Peder Norrby explains how to create volumetric type smoke in After Effects using his Trapcode Particular plugin.
“This was an attempt at creating a volumetric looking smoke effect, similar to this vimeo.com/?9142476 It was totally improvised so it shows how I experiment to get the settings right. After rendering the final clip I noticed I had to change the Particle>Size over Life curve so the particles size faded out rather than just disappearing abruptly. I also setup Aux>Opacity over Life so the auxiliary particles faded out (using opacity). Final render: vimeo.com/?16224283 More info and AEP here: trapcode.com/?sharelog/?2010/?10/?27/?volumetric-smoke-with-trapcode-particular.html”