Consider a velocity field $\vec{v}$ and a closed contour $C$ in the fluid. The integral of the tangential velocity to the closed contour defines the circulation $\Gamma$ along the closed contour. In other words,


\begin{displaymath}\Gamma = \int_{C}u_{i}dx_{i} \notag
\end{displaymath}  



Timothy S Choe
2003-03-15