Post-processing error while displaying noSlip boundary condition in Paraview (especially for patches inside MRF regions)

I came across some potential issue inside the noSlip boundary condition in terms of displaying the correct data in paraview or other post-processing programs (especially for boundary patches inside a MRF zone).

• I checked the simpleFoam tutorial named mixerVessel2D in which the patch rotor is set to a noSlip condition for U
• I copied this case named mixerVessel2DFixedValue in which I changed rotor patch in the U field to a fixedValue; uniform (0 0 0); type

Outcome:

• The cell values of both analysis are identical and hence everything is fine
• However, analyzing the patch values for the patch rotor (or field interpolated data) will result in different outcomes/visualizations
• Due to the fact of a missing value entry inside the noSlip condition, Paraview will display the internal field values -> as given in the commit Kitware Commit - Resolving OpenFOAM patches without a value field
• For any patch inside a MRF region (or even on normal walls), the displayed results will be inconsistent compared to the fixedValue condition. The reason is simple. Here we either keep the value uniform (0 0 0) or update the patch values to a nonuniform List<vector> list (e.g., for patches inside a MRF zone)

Therefore, in order to allow the user to access the correct data and visualize it, a value field for the noSlip condition should be written into the boundary condition.

If anything is not clear or one needs more information, please let me know. Tobi