QCriterion in Paraview
 

Hi, I'm working on a turbulent duct flow.
I used Gradient of Unstructured Data set filter on velocity vector then I checked the Compute QCriterion option and Compute Vorticity
option. (as you can see below)


https://i.imgur.com/CiXu8qa.png

Finally, I used Contour to visualize the QCriterion. (as you can see)


https://i.imgur.com/dJyrMt9.png

The result can be seen in the following image ,but I think it's not correct.
Where is the problem? Did I follow wrong procedures?


https://i.imgur.com/M2b92Me.png

Sounds like the workflow I usually use to visualise the Q-criterion. What makes you think that the result you got is incorrect? I see nothing inherently wrong with it.

The procedure is correct.
Th visualize the vortices, you have to set a threshold and use a value bigger than 0.5.
For the value, obviusoly, you can decide to use a different value. 0.5 is what I commonly use.

Cheers,
Carlo