman]

Dear @banzhiqing,

The frequency step used by HydroDyn is related to WaveTMax, that is, WaveDf = 1/WaveTMax in Hz, or WaveDomega = 2*pi/WaveTMax in rad/s.

Best regards,

[banzhiqing]

Dear @banzhiqing,

The frequency step used by HydroDyn is related to WaveTMax, that is, WaveDf = 1/WaveTMax in Hz, or WaveDomega = 2*pi/WaveTMax in rad/s.

Best regards,

Dear @jjonkman,

Thank you very much for your help! I now understand this parameter.

Best regards,

[banzhiqing]

Dear @banzhiqing,

The frequency step used by HydroDyn is related to WaveTMax, that is, WaveDf = 1/WaveTMax in Hz, or WaveDomega = 2*pi/WaveTMax in rad/s.

Best regards,

Dear @jjonkman,

I would like to kindly seek your guidance on a question. In the HydroDyn.dat file you provided, the default value for WaveTMax is 850 s. When simulating the motion response of a floating offshore wind turbine (FOWT) under the combined effects of random wind and waves for a total duration of 6000 s (as indicated by TMax in the .fst file), should WaveTMax be set to a value greater than 850 s, or is WaveTMax = 850 s already considered sufficient for representing irregular waves? Could you please advise on the appropriate settings for TMax and WaveTMax in this context?

Best regards,

[jjonkman]

Dear @banzhiqing,

When modeling irregular sea states (WaveMod = 2), our HydroDyn modeling guidance (https://openfast.readthedocs.io/en/main/source/user/hydrodyn/modeling_considerations.html#waves) recommends setting WaveTMax = 3600 s, even when TMax is less than 1-hour. I was not the one to make the IEA-15-240-RWT-UMaineSemi_HydroDyn.dat example, but I don't see that this guidance was followed. But if you are running simulations longer than 1 hour, you could increase WaveTMax to TMax to ensure that the irregular waves don't repeat within the simulation.

Best regards,

[banzhiqing]

Dear @banzhiqing,

When modeling irregular sea states (WaveMod = 2), our HydroDyn modeling guidance (https://openfast.readthedocs.io/en/main/source/user/hydrodyn/modeling_considerations.html#waves) recommends setting WaveTMax = 3600 s, even when TMax is less than 1-hour. I was not the one to make the IEA-15-240-RWT-UMaineSemi_HydroDyn.dat example, but I don't see that this guidance was followed. But if you are running simulations longer than 1 hour, you could increase WaveTMax to TMax to ensure that the irregular waves don't repeat within the simulation.

Best regards,

Dear @jjonkman,

Thank you very much for your assistance, I now understand how to set these parameters.

Best regards,