Hello everybody;
In my research for working on wind turbines; as you know; I need outputs of WAMIT as inputs of HydroDyn but I dont have access to this WAMI software and also I don’t have the money to buy; so I wonder if anyone can give me the outputs of WAMIT for using in FAST by some inputs that I want; or any inputs which are correct and tested before!
Waiting for any replies
THANK U for the help
Dear Hamid,
NREL can provide you WAMIT input and output files for models in the public domain that we have already generated (such as the for the OC3-Hywind spar buoy), but NREL does not have the resources to develop input files and run models for your own unique design.
Best regards,
Dear Jason
Thanks for your kindly reply;
mine is not a unique design, it’s a 5MV offshore TLP of NERL and I think there wouldn’t be any problem.
should I give you my own sea condition or it could be done by NERL too?
Thanks again
Best
Dear Hamid,
You can find a complete FAST model (including WAMIT outputs) for the NREL 5-MW turbine atop the MIT/NREL TLP here: wind.nrel.gov/public/jjonkman/NR … MW_TLP.zip.
The torque and pitch controller is implemented in GH Bladed-style DLL format. This controller require FAST’s interface to GH Bladed-style DLLs, which is not a default option in FAST v7.02.00d-bjj. You can find a version of FAST with this interface here: wind.nrel.gov/public/jjonkman/FA … erface.exe. Or if you’re adventurous, you can recompile FAST yourself using the guidance from the FAST User’s Guide.
We purposely left out the wind files from these archives, because adequately sized wind files for the NREL 5-MW are typically very large. See the last four posts on the forum topic linked here for an explanation and for link to where you can download a TurbSim input file for this turbine: Updated NWTC Design Codes Available on Our Web Site.
Best regards,
Dear Jason
I am a freshman in the use of Open fast and I have encountered some problems in learning this software, So I hope to ask you some questions
The first question is that I want to know whether openfast can output stress alone, because I have searched some manuals and materials, and have not found the content of direct output stress, so I want to confirm whether openfast can not directly output stress, we can only get stress by post-processing the internal force. (And I didn 't find the stress part in the output file list on the official website.)
In addition, I also encountered some problems in the hydrodynamic file. In the platform part of the hydrodynamic file, I tried to obtain the internal force of the outer buoy of the semi-submersible foundation. However, because I did not have wamit software to help me pre-process, I could only use an example in git-hub ( the relevant code screenshot is below ) to calculate the internal force of one position of each buoy. Secondly, I learned that the current maximum value of Nbody is 9, so can I get semi _ 9body through other finite element software ? Because I want to output the internal force of the buoy along the height just like the internal force of the output tower.
Best regards
ZhichengTang
Dear @Zhicheng.Tang,
Regarding your first question, OpenFAST calculates sectional loads (forces, moments), but OpenFAST will not calculate stress directly. You could calculate stress from load via suitable post-processing, e.g., see the following forum topic for more information: fatigue calculation.
I’m not sure I understand your second question, but I’m not aware of any limitation to the number of potential-flow bodies in HydroDyn; that is, NBody can be larger than 9. Regardless, substructures where hydro-elastic effects are important are typically thin or small volume, where potential-flow is not necessary; rather, for such structures, the strip-theory formulation is likely a better approach.
Best regards,
Dear Jason
Thank you for your timely reply, I am sorry that my English expression is not accurate. My second question is that I see the Wamit file that needs to be retrieved from the hydrodynamic input file in the manual, and the manual says that the [.1 ] [.3 ] [.hst ] suffix file in the following screenshots is written through WAMIT ( as shown in Figure 1 ).
I wonder if I can get those files through some other frequency domain calculation software without WAMIT.
In addition, I have some personal understanding of the calculation of the outer buoy, I hope you can help me to correct it.
The example I found in the git-hub can only calculate the force of the buoy with the top number of 1,2,3,4 points ( as shown in Fig.2 ), and I hope to calculate the force of the buoy section at three different heights of red, green and yellow in the elevation ( as shown in Fig.3 ).
I want to know that if I want to calculate the force of multiple sections, I not only need to add Nbody coordinates in the hydrodynamic file ( as shown in Fig.4 ), but also need the corresponding WAMIT format file. Is this understanding correct ? I hope you can help me out. Thank you very much.
Best regards
ZhichengTang
Dear @Zhicheng.Tang,
From my understanding, you want to break up the central column and each offset column of the OC4-DeepCwind semisubmersible into four bodies so that you can calculate internal member-level loads at three points (red, green, yellow) each. This would require NBody = 4x4 = 16, where each body is represented in WAMIT format.
You can use any frequency-domain wave-body interaction potential-flow solver (the HydroDyn module of OpenFAST doesn’t require that you use WAMIT); regardless, WAMIT output format is required by HydroDyn.
Best regards,
Dear Jason
Thank you very much for your reply. It helped me solve my problem!
Best regards
Zhicheng Tang
