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 think I might have solved this problem, but it happened about 8 months ago, so I’ve forgotten many of the details.
I’ve tried to recall, and for my VTU file, it seems that just executing the CleanToGrid command once made everything better. Next, I just needed to compute the Gradient Q Criterion and then display it using Contour, and it looked fine.
Again, it’s been a while, and I’ve forgotten whether I modified the VTU file after I asked this question. Obviously, the correctness of the input VTU file is very important. With a correct VTU file, using the method I described above, at least my problem was solved.
By the way, the latest version of Tecplot 360 also offers support for high-order curved grids, which works quite well, and you might want to try using Tecplot 360.
