Vorticity

Pseudovector field describing the local rotation of a continuum near some point

In continuum mechanics, vorticity is a pseudovector (or axial vector) field that describes the local spinning motion of a continuum near some point (the tendency of something to rotate), as would be seen by an observer located at that point and traveling along with the flow. It is an important quantity in fluid dynamics and provides a convenient framework for understanding a variety of complex flow phenomena, such as the generation of lift on wings. Mathematically, the vorticity ω {\displaystyle {\boldsymbol {\omega }}} is the curl of the flow velocity v {\displaystyle \mathbf {v} } : ω ≡ ∇ × v , {\displaystyle {\boldsymbol {\omega }}\equiv \nabla \times \mathbf {v} \,,} where ∇ {\displaystyle \nabla } is the nabla operator.

From Wikipedia, under CC BY-SA. More on occurri.