Use of 2ND-ORDER WAVES section in HD input file

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Ruiliang.Wang
Posts: 80
Joined: Sun Nov 24, 2013 6:21 pm
Organization: YANSHAN UNIVERSITY
Location: China

Use of 2ND-ORDER WAVES section in HD input file

Postby Ruiliang.Wang » Wed Dec 06, 2017 8:33 am

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

Jason.Jonkman
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Re: Use of 2ND-ORDER WAVES section in HD input file

Postby Jason.Jonkman » Wed Dec 06, 2017 11:20 am

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,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Ruiliang.Wang
Posts: 80
Joined: Sun Nov 24, 2013 6:21 pm
Organization: YANSHAN UNIVERSITY
Location: China

Re: Use of 2ND-ORDER WAVES section in HD input file

Postby Ruiliang.Wang » Wed Dec 06, 2017 10:03 pm

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

Jason.Jonkman
Posts: 3730
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Use of 2ND-ORDER WAVES section in HD input file

Postby Jason.Jonkman » Thu Dec 07, 2017 6:28 am

Dear Ruiliang,

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?

Yes, that is correct.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov


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