Correct value of WaveTMax

Wind & Water Computer-Aided Engineering Software Tools
1

[b]Dear Sir,

What it is the optimum or correct value to be used for WaveTMax in Hydrodyn file. I have run the analysis with three different values like 630, 3600 and 5000. surprisingly the surge value changes with change in WaveTMax where as there is slight change in pitch value and no change in heave. Is there any formulae or relation that can give idea for selecting the WaveTMax value.[/b]

2

Dear Sir,

What it is the optimum or correct value to be used for WaveTMax in Hydrodyn file. I have run the analysis with three different values like 630, 3600 and 5000. surprisingly the surge value changes with change in WaveTMax where as there is slight change in pitch value and no change in heave. Is there any formulae or relation that can give idea for selecting the WaveTMax value.

3

Please do not post the same question in multiple topics. I have moved both your questions to a new topic, which someone will answer when time permits.

4

Dear Utkarsh,

WaveTMax sets the length of the incident wave kinematics time series, but it also determines the frequency step used in the inverse Fourier transform, so, changing WaveTMax between simulations will result in different wave-elevation time histories. The draft HydroDyn User’s Guide and Theory manual provides some guidance on setting WaveTMax: nwtc.nrel.gov/system/files/Hydr … nual_0.pdf.

Best regards,

5

Dear Sir,

Thank you for such a prompt reply. Since hydrodyn manual states that If WaveTMax is less than the total simulation time, HydroDyn implements
repeating wave kinematics that have a period of WaveTMax. So, Is it right to make WaveTMax equal to the Tmax in the .fst file before running simulation.

6

Dear Utkarsh,

Because HydroDyn will repeat the waves with a period of WaveTMax, for regular waves, you may set WaveTMax equal to WaveTp. For irregular waves, we recommend that WaveTMax be set to at least 1 hour (3600 s) even when the simulation time (TMax) is less, as stated in the draft HydroDyn User’s Guide and Theory Manual. If you simulation is longer than 1 hour, set WaveTMax greater than or equal to TMax.

Best regards,