Fluid Mapping Channel Render Pass ?

[NormanStansfield]

Try to use krakatoa and stoke. Soke or Krakatoa Prt fume objects gets fluid mapping into TexCoords and then you can try to extract the data further, or do whatever you want with magma modifiers. But Krakatoa and stoke are expensive and quite hard to learn. But worth of particle freedom it offers.
hope this helps