Export data from COMSOL via VTK; Unable to see the streamlines


I want to see the streamlines in Paravie using COMSOL data. I export data as VTK (please see attached files). The streamlines look fine in my COMSOL sample file but I can not see the streamlines in Paraview after I load data in Paraview. The tracer filter is greyed out.

Velocity or temperature contours are working properly tho on a 2D plane.
I appreciate any tips.

Please share your data (ki.vtu)

I am not able to share data as it is confidential.

You may want to reach out to Kitware to set up a NDA then: https://www.kitware.com/

I am afraid that it is not an option for now.
Are you aware of a specific data format that ParaView needs to process data?
Or any other tips that I could check on my end?

To utilize the Stream Tracer filter, it is necessary to construct a velocity vector. This can be accomplished by employing the Merge Vector Components filter to combine the three component variables of velocity present in the data.

Thank you for your response.
I considered the Merge Vector Components filter and the stream tracer is now visible.
However, I don’t find the streamlines correct. In fact, I want to select my 6 inlets and then see how the streamlines would be inside the fluid domain. Not sure what I see as streamlines right now and how to increase the number of streamlines (not length)

Is there a way to select a specific surface or surfaces and see how the streamlines would evolve from there?

Thank you for your time.

To create streamlines from a specific location, you typically use the Stream Tracer With Custom Source filter. (See link below:
16. Targeted: Computational Fluid Dynamics — ParaView Documentation 5.12.0 documentation)

Since actual data is lacking, I cannot provide a more precise method, but a typical approach involves the following steps:

  1. Select nodes at the inlet. Refer to the link below for instructions on how to make the selection: 6. Selecting Data — ParaView Documentation 5.12.0 documentation
  2. Convert the selected nodes into data objects using the Extract Selection filter.
  3. Apply the Stream Tracer With Custom Source filter.

Thank you for your input.

Are aware of this? Which reader should I use and why?

I am not sure what data format you are using, but it is most likely not supported by ParaView. You need to provide a file format that ParaView supports.

It is .dat file.

Check the file format of the .dat file. If ParaView does not support this file format, it will be unable to read it.