Vortical means pertaining to a vortex or to vortices. In fluid dynamics, the movement of a fluid can be said to be vortical if the fluid moves around in a circle, or in a helix, or if it tends to spin around some axis. Such motion can also be called solenoidal.
Vortical movement is characterized by non-zero curl:
where v is the velocity vector field of the fluid.
The curl of the velocity (at a specified point of the vector field) yields a vector which points in the direction around which the fluid is rotating.
- Ting, L., "Viscous vortical flows" (Lecture notes in physics). Springer-Verlag 1991. ISBN 3540537139