Vorticity facts for kids
The average vorticity in a small region of fluid flow is equal to the circulation around the boundary of the small region, divided by the area A of the small region.
Notionally, the vorticity at a point in a fluid is the limit as the area of the small region of fluid approaches zero at the point:
Mathematically, the vorticity at a point is a vector and is defined as the curl of the velocity:
In the field of flow of a fluid, vorticity is zero almost everywhere. It is only in special places, such as the boundary layer or the core of a vortex, that the vorticity is not zero.
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Vorticity Facts for Kids. Kiddle Encyclopedia.