Visualizing Offshore Support Structures

[jjonkman]

Is your feature request related to a problem? Please describe.
In the recent upgrade to OpenFAST for modeling floating substructure flexibility and member-level loads (pull request #537, released in OpenFAST v2.6), the strip-theory (Morison) implementation of HydroDyn 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. And SubDyn has not supported visualization of members because of its use of point meshes. (Currently in OpenFAST, the surface and line visualizations in OpenFAST's visualization functionality rely on the use of line2 mesh data structures.) So, in OpenFAST v2.6, it is not possible using the visualization functionality of OpenFAST to visualize offshore substructures without modification of the OpenFAST source code or by manually adding it within the visualization post-processor (e.g., adding a glyph in ParaView).

Describe the solution you'd like
Add functionality to visualize members in HydroDyn and SubDyn based on their inherent point meshes.

Additional context
Neither is it currently possible to visualize the mooring lines in floating wind applications, per issue #539.

[robytian]

So, it's currently impossible to visualize floating platforms and mooring lines without modifying the source code, right?

[jjonkman]

Hi @robytian,

Yes, that is correct. In OpenFAST v2.5 and older, it was possible to visualize the floating platform (through Morison members), but this functionality was lost in v2.6 and newer. OpenFAST has never had the ability to visualize the moorings. Both of these issues will require a source code change to resolve.

Best regards,

[jjonkman]

Neither is it possible to visualize a floating platform in OpenFAST that is hydrodynamicly modeled with potential-flow theory, based on the WAMIT (or the like) mesh.

[shawnmeng9]

My name is Shawn Meng, and I am a software engineer at Bentley Systems in Canada. I have developed a program of visualizing OpenFAST wind turbine geometries including the offshore support structures based on the OpenFAST inputs. Here is a short video to show how it works. I plan to make all of the code used in this program open-source and contribute to the OpenFAST community. Please let me know if you have any questions about this and would like to have further discussions.

If you are interested in this program, you can download it from my GitHub page (https://github.com/shawnmeng9/ConvertFast/releases) or email me at [email protected]. Thanks!

visualization-of-openfast-geometries.mp4

[jjonkman]

Note: While the issue mentioned above has not yet been fixed, it should be noted that the issue mentioned above is related to surface and stick-figure visualization of the offshore support structure.

Without changes to the source code, it actually is possible right now to visualize the offshore support structure as a "point cloud". By selecting VTK_type = 3, information about all of the meshes used by the inputs and outputs of all OpenFAST modules are written to the VTK files. These include, the mesh associated with the structural nodes in SubDyn, the mesh associated with the hydrodynamic nodes in HydroDyn, and the mesh associated with the fairleads in the mooring modules (like MoorDyn). You should be able to visualize these mesh nodes as points or other graphics in ParaView.

Best regards,

[andrew-platt]

This issue has been partially addressed in #1768 and will be released in v 3.5.1. HydroDyn and MoorDyn meshes are now easy to render. The SubDyn mesh has not been addressed.

[RBergua]

I'm using OpenFAST dev (commit 4fafe68) and I confirm that I can visualize the mooring lines from MoorDyn and the Morison elements from HydroDyn. Yay!

However, I'm facing a problem in MoorDyn. In reality, the buoyant cans observed in the above screenshot should be defined in MoorDyn. I just defined them in HydroDyn for visualization purposes.

The problem is that when I try to obtain the visualization of those cans (rods in MoorDyn), OpenFAST crashes:

The definition of the cans in MoorDyn is as follows:

Is there an easy fix or work around to visualize those cans?

[andrew-platt]

There isn't a super easy fix for visualizing the cans, but it wouldn't take too long to do -- we ran out of funding before that part was completed when we added the lines. If there are funds available, it would probably take me about 5 hours to complete, test, and do a PR.