The purple shows where all the gas and yes gas not liquid should go. It must collide and be held in by a couple moving parts. The first thing I tried was to use a particle system. The collision stuff was waaaay too bouncy so I tried to use a follow curve forcefield. And after getting frustrated with that I tried using a smoke sim and smoke colliders and the air would not even go into the top. The inside and outside mesh are one in the same if that matters. And if so should I attempt to separate the two?
So I gave up and was going to manually edit a bunch of frames in GIMP but that was waaaay too much. So now I am here after many hours.
Would it be best to use a fluid sim and forcefields? Or is blender just not the software for that kind of thing?