Creating space nebulas was one of the main drivers behind me wanting to study volumes more. I had a bit of a breakthrough today that led to some pretty sweet results.
The main issue I was having was getting the shape. If I'm using a particle system I can control the particles directly will all sorts of noise and force modifiers, but I couldn't do that with these volumes. I could emit them from a defined emitter, then a fluid sim happens based on some physical parameters like gravity or buoyancy. The key was that I could emit a force from another piece of geometry.
The breakthrough was realizing I could position geometry with particles then indirectly affect the fluid sim with particle dynamics.
So in the above image I have these particles which are displayed as arrows and their movement is being driven by a few turbulence fields. I then instanced a plane onto each particle so that it was aligned with the particle direction. I then made each one of those planes emit a force that moved the fluid, that way I could control the fluid with the particle fields. Once I figured that out, I can manipulate the fluid pretty much however I want.
All the images I created are actually the same fluid sim, but just from different angles or different parts of the simulation.
I added the background stars and a few other bells and whistles in post. Hope you all like! I'm one step closer to creating a grand space opera :p