[stridder]

Good morning,

I'm looking for a nice looking/'impressive' way to visualise 3D fluid development past an obstacle from 3D sumilation done using time-dependent Navier-Stokes. I am more or less familiar with paraview only.
I've seen nice looking plots using Q-criterion, but never used it myself. What data (velocity vectors? or velocity gradients etc?) do I need to do Q-criterion plot?
Is there a another way to visualize in 3D?
Reynolds number is up to 100.
Thank you very much.

[flotus1]

Isosurfaces of the Q-criterium always "look nice", especially when colored with the flow velocity.
Same thing applies to the vorticity magnitude (if there is enough vorticity in the flow of course).
There is more than one way to do this in ParaView. One of them starts with a fluid velocity vector result. Apply the filter "gradient of unstructured dataset" on this result. In the properties panel of this filter, you can choose to compute vorticity an Q-criterion. Then apply a "contour" filter and choose a suitable iso-value. You will have to play around a bit with the value. Color the iso-surface e.g. with the velocity magnitude and animate.

720p_iso_vorticity.0050.png

720p_iso_vorticity.0100.png

720p_iso_vorticity.0300.jpg

720p_iso_vorticity.0600.jpg

720p_iso_vorticity.0900.jpg