[jwstolk]

I'm generating animations, based on the interDyMFoam DTCHull example.
I wrote a tool and additional scripts to automatically stop openfoam, increase the velocity of the "tank" and then re-start openfoam for another N seconds, etc. I have the time annotation in my parafoam view, and in the generated animations.

I would like to anotate the velocity of a single point (deep in the tank, away from the ship) or the velocity anywhere in the inlet mesh, so I have the velocity listed in the animation, just like the time.
(i.e: render a single number, updated for each frame, not generate a plot)

The velocity change factor and time between changes vary a bit, so it is very difficult to track and remember the velocity of each time for every run. The velocity can't be calculated from the time.

I can't find any example on google or this forum, other than annotating the time. Is there a way to annotate the velocity at a specific point?

If necessary, I can add extra data-sets to all the time folders, with the "expected" velocity. If I could somehow annotate that value in the animation, that would be a good alternative solution.

[jherb]

Perhaps these links help:
https://paraview.uservoice.com/forum...om-annotations
http://stackoverflow.com/questions/2...python-scripts

[jwstolk]

Originally Posted by jherb

Perhaps these links help:
https://paraview.uservoice.com/forum...om-annotations
http://stackoverflow.com/questions/2...python-scripts

Thank you! Especially the last two examples in the first link look very promising. I will try it out and post what worked.

[jwstolk]

Originally Posted by jwstolk

I will try it out and post what worked.

I finally had some time to test this. It looks like the PythonAnnotation filter should do the trick.
I have installed numpy, and now I don't get errors about missing numpy any more.

I have:
Array Association: Cell data
Expression: "u=%f knots" % (max(input.CellData['U'][1,0])*0.51444*10000)

I added the 10000 factor because the results are very (too) small, but they do change with each frame in the animation.

But the actual values seem random, and I don't know how to properly select a specific cell.

I also can't find the correct way to extract the X value from a specific cell in the VTKCompositeDataArray. max() does not generate an error, but no useful value.
Does anyone know how to extract the velocity along the X-axes of a specific cell?

(or from a specific coordinate in the FieldData, that would be even better)
I only have a little python experience, but never used numpy and most examples and documentation I can find do some computation on the VTKCompositeDataArray, not extracting a single value.

[jwstolk]

Originally Posted by jwstolk

I will try it out and post what worked.

I replaced the %f with %s to show the whole VTKarray so I could see what data was there. In the end I found correct values in the inlet-patch

This works very well:

in the dataset:
enable: "interpolate volFields" and "Patch Names", then select "inlet_patch" and "U"

in the Python annotation filter:
Array Association: "Point Data"
Expression: "t=%.3f sec. v=%.3f m/s = %.1f kn" % (t_value, -max(input.PointData['U'][1,0]), max(input.PointData['U'][1,0])*-1.94384)

result: "t=45.000 sec. v=5.144 m/s = 10.0 kn"