In A Twist: The Black Art Of Vortices
Aerodynamicists mostly deal with linear or turbulent airflows around moving objects. But at some conditions and with some shapes, stable rotational flows—vortices—can occur. They can be powerful lift-generators in circumstances where linear flows alone would break down—but beware; when a vortex shows the cloven hoof, the results can be dramatically undesirable.
Read Bill Sweetman's article about the Aerodynamic Modification Kit being considered as part of future improvement packages for the Eurofighter Typhoon.