Need help building a vortices simulation in Blender

(André) #1

Hi guys, I’m looking for someone who can help me with the following problem. Together with two other students we want to simulate colliding vortex rings in Blender. The special thing about it, however, is that the rings don’t just swirl during the collision, but new smaller rings are created. With this we want to recreate the experiment of Dr. TT Lim from 1992 (they did it in real in water as you can see here:
Does anyone have an idea how we can best simulate these rings, which of the Blender systems is suitable (e.g. smoke simulation, fluid simulation, physics system or others), whether there is a suitable plugin etc.?

We are thankful for every help and every idea.

Maybe someone has already built something like this himself and can help us directly, that would be really great.

(omgold) #2

I’d say that problem is way too dependent on simulating fluid physically accurate for the builtin sims in Blender. Note that these are mostly built to make things look realistic.

If you just want to visualize it, you could fake it, likely without doing any simulation at all (just with manual animation). Otherwise you need a real CFD software (there should be quite a few free ones around).

(RCWebmistress) #3

Thanks for giving some input. I had hoped maybe the sims in Blender (or maybe some add on) might do the trick. My original thoughts on “how” were related to the idea of rendering out an animation of this in TGA sequence and then using each image (of each frame) to find the splash that looked good.

What does CFD stand for in this case. Note that I am on Linux so I can only hope that this kind of thing is available for my setup.

(omgold) #4

CFD simply stands for Computational Fluid Dynamics. As it is a big thingie in engineering, there are plenty of software packages out there, both free and open source and commercial. And as compute clusters almost exclusively run un Linux, you don’t have to worry about finding something running there.

But honestly, if you just want a still image, I would just fake it. Model the rings and render it with volume shaders. Add turbulence effects with procedural textures. Maybe you can take a cloud tutoral like this one as a starting point:

(André) #5

Thank you very much for the answers. It’s actually about having the simulation as a video. We built the same experimental setup in real and wanted to compare both.
It’s a shame that Blender doesn’t seem to make it possible to recreate this as realistically as possible.
So now it’s up to us to familiarize ourselves with the CFD software.

(RCWebmistress) #6

Thanks so much for elaborating. I will see what comes up for CFD and see what kind of imagery it offers me as far as realism. By “faking it”, are you recommending using something more or less 2D? From the Shutterstock image, it seems like it could have been made by 2D, just as likely as my guess that I could do this in 3D (through Blender). I am looking for realism, so would be curious about the idea of this cloud tutorial (“Model the rings and render it with volume shaders. Add turbulence effects with procedural textures…”

(omgold) #7

By faking it, I mean to model it by hand in Blender. Create geometry at a reasonable detail level and render it with volume shaders (needs probably both, Volume Scatter and Volume Absorption). Details like the finer turbulence can be added then with procedural textures for the density value of the shaders.

It is a fully 3D thing, then. Nothing 2D about that. Maybe you really should watch the linked clouds tutorial. Everything I’m talking about is explained there.