Dear All,
I am trying to visualize vortices of the CFD simulation and for this purpose I use the lambda2 criterion but I faced a problem with this method: there are big vortices and a lot of small vortices. And these small vortices spoil visual quality hiding big vortices for ANY VALUE of the lambda2 ISOSURFACES. How is wise to use smoothing operators before using lambda2 criterion? When I read articles in turbulence there are nice pictures without small vortices. How they achieved it?
Are there any recipes that are not written in articles?
I am using Paraview
Best regards,
Evgenii
Have you tried to increase the lambda2 value?
On the other band, you can apply a filter procedure on your velocity field.
Evgenii,
I think the word "honest" is likely to be less relevant here. I hope those articles do explain in their methods how do they get the results they show. For this particular reason I insist in many reviews to see the data and the code used, for the sake of reproducible science.
Regarding lambda2 method or any other method - all those will identify what you define - meaning that if you filter out some sizes, it is okay if it's reported, and it will specifically filter out (as suggested Filippo Maria Denaro ) the small sizes. If you smooth the result after the selection - it's also possible, again you're requested to explain it in the paper.
If you use PIV, there is a nice package called PIVMAT and if Python, we try to develop (disclaimer - I'm one of the developers) PIVMAT's clone, called PIVPy (https://github.com/alexlib/pivpy). For CFD data I do not have recommendations.
Regards
Alex
No smoothing operators. We visualize small and big vortices but we use numerical grids of 20 million cells and normal plotting facilities.
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