Fragmented Q criterion results

Hello everyone,

When I use ParaView to extract iso-surfaces of the Q criterion, the extracted results always appear very fragmented. Due to my lack of experience, I have no idea if this is normal.

I’m using ParaView 5.11.1 to process high-order VTU files generated by the PyFR solver. Sometimes, it crashes without warning, but that’s a separate issue we don’t need to discuss here.

At first glance, the iso-surfaces of the Q criterion seem okay, but when zoomed in, they appear highly fragmented. Please refer to the first two images.


I’ve taken the liberty of using another Q criterion image from elsewhere for comparison. The last image looks excellent, with a very smooth transition, which is quite different from my results. Is there an issue with how I’m processing the data? Are there any methods to make the results appear smoother?

I’d greatly appreciate any advice.
Beat regards.