 It was named after the Austrian physicist, mathematician, and poet Josef Stefan for his early work on calculating evaporation rates.The Stefan flow is distinct from diffusion as described by Fick's law, but diffusion almost always also occurs in multi-species systems that are experiencing the Stefan flow.In systems undergoing one of the species addition or removal processes mentioned previously, the addition or removal generates a mean flow in the flowing fluid as the fluid next to the interface is displaced by the production or removal of additional fluid by the processes occurring at the interface.