The Kaufmann vortex, also known as the Scully model, is a mathematical model for a vortex taking account of viscosity. It uses an algebraic velocity profile.
Kaufmann and Scully's model for the velocity in the Θ direction is:
The model was suggested by Scully and Sullivan in 1972 at Massachusetts Institute of Technology, and earlier by W. Kaufmann in 1962.
References
Kaufmann (Scully) vortex Wikipedia(Text) CC BY-SA