Using Maya 2012 Fluids. Fluids was emitted from Fluid Emitters that were attached to a set of plane objects under a row of Drain geometry which was built as a collision object, in order to breakup fluids from being too uniform. High swirl value, low turbulence and Damping setup. Shape of smoke was controled by graphs in the Opacity channel.  Fluids's density  was Keyframed and cycle animated to randomize the look of smoke.Used Texture Map to emit density by mapping animating Noise's texture time onto Density Emission Map to get variety smoke shapes.

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Self shadow lighting. Rendered using Mental Ray at Final Resolution of 350, Depth levels separated layers and composited in Nuke.