Hi everyone,
I have a problem to model the tower. We simulate with OpenFAST V2.1.0 a site with a water depth of 30 m. Thereby we adapt the monopile to a diameter of 7 m. In a height of 10 m above still water level (SWL) is the transition piece (TP) with a height of 10 m. The diameter of the TP tapers from 7 to 6.5 m. The TP is to be modeled as part of the tower,which starts at 20 m above SWL up to a height of 87.5 m above SWL.
Modeling the monopile is no problem. For the tower I adjusted the values in the ElastoDyn-Tower-File TwrFile and in the AeroDyn15 file the table “Tower Influence and Aerodynamics”. But the visualization in Paraview still shows an offset between the monopile and the tower.
Did I miss a setting for the diameter of the tower?
Best regards,
Malte Frieling
Dear Malte,
It sounds like you’ve specified the tower properly in ElastoDyn. The issue you’ve identified is a limitation of the surface visualization feature of OpenFAST. The surface visualization of the tower is based on the ElastoDyn inputs TowerHt and TowerBsHt, but because the tower diameter is not actually specified in ElastoDyn, the visualization assumes a given tower diameter and linear taper. This is mentioned in Table 4 of the FAST v8 ReadMe file, where the surface visualization features are summarized: drive.google.com/file/d/17LDwMn … sp=sharing.
Best regards,
Hi Jason,
I have successfully simulated the OC3 Hywind FOWT using hydrodynamic data from AQWA. I simulated regular wave condition with results matching from a paper. However, when I attempt to view the model in paraview, only the wind turbine can be seen with no substructure. I removed the member and joints information from the Hydrodyn input file as suggested in readthedocs as I used potential flow model so I am wondering what I am missing for platform visualization.
I have attached paraview image.
Kind regards,
Josh
Dear Josh,
This is simply a limitation of the visualization functionality of OpenFAST. As documented in the FAST v8 ReadMe file, the surface visualizations for the offshore substructure are based on the strip-theory (Morison) members and joints, and so, are not visualized if you do not have strip-theory members. You’ll have to customize the visualization source code if you wish to visualize the substructure in some way for a model without strip-theory members.
Best regards,
Hi Jason,
Ah I see, thank you for explaining.
Kind regards,
Josh
Dear Dr. Jonkman,
I encountered the same problem as posted before. After checking your reply, and I got to know that this is a limitation for the members without adopting the strip theory. Could you give me some more tips regarding how to compile the source code if possible? I checked the problem posted on Github (github.com/OpenFAST/openfast/issues/539). I realized the foundation visualization has been solved, right? Another alternative solution might visualization in ADAMS, but it seems the interface to ADAMS has changed from the version. Any suggestion would be appreciated. Thank you
Best regards,
Jian
Dear Jian,
I’m not exactly sure what problem you are referring to, but I’m not aware of recent commits into OpenFAST that improve the visualization functionality. Issue 539 was identified as “help wanted”, and not closed with a code improvement, although I provided some guidance there on what such improvements could look like.
Guidance for compiling OpenFAST is provided in the online documentation: openfast.readthedocs.io/en/main … index.html.
Best regards,
Dear Dr.Jonkman,
Sorry for the unclear explanation. I run the jacket model with FAST.V8 and newly developed OpenFAST with the samples downloaded from the r-test folder on Github. The visualization parameters are setting the same, as follow: WrVTK=2, VTK_type=1, VTK_fields=true, VTK_fps=20. However, I found different VTK files for HD, of which the files in OpenFAST are “_Morison.txx.vtp”, while the ones in FAST.V8 are “_MorisonDistrb.txx.vtp” and “_MorisonSurface.txx.vtp”. I might miss something in the Hydro.dat file when employing OpenFast, could you give me some tips. The corresponding figures in the Paraview are also attached.
Besides, I want to know that the data array “force”, “moment”, “orientation”, “translational velocity and acceleration”, and “rotational velocity and acceleration” refer to x/y/z axis or something else. It might be a simple problem and thank you for your consideration.
Best regards,
Jian
Dear Jian,
For the OpenFAST model, are you using OpenFAST v2.6 or newer? In the recent upgrade to OpenFAST for modeling floating substructure flexibility and member-level loads (pull request github.com/OpenFAST/openfast/pull/537, released in OpenFAST v2.6), the strip-theory (Morison) implementation was changed from using distinct point and line2 meshes to only using point meshes. While the new functionality is very powerful, this change had the unfortunate effect of losing the ability to visualize the Morison members from the line2 mesh. Again, future work is needed to improve the visualization functionality of OpenFAST, particularly for offshore support structures.
Regarding the mesh fields you are referring to (force, moment, orientation, velocity, acceleration), these are all vectors expressed in the global inertial frame X/Y/Z coordinate system.
Best regards,
Dear Dr. Jonkman,
Yes, I employed the OpenFAST 2.6.0 and I will change to version 2.5.0 to see the difference. Thank you for your explanation, and I am glad to hear the new function of modeling floating substructure flexibility and member-level loads.
Besides, I still have the problem with the moment visualization refer to the fixed axis in the Paraview. If I want to know the x-moment, how could I choose the options (It seems only the “moment” option could be chosen)? The menu in Paraview is shown below. 
Furthermore, I tried to depict the moment in the blade, and the maximum one exists in the middle-span rather than blade root. I want to confirm the result is whether appropriate, and I guess it is might be caused by the pitch control, right?
Many thanks.
Best regards,
Jian
Dear Jian,
Regarding the moment visualization in ParaView, this is more of a ParaView question than an OpenFAST question. I’ve seen users plot vectors as arrows by adding glyphs, but I cannot provide guidance on that myself, because I’m not experienced with that myself.
The moment you are visualizing is not the reaction moment within the blade, which is not a standard visualization output from OpenFAST. You haven’t stated from which mesh the moment comes from, but I would guess you are plotting the moment from the AD_Blade mesh, which is the applied aerodynamic moment rather than the reaction moment within the blade.
Best regards,
Dear Dr. Jonkman,
Sorry for the late response, and thank you for your reply.
Best regards,
Jian
I’ve now raised the inability of OpenFAST v2.6 to visualize offshore support structures in the following OpenFAST github issue: github.com/OpenFAST/openfast/issues/776.
