Vorticity facts for kids

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Vorticity is a mathematical concept used in fluid dynamics. It can be related to the amount of "circulation" or "rotation" (or more strictly, the local angular rate of rotation) in a fluid.

The average vorticity in a small region of fluid flow is equal to the circulation \Gamma around the boundary of the small region, divided by the area A of the small region.

\omega_{av} = \frac {\Gamma}{A}

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:

 \omega = \frac {d \Gamma}{dA}

Mathematically, the vorticity at a point is a vector and is defined as the curl of the velocity:


\vec \omega = \vec \nabla \times \vec v .

In the field of flow of a fluid, vorticity \omega 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.