hello,everyone

I have some doubt when I’m reading the HD manual,But I don’t know whether my understanding is right.So hope someone can help me.

This is my opinion :In HD input file 2ND-ORDER WAVES section is only used in strip-theory. IF we set WvDiffQTF and WvSumQTF to TRUE,we can generate the 1st plus 2nd order waves,we can get the second-order contribution in the strip-theory. As for the potential-flow theory, we do not use the section,we can get the second-order contribution(such as mean drift and slow dirft) by the 1st order waves spectrum(diff-freq and sum-freq).

Hope someone can tell me whether I am correct.

Best Regard

Ruiliang.Wang

Dear Ruiliang,

Correct. Inputs WvDiffQTF and QvSumQTF in the HydroDyn input file only apply to the wave kinematics used by the strip-theory solution, The second-order potential-flow solution is enabled by the inputs in the “second-order floating platform forces” sections of the HydroDyn input file. Inputs WvLowCOffD, WvHiCOffD, WvLowCOffS, and WvHiCOffS apply both to the second-order strip-theory solution and the second-order potential-flow solution.

Best regards,

Dear Jason,

Thanks for your reply in time.

If we set Inputs WvDiffQTF and WvSumQTF to false, Is the rest four variables(WvLowCOffD, WvHiCOffD, WvLowCOffS, and WvHiCOffS) still useful for strip-theory and potential-flow theory.

My Opinion: If set false ,we can not use the last four variables in strip-theory, we can only use the 1st order waves in the strip-theory,there is no 2nd-order contribution. As for the potential-flow theory,no matter how we set the WvDiffQTF and WvSumQTF, the four variables(WvLowCOffD, WvHiCOffD, WvLowCOffS, and WvHiCOffS) can be used if we set enable in second-order floating platform forces section.

Is it correct？

```
Best Regards
Ruiliang.Wang
```