a) Now we need something to burn, fire coming out of a bunch of doughnuts just doesn't make sense. I'll be using some simple logs I modeled in about 20 minutes, you can either import them or make your own.
b) Stick the logs into your fireplace, making sure they are not too close to any edge of the box. Because we used spherical edge dropoff there won't be any fire around the borders(it just fades to invisible).

c) You need to position the emitters now, make sure to place them where fire should be coming from. Some of the places I make sure to stick one is where two logs touch, along the bottom of any log that isn't flat on the stone, around the edges of the log ends(where it would be coming out from under the bark), and in the middle of the pile of logs(these can just float, we won't ever see in there). Also, try not to spread them too uniformly, clump them up a little.

d) You may or may not have a good number of emitters. If you need to add more, don't just duplicate one that you have already. A normal copy won't be connected to the fluid, so it'll be useless; and if you turn on Duplicate Input Graph it'll duplicate the fluid as well, which is bad 'cuz now your computer is doing twice as much(and caching will very quickly fill your hard drive with a cache for each fluid)
NOTE: Moving the emitters will invalidate your cache, but maya won't warn you. So before doing anything else, especially saving, delete the cache.

a) I usually don't have time to do this all the way through, and it is generally unnecessary anyway. If you need to get close up to the fire though, you'll want to add collision detection. This adds a lot of time to caching, and therefore saving and rendering.
b) Make sure that both the Initial State and the Cache have been deleted, they won't work anymore.
c) Reposition the emitters so that none is actually touching the surface.
d) Collisions depend heavily on resolution, the higher the better. You may want to raise the resolution of the fluid and even smooth the log models.
e) Select the logs and the fluid, Fluid Effects>Make Collide.
f) If you are getting that close, you'll also need to add some heat shimmer to the shot. This would best be done in compositing, as it would require another whole dynamic simulation in maya(particles or fluids).

a) Earlier I mentioned that we had a way around having to play through the mushroom cloud at the beginning of the sim. This is it. Initial States are a one frame cache that define the first frame of the sim. This is the only way two caches can be hooked up to one fluid at the same time.
b) Play through the sim, past the weird part at the beginning, and hit stop (somewhere around frame 50).
c) Select the fluid, Fluid Effects>Set Initial State
d) Hit the rewind button to go to the first frame, notice that nothing about the fluid changes.

NOTE: If you have animated attributes, which we do, you need to be careful about where you cut this. If an attribute has changed greatly since the first frame (say from 10 to 1) and you create the initial state, you'll get a jump from 1 on the first frame to 10 on the second. In this tutorial our animation doesn't happen 'till about 100 frames in so we don't have to worry about it.

e) now you can create a cache. just to let you know, you can create an initial state after the cache. It'll just cut off the front end of the cache, giving you a shorter animation. If you need to get that time back, you can use Fluid Effects>Append to Cache. I try to avoid this whenever possible as it wastes a lot of time.

 

a) Now's a good time to see where we're at. Set up the Render Globals (image name, numbering, etc). Save the file, kick off a batch render: Render>Batch Render.