How do I post-process or Set up to show 3D vortex generation?

Antang808 · October 31, 2019, 22:29

I want to show with Fluent the vortex generated from a VG in a similar fashion of NASA's simulation of an aircraft landing gear (https://www.youtube.com/watch?v=-D5N_OnZ_Tg) or this

where I only show the vortexes generated. I have a feeling it might be with numerous isosurfaces but I can't get it to work. Also does it have to be an LES solver? Does anyone know how to do it in CFD post or Fluent?

LuckyTran · November 1, 2019, 10:33

It is indeed a bunch of isosurfaces of something and they are usually colored by velocity but sometimes pressure. The isosurfaces preferably would be a vortex detection method (like Q-criterion, or Lamda-2 criterion and so on) but a very crude way is to take isosurfaces of vortcity. As crude as it might be, a lot of people, NASA included, loves doing this.

It depends on the vortex and vortex generator whether you need LES/DNS. You do need the right physics to generate the vortex. Some vortices (the classical named ones) are coherent and can be simulated with plain old URANS because they have nothing to do with turbulence. Heck, your flow might even be laminar.

It's relatively straight forward to make an isosurface in Fluent (and CFD-post) for a particular time. You should be able to do at least this much. It's like writing your name on a test. Then it's just a few more steps to auto-generate it in time.

October 31, 2019, 22:29	How do I post-process or Set up to show 3D vortex generation?	#1
Antang808 New Member Anthony Tang Join Date: Feb 2019 Posts: 7 Rep Power: 8	I want to show with Fluent the vortex generated from a VG in a similar fashion of NASA's simulation of an aircraft landing gear (https://www.youtube.com/watch?v=-D5N_OnZ_Tg) or this where I only show the vortexes generated. I have a feeling it might be with numerous isosurfaces but I can't get it to work. Also does it have to be an LES solver? Does anyone know how to do it in CFD post or Fluent?

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November 1, 2019, 10:33		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,797 Rep Power: 66	It is indeed a bunch of isosurfaces of something and they are usually colored by velocity but sometimes pressure. The isosurfaces preferably would be a vortex detection method (like Q-criterion, or Lamda-2 criterion and so on) but a very crude way is to take isosurfaces of vortcity. As crude as it might be, a lot of people, NASA included, loves doing this. It depends on the vortex and vortex generator whether you need LES/DNS. You do need the right physics to generate the vortex. Some vortices (the classical named ones) are coherent and can be simulated with plain old URANS because they have nothing to do with turbulence. Heck, your flow might even be laminar. It's relatively straight forward to make an isosurface in Fluent (and CFD-post) for a particular time. You should be able to do at least this much. It's like writing your name on a test. Then it's just a few more steps to auto-generate it in time.