ABSTRACT
The first visual fluid phenomena we will consider is smoke, loosely following the standard reference papers by Foster and Metaxas [FM97] and by Fedkiw et al. [FSJ01], with some additional capabilities added. Our fluid in this case is the air in which the smoke particles are suspended. To model the most important effects of smoke, we need two extra fluid variables: the temperature T of the air and the concentration s of smoke particles—what we actually can see. Similar phenomena, such as vapor, can be modeled in much the same way. Generally we'll try to keep to SI units of Kelvin for temperature and keep s as a volume concentration, perhaps expressed in parts-per-million (ppm): depending on how much physics the smoke rendering is simulating, you even might need to track the concentration of different ranges of soot particle sizes separately, but we will not go that far.
