Painting fluids

One important aspect of controlling a fluid simulation (if not the most important one) is to create the right emitter setup.

You can think of the emitter as a brush used to paint in a pixel image. In fact, the container works pretty much like a 3D pixel image. You paint into one or more of the fluid channels (similar to painting into the RGB and/or A channels of an image) using emitters.

The fluid simulation will then add velocities that let your "paint" flow, curl and/or expand. But, and that's the point here, essentially the result will be what you painted at the source. You'll want to try various settings for the emitter texture scale, octaves and contrast. Maybe use several small objects instead of one big one, use particles, animate the intensity of the emission, etc.

You can start by using only the temperature channel (disable the others) and see what different effects you can get just by varying the emission pattern and animation. You may not even need more than one channel for an effect - even in a high quality production.