fluid pyro volume animation

[meeotch]

Is it possible to animate the size/position of a fluid volume during a sim? The context: I've got a long, skinny, quickly-sideways-moving object that's emitting fluid (pyro). The resolution of the pyro volume needs to be really high in order to capture the detail of the skinny emitter, otherwise emission is just a big blob. The volume also needs to be really large because the object is swinging around quickly, and covers a lot of ground. (Imagine putting a pyro volume around that chubby youtube kid's lightsaber, and you'll get the idea.) Obviously, this isn't a great combination for my sim times or my sanity.

However, the flames burn out quickly, so the volume is about 90% empty at any given time. Is there any way to constrain the solver to the area immediately around the object as it moves? Alternatively, is the pyro solver "smart" enough to optimize empty voxels (when boundaries are off), so that a large, sparse volume is not wildly inefficient?

[Macha]

Kind of. You can use a gasresize node (i think its called like that, its in the shelf tools). You can then animate a box by hand or do it more procedurally by using the bounding volume of your fluid. The procedural solution is soso, and I never found a really stable way of doing it (it fails with an upres setup for example). There is a setup for this here:

I think there is some internal optimization for sparse volumes, but I'm not sure. I dimly remember reading something like that somewhere.

edit: You can customize the setup in that example by referring to certain fields only, heat or density, whatever the case may be, or give it a minimum and maximum size. It will however always be a boxshape.

Edited October 19, 2010 by Macha